http://www.bug-bits.freeserve.co.uk/bugbits/tech.htm
--- --- --- --- --Welcome to BugBits' technical pages---
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These pages have been put together as an aid to
anyone who is considering building, or having built, a type 1 VW engine for use
on the roads.
The
contents of this document have been put together using 12 years of my
experience on Beetle engines along with books I have read and people I have
spoken to. I raced a Beetle in Guernsey as a hill climb car, it went through
different stages of development as did my knowledge, and it is this learning by
trial and error I wish to help you to avoid. Since then I have built engines,
both standard and performance, for other people.
I
have written a How To page that will explain each of the following section in
detail for those who have never had the opportunity to strip a type 1 engine. I
would suggest you visit that site now, print off a copy of the text and return
to do the same with this one.
Go to the How To <http://www.bug-bits.freeserve.co.uk/bugbits/howto.htm>
site now.
Contents:
Overview
What do you want
Crankcases
Crankshafts and flywheels
Con-rods
Cylinder & piston sets
Cylinder heads
Camshafts and the valve train
The oil system
Ignition
Carburettors
Exhausts
Cooling
Clutches
Running for the first time
Useful data
Overview
So
you want a not out of the box engine for your Beetle, what should you do
about it. There are many, many parts available for your engine, just take a
look inside any VW mag and you will see ads for parts you have no idea what
they are, but sound impressive. The most important part to building your own
engine is not to jump straight in, read, ask and observe where ever you can. My
let down has been living in Guernsey (a small island off the north French coast
of only 30 square miles), when I started racing in the 80's there was almost
no-one I could ask locally who had any idea that a Beetle could produce more
than just a whistling sound, let alone 200BHP, so I had to learn by my own
experience and by long phone calls to Autocavan (sadly now closed down) who
helped without really knowing my full requirements, as nor did I. How could I
know what I wanted until I had experienced it, and without a car how could I
experience it? I wasn't going to enter a 1600cc Super Beetle with standard road
tyres up against 2 litre Ford twin cams boasting huge amounts of power, my
vanity was to great for that.
I am hoping to try and pass on some of my experiences and save you
experimenting as I did. Throughout this document I will try to give you
calculations and comparisons to make it a little easier to make the right
choice. You will still have to make the final choice as I cannot tell you what
to buy, just what ball park to look in.
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What do you want
One
of the hardest parts of building an engine is deciding what you really want,
are you intending to take granny to church on Sunday but be able to keep up
with your mates each evening, or are you after something a little hotter, such
as 100 - 150BHP. If you intend to go beyond the 150BHP mark then this document
is not really for you, only so much can be covered and all out engines,
especially when used on the road, require so many areas to be considered
together that one could fill a book with the possibilities as have people like
Keith Seume with his very informative book 'Aircooled VW Engine Interchange
Manual', which is a 90's version of 'How To Hotrod Your VW Engine'.
Firstly, how much money are you prepared to spend? Now if you double it that
will give you an idea of what it will probably cost. I built a 110BHP engine
for a lad who came to me and said 'I have £1000 to spend, I want.....', and
proceeded to list £3000 of parts alone. When he finished I calmed him down and
explained what things cost. He finally spent £1800, and went away happy.
What sort of power range did you intend to have, 50-75BHP, 75- 100BHP,
100-150BHP? To give some idea of the expected cost, I use the formula BHP X 20,
this gives an amount that turns out to be closer than just pricing up the crank
and carbs.
One
thing you should be aware of, VW made their parts much too strong for what they
were intended, meaning you can retain a large number of parts from your
donor/existing engine.
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Crankcases
There
are many crankcases available, your original case, a new original case, a
clearanced case and race cases, they are all good for what they were built for.
If you intend to keep your original case and want anything over 75BHP you
should only do this if it is a twin port, that is one whose serial number
begins with two alpha characters from AB to AS. They should also have the part
number AS21 or AS41 (this is on the side under the pushrod tubes). Apparently
the AS21, produced after the AS41, has a greater aluminium to magnesium ratio
than the AS41 and therefore handles heat better, although I have never had any
trouble with an AB 1300 case (AS41) up to 180BHP, but I have never used one
long term on the road. Gene Berg has done much work looking into the
differences and advocates the use of AS21 rather than AS41, but I have not
found any noticeable difference.
Old or new? A lot of people feel the need to align bore a case just out of
habit, but I feel this is not really necessary. If you journals are in need of
machining, then yes, machine them, otherwise leave well alone. Take the case to
a machine shop and ask them. Also get them to check the flywheel thrust face,
this will probably not be obvious until you go to set the endfloat and find it
is several millimeters instead of just fraction of one. A new case is the best
way to go, but on a budget this is not always easy. You can buy reconditioned
cases, but personally I'd say no, don't.
Case studs were also changed from about 1975 for 8mm rather than 10mm. The
reason for this is that the 10mm studs stretch once heated more than the 8mm,
once again I've never experienced any trouble with the larger studs. One
advantage to the 8mm studs is that they already have case saver inserts fitted.
It is possible to obtain case savers, these are stud sleeves, which requires
the case being tapped to 12mm or 14mm where the old studs went, then inserting
the case savers, then the 8mm or 10mm studs go into them. Be warned, if you plan
to open the case up for 94mm cylinders you will experience trouble with the
inserts encroaching in the holes, and remember a steel insert will not bore
anything like as easily as the mag/alloy case, in fact it will probably destroy
the cutting tool.
The next case up is a clearanced case, these have been machined for 90.5/92mm
cylinders and the insides have been opened up to accept an 84mm crankshaft.
These cases are very good value for money when you consider the cost of a new
universal case and then the machining costs. These cases often have the oil
gallery bored to allow the insertion of an external oil filter, which is useful
and will save a few quid getting it done later (by the way, these are my
favourite choice of case).
Race cases come from the top names, Autocraft, Bugpack, Pauter, Rimco and Scat,
but they aren't cheap. Use one only if you feel you really have to, or you're a
chap I know who won't buy what will do the job, he has to have the most
expensive. They are, however, very strong, sometimes heavier than a standard
case, but really not necessary for a road going 150bhp engine. Put the money
into something that will make your car go faster, you'll feel better doing
that.
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Crankshafts
and flywheels
If
you plan on using your engine at over 5500 rpm, which is quite likely and the
best way to give you more speed and power, you can forget using your stock
crank. There are, like most other parts, loads of different crankshafts on the
market, the bottom of the range is a welded counterweight 69mm crank. The
counterweights are what allow you to exceed 5500 rpm. All cranks I will mention
from this point will have counterweight on them, either welded or forged from
new.
In case the words "counterweights" are just words to you, here's what
they do. The big end, the bit the con rod bolts to, is offset and so will pull
the crank in an uneven circle, in fact it will put pressure on the bearings.
Imagine a fairground ferris wheel with only a quarter of the people on board
and all together, once the speed increases the strain on the frame holding the
wheel up would be immense, so the speed would need to be kept down. If you now
fully loaded the wheel, the speed could be increased, as despite the extra
weight, it was distributed evenly. The same effect happens with the crankshaft,
so by fitting a counterweight, the extra people, the crank can rotate faster. A
faster rotating crank, a faster moving car.
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After
the welded counterweights comes forged cranks, these come in many different
sizes from 69mm up. There are two crankshafts I would recommend, firstly a
69mm, either welded or forged, and a 78mm forged. These two will give you
reliable horsepower from a 1585cc up to a 2007cc from a standard case.
Crankshafts over 69mm are referred to as 'strokers'.
The advantage of using a 69mm crank is that it can rotate faster than a stroker
(a smaller circle and therefore less distance to travel to complete the
circle). Remember an engine is an air pump, the faster and easier you can get
the air in and out, the faster the engine will go. So with that in mind, you
can see how a short stroke, although giving a smaller capacity and
theoretically a lower power output can run faster and give a higher rpm. For
street use this isn't always a great advantage as it requires the revs to be
quite high to get full benefit, but if you intend taking your animal to the
strip it could work well. Of course this then requires a lot more head work and
getting the exact camshaft for your needs.
All 'aftermarket' (that I'm aware of) cranks come drilled for 8 dowel pins,
these are the bits that keep the flywheel turning with the crank. The more pins
the more chance of the flywheel staying attached to the crank. The nut that
holds these two together needs, as standard, 250 lbs/ft (35mkg) which is quite
an amount of pressure. To give you some idea of what that means, if you hang 18
inches (45cms) down a bar with a socket on the end you would need to weigh
165lbs/75kgs (12 stone) to get it to torque. For a high powered engine I would
recommend about 400- 500 lbs/ft (55-70mkg), this means if you do weigh 165 lbs
you will now need to be between 2.5 and 3 feet (75-90cms) down the bar. All
that weight on a 36mm headed bolt, wow.
The journals (the bits the bearings go on) are available in many different
sizes to fit different con-rods, so you need the matching size con-rods (see
that section), but why cause more expense than is really necessary?
There are also flanged crankshafts, these have a larger flywheel end which
allows for better mating with the flywheel, but does need a special bearing set
and a matching flywheel. More expense.
Whilst on the subject of flywheel mating, there are wedge-mated crank and
flywheel sets available. These have been machined with a taper on both the
crank end and the matching flywheel face, this does work well, but remember,
you might be the one who will have to separate them one day. They work just
like steering rod ball joints, have you ever tried to get one of those off?
But, once again, if you intend to stay below 200BHP you will never need one of
these.
There are heavy duty nuts and larger washers available, they are usually made
of chrome-moly steel. They aren't generally needed as the standard nuts will
take at least 400lbs/ft (55mkg) and who needs a larger washer (they are meant
to keep the dowels in place), where are the dowel pins expected to go? Having
said all that, they aren't expensive.
Your flywheel, apart from requiring the extra 4 dowel holes should be machined
to weigh between 10 and 13 lbs (4.5-6 kgs), the weight must be removed from the
outer most edge (not the teeth) and most machine shops will be able to carry
out this operation for you. You could always buy a ready cut flywheel, but of
course you will have to pay for a flywheel that you already have and then
you'll have one spare when you've finished.
Once you have your flywheel and crank ready, fit the #3 bearing and the two
drive gears, get your clutch pressure plate and take them to a balancer, it is
well worth it as it allows for a smoother running engine along with the fact it
will should help your engine last longer.
Whilst I'm on the subject of longevity, it should be noted that if you increase
your power output you can expect parts to wear out a little more quickly, and
so doing everything you can to make the engine run smoother will slow this
degradation. I will point out anything to help this as we go.
One last point, there are shims in between the crankshaft and the flywheel,
these set the crankshaft endfloat. The recommended gap is 0.07-0.13mm
(0.003-0.005in), open that up to about 0.25mm (0.010in) if your engine is going
to be over 120BHP. This will allow the extra heat to be dissipated better from
the crank and crankcase without binding (NB the case and crank expand and
contract at different speeds).
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Once
again, there are many rods available, your standard rods (use type 311, this
will be cast into the bottom of the big end) should be good as they are for
most engines up to 100 BHP and with a 69mm stroke crank. Once you go to a
longer crank you will either require these rods to be machined or to buy a set
of previously cleared rods, the advantage of buying a set of rods is that they
will have been balanced end for end and as a set, which will help your engine's
longevity.
Like crankshafts, con-rods are available with different journals, and like the
crankshafts you have no need to change from the stock VW 55mm diameter.
Rod length is also an area to look into as this can move the power band like a
cam, higher or lower in the rev range. The length of the rod and the length of
the crankshaft stroke give the rod ratio. Rod length (mm) divided by the
crank stroke (mm) = Rod Ratio. The lower the ratio the lower the power
band, the higher the ratio the higher up the range the power band will move. As
a comparison the stock 1600cc set-up is 137/69 = 1.98, now if you wish to hill
climb you will require a lower ratio (I had a ratio of 1.76) and if you wish to
drag race a high one.
Chevy 327 rods are 145mm long, are strong and cheap (in the US), but will
require some machining as the big end is only 51 mm instead of the 55mm of the
VW, this does save on changing the crank just to match the rods. These used
with a stock length crank will give a high revving engine with a high power
band, giving a rod ratio of 2.10, ideal for a small bore drag engine. The
Porsche 912 rod is a little shorter than the VW, but when it comes down to it
the VW is stronger, not a bad length and it fits. The is the key to
keeping the price down, get things that fit each other.
This is the theory of rod ratio.
A long rod will give a slower piston speed, and therefore a longer life for the
rings and cylinder walls, but this also causes the cylinders to fill up slowly
when the piston moves down during the inlet stroke. Of course, once the rpm
builds this is overcome, hence the higher power band. A shorter rod will, of
course, fill the cylinder much faster and therefore give more power at lower
engine speeds, but be limited to a lower rev range.
There are many aftermarket rods available, but like crankcases I can see no
reason to change to a set of rods costing more than I sell a complete recon
1600cc engine for.
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Cylinder
and piston sets
There
are only a few choices here, you can go for an 88mm or a 90.5mm, in either a
stock or long stroke design. DO NOT EVER USE A SLIP-IN SET as the
cylinder wall are too thin to withstand road use for any length of time. For
the same reason I, along with many others, do not recommend the use of 92mm
cylinder sets. These have the same outside diameter as the 90.5mm sets, but
obviously have a larger inside diameter, thereby giving a thinner wall. As Dick
Nuss would say "Boo 92s". I had a set of 92s which, after only 2 race
meetings, had four shiny lines up and down the cylinder and four beautifully
untouched lines. This was caused by the cylinder becoming squared to the four
head studs and the rings then binding on the walls. Don't let this happen to
you as it costs much more and takes longer to strip down a road going
engine.
Always use a forged piston if you can and use Teflon Buttons. This comes back
to one of my first comments that something sounding good, but you don't know
what they are. Teflon Buttons replace the clips that hold in the wrist pins
(the bit that hold the piston to the con-rod) and won't come loose like a clip
can. They are small mushroom shaped buttons that slide against the cylinder
wall and being Teflon don't wear out, supposedly.
One other part to be aware of is total seal piston rings, these have no breaks
in them and therefore give better compression. I have never used them and so
can give no comment on their ability, longevity and cost.
Here is the calculation for CC, Bore X Bore X Stroke X 0.0031416.
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Cylinder heads
You
can buy some lovely heads from the shops, but know now that they all need
finishing off. No head can be built for your requirements and be a standard
'off the shelf' number. All of these heads will improve your engine as they
are, but you should always consider a little head work at a recognised VW porting
shop.
If you plan to stay under 100BHP then you can happily use your standard VW twin
port heads without any work, less a good clean up. Don't bother with single
port heads, change to a pair of twin ports.
You
can buy 040, 041, 042 and 044 heads, these are all based on the standard VW
head, but still require work to perform well, especially the 041. The 040 has
40mm X 35.5mm valves, the 041 is similar but has 39 X 32 (not much better than
standard, as a recommendation, don't use them), the 042 is a development of the
041, but with bigger valves, 40mm X 35.5mm. The 044 is the best of these heads
and has more metal in the important areas near the valve seats and plug hole
and therefore requires a long reach spark plug. The extra metal helps prevent
cracking, a common problem on all these heads, including your standard heads.
Of these heads I would recommend the 044 greatly over the other 04 heads and
would seriously shun the 041.
My personal favourites for road use is the Eliminator which has plenty of metal
in all the right places and with only a little port polishing they run very
well, although they do need long reach spark plugs. Beyond these are those from
all the top names, these come from Bugpack, Gene Berg, Pauter and Scat, but
remember like any 'off the shelf' head, it will still require some work to make
it perform at its best, so the more money you spend on a pair of heads there is
still money you will need to spend.
Have a look through the catalogues and speak to the vendors, sum up the best value
for money, but don't buy heads that are too big for what you want. Only buy an
inlet valve size you can fill.
I won't go into heads any further as your requirements are something only you
know, so go and speak to a head shop, let them know what you want and see what
they say. If they know what they are doing they will recommend a head and then
be able to machine it to your spec.
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Camshafts and the valve train
Cams,
like heads, are a big area, you can really mess up an engine with the wrong
cam, even more so than with heads. A 1679 with Weber 34ICTs and standard heads
will not run with an Engle FK98 cam.
Cams have two main measurements, the lift, in either millimeters or inches, and
the duration in degrees of the crank. The duration is the time the valve is
opened for, the longer this duration the more fuel gets into the engine and the
bigger the bang when it ignites. Well, that's the theory, in actual fact the
longer the valve is open for the faster the engine needs to be running for this
to happen, so at idle the engine will not run all that well. For street use you
should not consider anything with a duration of greater than 290 degrees. The
most popular cam I have ever seen used on the street is the Engle W110, it has
286 degrees and 0.431" (10.95mm) valve lift. Engle also make the W100
which is often better used on an engine under 1700cc or heavy weight cars (I
use on in my 1776cc crewcab). The duration of this cam is only 276 degrees
which brings the power band down where a smaller capacity engine needs it.
Remember this: The longer the duration the higher the power band, and
subsequently the lack of power in the lower rev range.
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Cam
lift is usually measured in inches ('cos most manufacturers of VW cams are
American, despite being for a German car, don't ask) and either is at the valve
or the cam, so make sure you know which before deciding on one. There are
different rocker ratios as well, the standard rockers multiply the lift by 1.1,
whereas others have ratios of 1.4:1 and 1.5:1, this of course means the cam
lift is multiplied by 1.4 or 1.5 to give full valve lift (less the rocker/valve
clearance, usually 0.004"/0.1mm for inlet and 0.006"/0.15mm for
exhaust, keep this to 0.006"/0.15mm for both on a <100bhp engine). If
you intend using higher ratio rockers, check the cam card closely and check if
you can/should run a ratio rocker with it. The more lift you have the more fuel
goes in and the bigger the bang when it ignites, so the higher the lift the
more fuel (well, it almost works like that). Most manufacturers have their
popular street cams, I've mentioned Engle's, Bugpack have their 4062-10, which
gives a little less lift and a little less duration, Scat have the C35, Gene
Berg has his GB297, slight differences, but all much the same. Any of these
cams will work well on the road throughout the rev range, plus give increased
performance over the standard cam. They all have around 284-286 degrees and
about 0.415 - 0.451". If you want a little more lift without the extra
duration, my personal road choice is the Engle VZ25, but these do work better
with modified heads.
If
you insist in going over the 290 degree barrier, then it's your own fault when it's
a bit sluggish in town. Valve lift is not quite as bad, but please use 1.1:1
rockers as there are very few road cams that are designed to use a 1.4:1 or
1.5:1 that work any better than an equivalent one designed to run on 1.1:1
rockers. Still try to keep your total valve lift to below 0.500" as this
is the limit of a standard head. Forget the 1.25:1 rockers, they really don't
give enough extra for the price you pay.
There
are adjustable cam gears available, don't buy one. You cannot set up the cam
better that it was manufactured. If the cam doesn't match the cam card it came
with it is either a faulty cam or a faulty cam gear, so take it/them back.
There are also straight cut gears, these prevent cam lash caused by the
synchromesh type gear, but as you won't be running dual valve springs, you
won't need these either, plus they are so noisy.
Dual valve springs are available to fit any head, don't buy them, you don't
need them for street use and they slow your engine down. Any extra work you
make your engine do, like open valves with more springs on than they need, will
slow it down. A new set of single springs is a good idea, as this will
keep your valves closed when they should be closed because twenty five year old
springs don't work as well as they did when they were new
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You
can buy chrome-moly pushrods, don't. You can and should consider 'cut to
length' steel pushrods, these will return your rocker arm geometry back to the
way the factory made it, efficient.
Rocker arm geometry: This is getting the valve opening through the full
swing of the rocker arm. To set this up, you will need to get a soft spring the
same size as the valve spring (you can use the inner spring from a dual set)
and fit it. Make an adjustable pushrod, this is done by cutting an old pushrod
in half, removing about 2cms (3/4 inch) from one half, tap and inserting a
length of M6 thread with a nut on it tight into one end and drill out the other
half to 6mm so the thread slips in.
You'll only need the case, cam, one cam follower, crank with one rod on, one
piston without rings, one cylinder and one head (obviously you can have an
almost complete engine, this is just the easiest way to do it). Reduce this
adjustable pushrod to its shortest. Assemble the part mentioned with no pushrod
tubes on. Set the rocker adjusting screw to half way, and extend the pushrod
until you have a valve clearance of 0.006"/0.15mm, turn the engine over
until the valve is half open (you will need a dial indicator for this), at this
point the rocker arm should be level with the head's rocker cover seat (valve
top and pushrod top are level). If not, adjust the pushrod and with rocker
stand shims and valve lash caps (if necessary) until it is level. Recheck and if
OK you can cut your pushrods. I use a lathe for this as I can get the rods to
finish better and be more accurate than using a say or pipe cutter.
When you come to push the ends in after having cut them to length, use a large
hammer and a pair of old cam followers. You will have eight of them floating
around after putting new ones in with your new cam. You must use new cam
followers with a new cam, and not just because the bloke selling you the
cam tell you to. Look after your cam and it will look after you (or was that
something else?).
You can buy hydraulic cam followers and large base followers, don't. There are
light weight followers, I've never used these, but there is no reason you
shouldn't spend your hard earned money on them. Like I said about not using
double valve springs, if you have lighter cam followers the engine will have
less to lift and also return to base a lot faster. This will be of benefit, but
you probably won't notice it.
There are many different valve types available, but use those that come with
your heads, they will probably be stainless steel and all in the price. For
road use you don't need sodium filled titanium valves at several hundred pounds
a set, or anything else too special.
When you install your cam do use the paste they supply with it, in fact splash
it on all over the cam and the follower bases, plus do run the engine as the
instruction says.
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The
oil system
Take
a look at an oil pump, it consists of two gears and a case, not much to it. The
oil is picked up from the centre of the engine (above the oil draining plug)
and enters the pump on the right, leaves on the left and heads for the first
pressure relief valve (the one below and to the left of the pump), if the oil
is hot it is sent to the oil cooler, if not it goes straight to the bearings
via the oil pressure switch. Once here it feeds the camshaft, the cam followers
(which in turn feed the rocker shaft through the pushrods), the crankshaft and
the big end bearings and then the small end bearings. The last part of its
journey is through the second pressure relief valve (this is near the flywheel
end), this keeps the oil pressure to its set value.
You can replace the relief valves and springs with higher pressure versions,
these aren't really worth the effort, as the standard version works well,
although new springs wouldn't hurt. These are often just a longer piston rather
than a longer spring, but sometimes you get both. The spring/valve nearest the
oil pump is the oil cooler bypass and will open when the oil is thick and cold
to prevent the cooler from blowing out. If this valve jams open you will not
get your oil properly cooled, or if the valve remain closed you might blow the
cooler out the next time you run fresh oil on a cold day. The front
spring/valve (nearest the flywheel) is to retain a minimum oil pressure. You
can replace the oil pump with a higher pressure version, these are the same
design except have larger gears in a larger case. I would not ever run a high
pressure oil pump with oil pressure boost springs.
There are oil pump covers available with an outlet pipe, which is to allow an
oil filter to be added. You will have to block the pumps normal outlet by
pushing a bung into the hole in the case (you should tap the case and use a
length of thread with a screw slot in so it can be removed later, if need be),
then drill a hole in the case (you can see the raised part of the case that
goes up and to the left at 45 degrees from the pump, follow that up until it
comes to a lug in the case facing toward you and use that as your return point)
tap this to 1/4 BSP (this is the standard thread type used in oil systems) and
connect your filter. Use externally braided hose, as being so close to the
ground and near so many other parts it will need protecting from damage. Do not
fit your filter where it can be damaged i.e. inside the wheel arch or too near
the ground. DO NOT FIT AN OIL COOLER ON THIS PIPE.
There are also dry sump pumps, these are a two stage pump, the first is the oil
in, this takes oil from a separate tank and pressurizes it into the engine. The
second stage is the oil recovery which is twice the size of the first and sucks
the oil up from the bottom of the engine and returns it to the tank. They are
not all that common on road cars, their main use is when an engine is pushed
from side to side a lot, such as off road. When using an engine in this way the
oil spends a lot of time being pushed into the heads and therefore not near the
oil pickup, so seizure is waiting to happen. These pumps are expensive, they
require an extra tank, a lot more hose and some case machining. Don't bother
with one for the road, you don't need it. I used one for hill climbing as
without one I could not have gone around the bends quite as fast.
There are sump baffles, these work quite well. They are a simple drilled plate
that slips into the case just below the camshaft. The idea is to prevent the
oil easily running into the cylinder heads on cornering and starving the oil pickup.
I have used and am happy with an oil suction kit, this consists of a new sump
plate with an extension to the oil pickup that fits very close to it. The idea
being, it only requires about 4mm of oil to still be able to pick it up, the
standard pickup requires about 10mm.
You could consider a high capacity oil sump, these add about 1.2 pints (0.7
ltrs) of oil to the engine. They come with an extension to fit onto the
standard pickup which collects the oil from the new tank. They have one major
disadvantage, they hang about 3 inches (75mm) below the engine and can cause a
problem with a lowered car. The idea here is that they do not give you any
cooler oil, but it does take longer to heat and you have more supply when
cornering and therefore less chance of seizure.
Mini sumps work like a mixture of the last two sumps, they have an extra mini
sump along with an extension pickup. I still prefer the oil suction kit.
Coolers: There are many different kits available for cooling your oil. If your
engine's oil regularly rises above 120 degrees C you need an external cooler.
These use an adaptor that fits in place of the standard cooler and has two
connecting pipes on, one in and one out, which point towards the flywheel. Some
kits come with fitting instructions that show the cooler fitted to the fan
housing inlet, whoever thought of this should also be strapped to the fan
intake themselves. The air going into the fan housing should be as cold as
possible, warming it up with an oil cooler is rather defeating the object. Fit
your oil cooler somewhere under the car, along side the gearbox or somewhere
where it is out of the way of any passing objects, but close enough to the
fresh air.
Don't run an oil cooler from an oil pump outlet plate (as mention
earlier) as this will send cold oil to the cooler when you start your engine in
the morning which will cause extra stress on the cooler and could blow it out.
That's what the first pressure relief if for, it only sends oil to the cooler
if it's hot. That is why I cannot understand the shops selling uprated rear
(cooler bypass) relief springs and pistons.
---
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Ignition
What
ever you may read, you cannot gain any extra power by changing your
distributor, ignition leads, coil, or spark plugs. You can help the engine to
run smoother and more efficiently, though. Your choice of distributors is
limited to your stock unit, the Bosch 009 or 050 in either a standard
configuration or with a Lumenition Optronic system or other electronic pack.
These electronic units will help your engine run smoothly and with a more
accurate spark, but remember to take a set of point with you on any long trips
just in case they pack up, otherwise you're knackered, they cannot be fixed. If
you change your carbs for a dual system you will need a purely centrifugal
advance distributor. The 009 and 050 are of this type. The difference between
the 009 and the 050 is the advance rate, the 050 gets to full advance faster
rate than the 009, meaning it gets to its full advance at a lower engine speed,
this is not a good idea for a lower powered engine (under 100BHP) as it will
put more of a demand on the engine before it is really ready to give it.
Magnetos, they don't use a coil and are very expensive. They are mostly used by
high revving drag race engines. A coil and 009 is a far, far better and cheaper
option for a road car and one of the most common set ups.
Coils are available in many different types, but they are all basically the
same, a coil of wire in an oil bath. The most common coil seen on the Beetle is
the Bosch Blue, this is a good unit and will give you many happy hours, well,
years. The choice is almost endless, they are made by more names than I care to
mention, and nearly all of them will do what you want, but for the price, and
ease of availability, there is no reason you shouldn't get a new Bosch Blue.
Don't buy used coils, they rarely go wrong, but they aren't that expensive to
take the chance.
You can change to silicon ignition leads in both 7mm and 8mm sizes and in many
colours (the silicon part is the wrapping). The size of the lead isn't
important to a road car, but colour obviously is (only joking). Your original
leads will work well, but a new set can't hurt and they aren't expensive. You
can get deals which include a 009, Bosch Blue coil and a set of silicon leads.
--- --- --- --- --- ---
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Carburettors
Let's
start by reminding you of one of my earlier statements, an engine is an air
pump, the faster and easier you can get the air in and out, the faster the
engine will go. You must remember, though, if you are running a standard
carb and change the air filter for an aftermarket type which will flow better
than the standard VW unit you will need to increase the main jet on the carb.
Note: More air needs more fuel. You can buy adjustable main jets for the Solex
31 PICT-3 or 4 and the 34 PICT-3 as used on the 1300 and 1600 twin ports
respectively. It is a better idea to buy an adjustable main jet, as trying to guess
the jet you need could be expensive before you finally get it right.
Carb choices are getting smaller. The 48IDA was always used with the big
engines, but Weber don't make them any more which is making them difficult to
get hold of. The Americans used to use the Holley Bugspray for the street
engines whilst in Europe we used the Weber 32/36 DFEV. The Bugspray is no
longer available new, whereas the 32/36 DFEV is still going strong. If you can
find a Bugspray it will help a small capacity engine run much better, and an
engine up to 1800cc will like the 32/36 DFEV. The Weber is a progressive twin
choke, this means that the first 32mm barrel does all the main work until you
floor the accelerator and then the 36mm cuts in, which you will notice.
There was, and I think there still maybe, a set of Kadron Solex carbs, these
are two single 40mm Solex carbs on individual manifolds with a crude linkage
(which often loses one of its retaining clips). Having said that, they are good
value for money, as are any other twin single carbs sets.
After that comes the best of the rest, 34ICT, 40IDF and 44IDF. Dellorto also
make an equivalent range, 34FRD, 40DRLA and 45DRLA, the only difference is the
Dells are usually a little more expensive (due to a smaller demand and, in my
opionion, better quality), but if you intend using a blow through turbo system
you can forget the Webers, they can't handle the pressure as well as the Dells.
The 34ICT/34FRD are great for a small engine up to 1800cc, it gives a good
response and is much better on fuel consumption than the 32/36 DFEV. The 34FRD,
Baby Dels, are now no longer made. If you can get some, do, they have two
separate single carbs, one above each head. The 40IDF/DRLA and 44IDF/45DRLA are
twin chokes, which can be used as either single centre mounted or as two side
mounted carbs. The single centre mounting doesn't work well 'out of the box',
but if you can get it jetted correctly it should run well, although
icing is more common with this set up. The best way to run these carbs is as a
twin set up with one either side of the engine. They usually come as a complete
set with manifolds, air filters, linkage and fuel line. They run well on any
engine from 1600cc up, although I would use the 40IDF/DRLA for 1600-1800cc and
the 44IDF/45DRLA from 1800-2000cc.
In my opionion the Dellorto has a far superior linkage system that the Weber,
it uses a hexagonal rather than a round bar, which means the arms don't need
bolting up so damn tight, but have a look at them both and see what you think. ---
--- --- --- --- --- --- --- --- --- --- --- ---
One
point to note, you are likely to have problems using your standard fuel pump
with these dual twin carb set ups. They work well until you reach about 4,500
rpm then can start to struggle. Electric pumps are available from many outlets
and some are designed to replace the existing pump and sit on an adapter next
to the distributor, but most pumps should be run from as near the tank as
possible, as they are designed to push not pull the fuel. There is a nice
recess on the opposite side to the master cylinder along side the front of the
floor pan framehead.
You can use 48IDAs on the road, but you will get better mileage and easier town
running from a set of 40 or 44/45s.
If you plan to run a set of 40s on an 1800, do ask the shop for a set designed
for this engine. The set-up the 40s come with is designed for a 1600cc engine,
using 28mm choke and 115 main jets, where an 1800cc engine will require 32mm
chokes and 128 mains. Use these calculations for your carbs:
Determine carb size: (Square root of (cylinder cc X maximum rpm)) divided by
40 (I would suggest a maximum rpm of 6,500 to 7,000)
Determine choke size: (Carb size X 40) divided by 50
Determine main jet size: Choke size X 4 ---
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Exhausts
OK,
let's go back to what I keep saying, an engine is an air pump, the faster and
easier you can get the air in and out, the faster the engine will go, so an
exhaust with as little restriction as possible is the key to this. A twin quiet
pack will allow the gases out easier than a single, because each silencer only
has to handle half as much exhaust as a single, QED.
You
must be aware of how an extractor exhaust works, as there are many on offer
that are not extractors. To make an exhaust work to help the engine you will
require the four pipes to meet together at the same time, that is the four of
them must be the same length. Due to the extra length required to get from
cylinders 1 and 3 (nearest the front of the car) you need to make number 2 and
4 longer. Look at most performance exhausts and you will see a great winding of
metal, this is to make up the extra length required for the back cylinders.
These four pipes must then merge into a collector together, this creates a
small vacuum in the collector whenever one pulse passes. To put it another way,
when number 1 cylinder exhaust passes through the collector it produces a
vacuum in the other three pipes, as number 4 is next it will be pulled down the
pipe, so helping the piston. The smoother and straighter the pipes are the
better this system works, unfortunately this pushes the collector so far out
the back it is just not practical for a road car. In America I'm sure they can
get away with it, but in Europe we have smaller roads and in Guernsey we have
them even smaller, put it this way, Guernsey has a very high case of broker
door mirrors, on both sides.
To continue the process of helping the gases escape, you can use a
"Stinger" which tapers out for about 18 inches (45cms) and aids this
vacuum effect. Of course, using a stinger on the roads is asking for trouble,
not only are they loud, but they stick out the back so damn far.
You may want to exchange your heat exchangers for "J" pipes, these
are simply a replacement, they do not really aid the exhaust much, but do make
the engine lighter. You will have to make some new brackets for the lower
tinware if you use these.
Don't expect the following exhausts to help the engine in any way, other than
keeping it quiet: Bugpack Universal Exhaust/ JSC Economy Header & Muffler
and GT Exhaust Systems, any dual exhaust (used on buggies/Bajas), Monza
Performance Exhaust, Zoom Tubes/Zoomie (these are very 1970s). Use your
discretion, if it doesn't have a merged collector, it isn't going to help. ---
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Cooling
When
an engine produces more power, it subsequently produces more heat. This means
that cooling is more important now than before. I always fit a new thermostat
to a performance engine, as the cost far out weighs the trouble caused if it
doesn't work. Another favourite of mine is the Cylinder Cool Tin, these are a
copy of the Type 3 under cylinder deflector. They cause the air coming down
from the fan housing to wrap around the lower part of the cylinder far better
than those tiny little plates you have already. Never run an engine
without a thermostat and the associated flaps. I've heard people say things
like, "the daily temperature here is over 100*F", ok, but the
operating temperature of your engine is about 80*C.
You should also use a cylinder head temperature gauge and connect it to
cylinder #3 (as this is always the hottest). The senders for these gauges fit
under the spark plug like a washer, but be careful as they are easy to break. I
have, in the past, connected them to a cylinder head bolt, the upper one second
in from the left on the left hand head, but this does mean drilling the tinware
and more importantly, they are there to stay once the tinware has been fitted.
If you have fitted an external oil cooler you can change your fan housing for
one other than a "dog-house" type (that's the standard type used
after 1971). You must remove the control flaps from within your old fan housing
and transfer them to the new aftermarket one you have bought. The reason for
this is that those flaps allow the engine to reach its correct operating
temperature quite quickly and thereby reduce cylinder wear to a minimum. Be
aware that many of the aftermarket fan housings don't fit too well and do not
have provision for the control flaps, if this is the case, don't buy it. You
really can't do much better than the standard post 1971 fan housing, but
remember if you are going to remove the oil cooler you will need to patch the
back of the housing to keep the air in.
Power pulley are smaller pulley wheels which turn the fan slower and therefore
require less power from the engine, that means the engine will not receive all
the air it needs. It is worth noting that if you intend running your car in and
around town, the power pulley is not for you, but if you plan on running your
engine at high RPM for any length of time i.e. drag racing, you should consider
one as the standard fan doesn't work very well over 6,000RPM (engine speed) and
by reducing its speed it will extend the usable range of the fan. Please
remember, if you use a power pulley in town, you are asking for trouble. There
are also dry sump pump pulleys available, these are even smaller and have been
designed to run with this huge pump. As I have already recommended you don't
use a dry sump pump, you don't need to ask me about these pulleys.
My final point on cooling is this, Volkswagen spend a lot of time and money
working out the best way to cool their engine, so what makes you think a badly
fitting aluminium 36hp replica is going to work any better. ---
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Clutches
Not
too much to say about clutches, just don't use a feramic centre plate for use
on the roads (the feramic pads get stickier the hotter they get, so you cannot
slip them, therefore no good in town) or a pressure plate heavier than 1700lbs,
unless you have a hydraulic clutch system and Arnold Schwarzenegger's left
thigh. Other than that, the choice is yours. There is a centre plate called a
ProGrip, I have just fitted one to a 2 litre I have just built, it feels like a
standard plate, but appears to stick very well considering it have a standard
pressure plate. --- --- --- --- --- --- --- --- --- --- --- --- ---
Running for the first time
All
right, so you've built your dream engine. Don't destroy it before you have used
it. If you have replaced most parts of the engine, and of course, you used an
air line to blow out all the oil galleries to make sure they were open, there
will be no oil in your engine. You can, before you fit the oil cooler, using a
small funnel, pour oil into the hole nearest the pulley wheel end. It will take
quite some time to pass down the line, but if you turn the engine over
backwards by hand this will help pull the oil down. Put about 1 pint/half a
litre down into the engine, then fill it up normally (through that silly
little, offset pipe). Use a good oil, and once you have filled it up and fully
assembled the engine, connect it all up, all except the positive supply to the
coil. The idea here is that you don't want the engine to fire up, just yet.
Turn the engine over with your foot hard down on the accelerator pedal and
until a short while after the oil light goes out (about the count of 5). Now the
oil has passed through the engine you can connect the coil. This time pump the
accelerator twice and leave it alone (until the engine fires), turn on the
ignition and fire the animal up, but do remember what it said on the
instructions that came with the cam.
Right,
now go and show those Ford owners what a Bug can do.
Useful data
Calculations and useful numbers:
Calculate CC: Bore X Bore X Stroke X 0.0031416
Calculate cylinder CC: (Bore X Bore X Stroke X 0.0031416) divided by 4
Deck height CC: (Bore X Bore X Deck height in mm X 0.0031416) divided by 4
Head CC: using a measuring jug (one in c.c.s and in single units) fill it with
100 c.c.s of a liquid (I use ATF 'cos it's red, but you can use anything that
is easy to see) put the head in a vice with the bottom of the valves facing
upwards (you will need both valves and a spark plug in), make sure it is level
and pour in your liquid until it is level with the surface where the cylinder
mates with the head, once there you know how much fluid it took to fill it up.
Compression ratio: (Cylinder CC + Deck height CC + Head CC) divided by (Deck
height CC + Head CC)
Calculate carb size: (Square root of (Cylinder CC X Max RPM)) divided by 40
Calculate Choke size: (Carb size X 40) divided by 50
Calculate Main Jet size: Choke size X 4
Oil temperature: Don't go over 120 degrees C too much
Other data:
To set up a 009 or 050 distributor when using a degreed pulley
wheel, make a mark on the 32 degrees before TDC with a felt pen or liquid
paper, then run the engine using a strobe light attached, slowly raising the
revs, then when the engine is at full advance (you will know when that is as
the mark you made stops moving) turn the distributor to move the mark until it
lines up with the case centre.
To balance a set of dual carbs is not all that difficult, if you
have a carb synchroniser this can be used to measure rather than listening for
evenness. Either way, firstly disconnect the linkage to both of the carbs, then
screw in both idle adjustment screws in about two turns. If you are going to
use a synchroniser, remove the air filters. Now start the engine, it should run
relatively high, now by adjusting only one idle screw up and then down until
the engine sounds sweet and smooth or measures the same on both sides. Turn off
the engine. Reconnect the linkage to both carbs and loosen the adjustments on
one side. Now adjust the linkage on that side until both throttle arms rest on
their stops. Open the throttle from the cable link (centre of the cross-bar)
noting which carb opens first, adjust the linkage to raise or lower that
throttle rest and continue until both carbs open together, then tighten the
linkage lock nuts and re- fit the air filters. Re-start the engine and unwind
the idle screws evenly until you have a nice running engine.
To set up the idle mixture, wind all four screws in gently until they stop,
then wind them out about two turns (as long as it is the same on all four
carbs). Restart the engine, once it has warmed up it should be running
smoothly.