ZERO clearance of the valves of a type four engine?

[Bob Paxton]

My neighbor and friend Sal has a Type 4 engine in his very nice VW thing. That in it self is nothing to get all excited about except that it is a Jake Raby engine! Wow, I said to myself and Sal, I've heard of him (he frequents the talk forum on a regular basis and is a fan of the Type 4 and it's possibilities). Aparently the engine is not running well and he asked if I could take a look and I asked what he has done most recent that would cause this. He has installed a custom exhaust (made in Conn. ) and he has checked all the valves and assures that the valve clearance is set to Zero. After stuffing my eyeballs back in my head, I questioned this process again and Sal has assured me that I heard correctly and that the setting is zero and the push rods turn freely. I am in NO means questioning this proceedure, I would like someone to just verify this as correct (Jake himself can reply) I like it straight from the horses mouth! We all know that one of the first things to check on a Porsche engine that is running poorly is to first check the valves (cold of course). Sal says that I can mention Jake Raby's name and that he should recognize his motor and the owner Sal (we are in the middle Hudson Valley of NY). He is running the "nikkies", dual webers and all the other gadgets that go into a street Type 4 buuilt by Jake. My reason for this listing is an explaination of the ZERO valve clearance so I can continue my search for the "miss" and the performance that resembles running on 3 cylinders. I am familliar with type 4 motors but not these! Give it too me anyway you want! always willing to learn! Thanks Bob Paxton

[Glenn Ring]

It depends on the material the pushrods are made from. Stock pushrods are aluminum and you set them to .006' lash when cold. If it has chromoly pushrods then you set them to a "loose zero", meaning there is no lash but you can still roll the pushrods between two fingers.

The reason is as the engine expands the aluminum does also, but the chromoly does not.

[Steve Proctor]

Hydraulic "lifters" (cam followers) are available for the Type 4 and have zero lash. Remembering 35 years ago from the small block days, I think you even run a little negative lash. Tighten down until the noise goes away and add 1/4 turn or something of that ilk...

[Steve Proctor]

By the way, if you want to validate the efficacy of the zero lash setting you can always run a compression check. I would think that any built up engine, particularly with esoteric elements such as hydraulics would come with tuning instructions. The owner should not have to put a basic tuning question out on the forum....

[Jake Raby]

This is the first time I have heard of Sal's issue. I received a call from him a few weeks back, but the number he gave me was not a working number and he never tried contacting me in any other way.

He could have posted the question directly at my engine owners lounge (see http://forums.aircooledtechnology.com )or emailed me for an immediate response at the address I use especially for Turn Key Engine support engineadmin@aircooledtechnology.com .
I don't have time these days to frequent the forums other than my own.

Sal's engine runs zero lash due to the pushrod and cylinder materials that it uses. He has the Owners manual on the engine that should give him all the information needed to tune the engine. His engine is several years old and while I do my best to support engines forever, its a real challenge when they populate every corner of the Earth..

Sal's engine will tune as any other Type 4 engine. My enhancements have not changed the basic tuning principles and the only tolerance that has changed is the valve lash.

More than likely its a clogged idle jet or intake manifold leak... Other than that we really never have any "gripes".