Aircooled VW South Africa

My opinion - get rid of the copper head gasket. Others swear that you should use it.

Do a mock up and once you have the piston and barrel on, measure the deckheight. Distance between piston crown and top of barrel. Adjust using the spacers under the barrel, adding or subtracting. Cut your own from shimstock if needed.
Once you have all the bits and you put it all together you will see. If not, then read the article again

Just hoping for the best leads to tears

Blitzkrieg wrote:How do I set the deckheight?

My 1700 Type 4 has shims under the barrels, and the original factory head gaskets.

Common advice to type 4 owners is to remove the gasket and lap the barrels into the head with valve grinding compound.

Now, do I simply do that or just reassemble everything as stock, including the head gasket?.

Or should I dispose of the head gaskets, leave the barrel shims and just reassemble and hope for the best - apparently this would increase the comp ratio slightly -BUT what about the deckheight?

Advice from experienced folk would be appreciated...

Perform a trial assembly (without sealants) of the crankcase, crankshaft, connecting rods, cylinder barrels, pistons and associated components, omitting the barrel shims. Then check your deck-height clearance, for each of the pistons at TDC, using either a straight-edge & feeler gauges or a dial-gauge micrometer. Once you have knowledge of these measurements, one can then consider the next step.

Nigel A. Skeet wrote:

Blitzkrieg wrote:How do I set the deckheight?

My 1700 Type 4 has shims under the barrels, and the original factory head gaskets.

Common advice to type 4 owners is to remove the gasket and lap the barrels into the head with valve grinding compound.

Now, do I simply do that or just reassemble everything as stock, including the head gasket?.

Or should I dispose of the head gaskets, leave the barrel shims and just reassemble and hope for the best - apparently this would increase the comp ratio slightly -BUT what about the deckheight?

Advice from experienced folk would be appreciated...

Perform a trial assembly (without sealants) of the crankcase, crankshaft, connecting rods, cylinder barrels, pistons and associated components, omitting the barrel shims. Then check your deck-height clearance, for each of the pistons at TDC, using either a straight-edge & feeler gauges or a dial-gauge micrometer. Once you have knowledge of these measurements, one can then consider the next step.

Will attempt this and if I can't come right, will take it to someone who can do it. Good to learn new things.

If I screw it up, I can only blame myself

tony how would one increase you cr? Like to 10:1 and how do one calculate it?

louisvr45 wrote:tony how would one increase you cr? Like to 10:1 and how do one calculate it?

start a new topic and I'll answer it there

A comment from Aircooled.net's John:
"I had one engine that the pistons just kissed the heads,
.028" Deck (0.711mm)
84mm stroke
8500 RPM"
That was a type 1 application where he was testing the limits of deck height.

In another example, a prominent guy on STF ran 0.65mm deck height in a type 4 engine- 914 for well over 200 000 kilos without issues. The bulletproof strong type 4 bottom end probably helped here.

Comment by those who ran tight decks was that no space is necessary to provide for carbon build up. The squish will blow this area clean, and this was confirmed when heads were removed for inspection. Problem may be when small parts like loose accelerator jets fall down the intake manifold.

Piston speed around tdc is not as fast as we would think. Between 3 degs btdc and 3 degs atdc it is quite slow.

For long term reliability i would be careful and not go below 1mm. But, more than 1.2mm is not optimum and wasting fuel. However, this is assuming that deck on all 4 cylinders were measured, and not a crude "volume rebuilt" application.

Some people do not understand the efficiency of squish. Some rebuilders will even cut a large step in the chamber when not asked to do so, or shim the cylinder for much larger deck height than even standard specs. The thinking there probably that ultra low compression engines have a better chance to survive their guarantee period.

Here is a site that has most info you need,

very helpful for spec's.

http://www.headflowmasters.com/helpful- ... iUIVH87n3A

Herman

retrovan wrote:Here is a site that has most info you need,

very helpful for spec's.

http://www.headflowmasters.com/helpful- ... iUIVH87n3A

Herman

Awesome, thanks Herman