Re: Subject: i-head on eta block

["Jeff Roberts" <jroberts@xxxxxxxxxxx>]

An easy way to check piston to valve clearance is to put a layer of
plasticene on the top of the piston. Use new stuff that's plenty flexible so
you don't bend a valve. Then put on the head using the old head gasket and
the old head bolts. Torque it up per the mfr's specs and then CAREFULLY
rotate the engine through two complete revolutions (camshaft turns at half
engine speed). Use a ratchet on the big nut on the crank. If you feel any
resistance during the rotation don't press your luck. Now remove the head
and section the plasticene and measure the thickness with a depth guage. My
recollection is you want at least .070" to ensure the valves stay away from
the pistons at high RPMs but I would check with someone who builds race
motors to be sure of the clearance number.

Also pay attention to the clearance between the piston and the head itself.
If the combustion chambers are different the piston could hit the head
somewhere.

Now you can clean all the plasticene off.

Hope this helps

Jeff

>Date: Wed, 5 May 1999 07:19:02 +0100
>From: Horst Apfelthaler <Horst.Apfelthaler@domain.elided>
>Subject: i-head on eta block
>
>Hello,
>I'm in progress of doing an e to i upgrade on my 11:1 euro eta engine.
>The eat pistons are domed, and according the information I collected the
>i-head steals me 1 bar of compression due to different shaped combustion
>chamber.
>(37cc eta versus 42cc for the i) - which should result in 10:1.
>But:
>I remember the i-pistons have some cutouts for the valves.
>Is it necessary to have them also on the 11:1 eta pistons?
>Can anyone tell me some tricks how to determine in an easy way if
>I have enought valve clearance to the pistons?.
>
>Regards
>
>Horst
>
>see my car at: http://silverstone.fortunecity.com/chicane/541/
>'80 323i project car
>'89 320iC
>'95 A4 Tdi
>

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