Re: Spider cylinder head height?

[AlfaNeely@domain.elided]

In a message dated 11/23/2002 10:36:23 AM Central Standard Time, 
trentkc@domain.elided writes:


> 
> At 04:30 AM 11/21/02 +0000, you wrote:
> 
> >        It is always good to measure valve to piston clearance.  Put 
> modeling
> >clay on the piston tops, assemble the engine, time the cams, gently turn 
> it
> >over a couple of turns, take the head back off and measure the clearances.
> >
> >Ciao,
> >Russ Neely
> 
> I've been following this cylinder head height thread with some interest, 
> being in the middle of a rebuild, and after having had the good ol' boy 
> machinist I'm trying to train to take too much off when all I needed was a 
> "cleanup" (now 111.6mmm).
> 
> Doesn't the method suggested above ruin the head gasket, e.g., after 
> assembling (and I assume torquing) the head gasket, it will have been 
> compressed and be unusable for the final rebuild for a running engine?  I 
> thought head gaskets can only be used (torqued) once?  The alternative I've 
> 
> heard is to run a piece of thick lead soder through the spark plug hole 
> positioning it such that it is between the piston crown and the valve, 
> rotating the engine, then pull out the soder and measure its thickness 
> where it was squeezed between the crown and valve.  What are acceptable 
> clearances?  Which valve is more likely to have clearance problems - 
> exhaust or intake?  Assume 1750 w/stock valves, 11mm intake, 10 mm exhaust 
> cams,  tight valve lash ~.014-.016..
> 
> THanks.  Good digest topic!   ///kct, Powell, TN  (perpetually behind on 
> threads)
> 
> 

       What makes a head gasket used is heat.  If you just assemble the 
engine without running it, the head gasket can be used again.  Or at least, I 
have reused them.  Your results may vary.
       If you are worried, do the test assembly with an old, but pretty good 
shape head gasket.  Or buy two new head gaskets.  A head gasket is cheaper 
than bent valves.
       The advantage of modeling clay over solder is it leaves a profile of 
the valves on the piston tops.  That gives you a better idea where to cut the 
piston.
       If you are pretty sure, you will have adequate clearance, but want to 
make sure, then use the solder.  If you are pushing the clearances and 
anticipate additional machine work, use modeling clay.

       The intake valve is more likely to have clearance problems as it is 
larger.  Acceptable clearance?  Got me, man.  What can you live with?  How 
much are the parts going to grow with heat and movement?  I figure 0.025 
inches should be enough, but again, your results may vary.

       As far as being perpetually behind on reading Alfa Digest, I just skip 
a few digests periodically to keep up.  The ones I missed were probably about 
the wrong wheel drive 164, mixed with tips on how a high power stereo will 
make the Alfa faster, interspersed with SUV and Japanese car haters / lover's 
comments.  And of course, the ubiquitous question of when Alfa is coming back 
to the US.
       Guess which threads, I scroll past...

Ciao,
Russ Neely
Oklahoma City
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