>Now that I've gotten the head off of my '72 B, an interesting
>question comes up. I have an 18V, low-compression engine
>(18V585ZL1203), with dished pistons (probably stock).
>I also have a 1965 cylinder head, which, I believe, has larger
>combustion chambers than the later heads, since the earlier
>pistons had less of a dish to them. With the dished pistons
>and larger combustion chamber, am I running some godawful
>low compression ratio?
Yes ... with the older head 18V pistons you are well below
the stock 8:1 CR for the 18V engine ... you have increased the
capacity of the combustion chamber by approximately 4.5 cc
... so say 7.5:1 ... 8^0
B Series Engines ... the heads fitted to 1500 and 1600 engines
have 1.5" intake and 1.281" exhaust valves and a 38.7 cc
combustion chamber ... the 1622 and 1798 (18G thru 18GK)
engines have 1.565" intake and 1.345" exhaust valves and a 43 cc
combustion chamber ... the 1798 18V engines from '71-74 have
1.625" intake and 1.345" exhaust valves and a 38.5 cc combustion
chamber.
Shaving the older 43cc head by *approximately* .045 will
decrease the chamber capacity to 38.5 ... this will get you back
up to an 8:1 CR ... 9:1 CR pistons are available for the 18V
engine (they were fitted to Home Market engines) so ya might
consider a set.
There is an alternative to shaving the head and fitting the stock
9:1 CR pistons ... Venolia will make a nice set of forged pistons
to any spec (bore/dish) ya want for $280... ;^)
I don't have any reference material with me so the previous info
is from memory ... I'm an OF so ya better double check it ... ;^)
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