Another way to do this would be to clay the pistons. This is usually done to
check valve-to-piston clearance, but it could also work for the rest of the
chamber area.
Basically you put a thin layer of modeling clay on the top of the piston,
bolt the head on with a head gasket, then turn the engine over a couple of
times. Pull the head and measure the thickness of the clay at various
points. You can then grind away on those areas of the combustion chambers
where the clearance is too close.
The advantage of this approach is that you can get a reading on a large area
of the combustion chamber at once. The disadvantage is that you don't get
the arm development. ;-)
But if you want to use the "no head gasket/contact" approach, using some
machinist's dye (sometimes called "Prussian Blue") will give you a clearer
image than an oil film.
Gordon Glasgow
Renton, WA
> -----Original Message-----
> From: owner-datsun-roadsters@autox.team.net
> [mailto:owner-datsun-roadsters@autox.team.net]On Behalf Of
> Keith0alan@aol.com
> Sent: Saturday, April 08, 2006 6:52 AM
> To: drlsmith@telus.net; datsun-roadsters@autox.team.net
> Subject: Re: Building an engine?
>
>
> Here is what I did on the R16 engine I am currently rebuilding.
> The head had
> been shaved too many times so the pistons hit the head with no
> head gasket
> (the normal test for fit). I cleaned the head and pistons and put
> a thin film
> of oil on the pistons. Laid the head on the engine with no head
> gasket and
> turned the crank till the pistons just touched the head. Pulled
> the head and
> looked to see where the oil transferred. Using the sandpaper
> flap wheel in the
> die grinder I removed a small amount of material from the head where it
> touched. Cleaned things up and put the head back on the engine
> and checked where it
> touched again. After about 50 to 100 times the head perfectly
> matched the
> pistons (and I added 3" to my arms). This restored the squish
> band area to
> where is was supposed to be. When I measured the combustion
> chamber volumes they
> were within 1%, Lucky considering the shaving that had been done on this
> head. If they had not been so close I would have removed
> material from the pocket
> area to even them up. The final compression ratio ended up being just a
> little over the 9-1 stock ratio, about 9.3 as I recall.
>
> A proper squish band engine setup is very efficient. It allows
> higher CR and
> better performance that more exotic things like the original hemi
> head. (the
> current "Hemi" is a registered trademark and has nothing to do with the
> combustion chamber shape. My bet is that it is a squish band engine.)
>
> Enough rambling for now
>
> keith williams
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