hey all. i am rebuilding my t3 motor down here in tas. nothing spectacular. slightly bigger barrels and a shaved head if i can.
what i was wondering is, how far can i get the head shaved if at all and also if i get the 87mm piston/barrel set, do they go on the stock block? and can i fit a better crank in the block and/or would that be worth it?
also i am taking off the cooling fan at the front. i hate it. so what i was thinking was using twin squirrel fans i think they're called, on top of the barrels/heads, with a . does anyone know of another method of cooling under these conditions? and one more thing.:P i was going to use the stock carbi's and get them re-jetted. is this possible? or a new carb set be better? what to use?

thanks, jonno

A shaved head will higher Your compression....
not a good idea with VW engines....
means extra Heat.....

I've sent You some info pages to your hotmail address.

Lee

Read the gene berg website

Jonno

Yes you can shave (or more correctly - fly cut) where the barrels sits in the head.
As Lee said this will increase compression ratio. To compensate you need to open up the head chamber
This is all dependent on what deck height you have - the gap at TDC from the top of the piston to the top of the cylinder

87s are slip ins. No maching required.

For what you are doing a stock crank is fine

Cooling - leave it alone!
I know a few people experimenting with different fans, but they are very experienced. The stock fan moves a truck load of air.
You WILL cook your motor if you try doing something different

Stock carbs can be rejetted - but i doubt you need to

Here is another good site to read up on

http://www.aircooled.net/gnrlsite/resource/articles.htm 

and here is Gene Berg's site

http://www.geneberg.com/index.php 

>Yes you can shave (or more correctly - fly cut) where the barrels sits in the head.<

For cyls above the 87mm it can be done on either a lathe or milling machine. Actually the correct term is bored and faced! A flycutter is actually a single point tool used in a milling machine for surface milling in place of a multi tip cutter. A flycutter is also a single point form tool for special shapes. If a flycutter was used to do the facing with such a broad surface a fair ammount of chatter would result in a poor seating surface for the cylinders. Sorry to point this bit of engineering out but some motor mechanics do screw up machining terms!

If you have a mate with a minimum 6 1/2" centre lathe and a large enough face plate to hold the VW heads they are quite easy to machine. A milling machine is that other nice piece of luxury but tooling is that bit more expensive as you need a boring and facing head to do a good job.

DH



[ Edited on 15/6/2006 by 1500S ]

Mmmmmm! Can you post a photo of this setup? As a cut of some 15 mm wide is required to re-face the cylinder seat/combustion chamber area. Quite some machine to do the job without chatter so I would be very interested in the setup as would other professional machinists in the group!

DH

Flycutting, by whatever method, is sometimes done to true up the mating surfaces on the heads. The increase in compression can be compensated for by using shims to return original deck height. It is not necessary unless your heads are warped or otherwise damaged, in which case you would be advised to replace them.

What is wrong with the cooling fan? Unless you are an expert, DO NOT MESS WITH THE COOLING SYSTEM or you can kiss you rebuilt engine goodbye.

There is another thread on this theme. If you want a bit more oomf, 1:1.4 rockers, weber carbs, extractors. All these things can be added without taking the engine apart. Maybe consider installing a mild cam while the case is open.

I'm no expert on machining, but I have only ever heard it referred to as "fly cutting"

You are right there PurpleT3. The term is used in general for many things. We use a balanced flycutter (weighted to prevent out of balance) to machine normal heads such as Fords etc. On our beloved VW heads we are re-seating the cylinder holes in the head if they require it (and generally they do). There were aluminium shims available to bring the engine back to standard comp if too much is taken off. When we open the heads out to accept 1916 pots etc, we are boring and facing the recesses. That can be done with a suitable flycutter but it does require a machine with a solid spindle to prevent chatter. It is better with an odd number of teeth on the cutter which requires the tips to be ground exact on a Tool and Cutter Grinder. So that depth the recesses are equal it can be an advantage to take a light facing cut over the bottom of the head to give a full face rather than the 6 little lumps. That way it is easy to measure seat depth with a depth micrometer. If not, we have to generally rely on the zero from a scale or DRO. As for tooling, a facing and boring head for tha mill is the prefered option but will set you back somewhere between $1300 and $2000! You need to machine a few heads to make it pay.

Too much info for the casual engine builder! Sometimes a centre lathe is the better option as a simple boring bar does both boring to accept larger pots as well as facing to the same depth. The rocker cover face of the head can be used as a datum in this case but still better to skim bottom face and depth mic from there.

Phew!! But this is a technical section of the forum!

DH



[ Edited on 16/6/2006 by 1500S ]

Until you learn a bit more, maybe you would be better buying a second-hand performance engine. Saves a lot of dramas, expense and heartache!

thanks for all the info guys. i will look into this cooling further. i have seen heaps of vw motors without the cooling on there, but they all had the full flow oil systems, which i was going to do, but maybe they're doing something else. also whats a gearbox reco worth? and can u get different ratio sets for it for different tyre sizes etc. and does anyone know of a good place to get an airconditiong kit? the ones the hot rodders use with the chromed pumps?

cheers again, jonno