I was always under the impression that 230 1bbl engines were around 9 to 1 compression but looking through my 1967 guide I find that ZF and ZG 230 1bbl engines
are listed as having a 7.9 to 1 compression.
How was this accomplished as all the info I have says that 230 1bbl heads all had the same volume - 59.6 cc-
From Woodland's guide:
66&67 230 1bbl - 59.6 cc valve length 4.90, 230 4bbl - 47.7 cc valve length 4.99
68&9 250 1bbl - 65.0 cc valve length 4.80 , 250 4bbl 55.0 cc valve length 4.90
If combustion chambers were consistent, how was the compression reduced - different pistons (seems unlikely), thicker head gasket (most likely)?
Am particularly interested because the engine I'm rebuilding is coming in at a lower compression than expected - a 230 .030 over with a 1966 1bbl head is coming in at around 8 to 1
How was this accomplished as all the info I have says that 230 1bbl heads all had the same volume - 59.6 cc-
From Woodland's guide:
66&67 230 1bbl - 59.6 cc valve length 4.90, 230 4bbl - 47.7 cc valve length 4.99
68&9 250 1bbl - 65.0 cc valve length 4.80 , 250 4bbl 55.0 cc valve length 4.90
If combustion chambers were consistent, how was the compression reduced - different pistons (seems unlikely), thicker head gasket (most likely)?
Am particularly interested because the engine I'm rebuilding is coming in at a lower compression than expected - a 230 .030 over with a 1966 1bbl head is coming in at around 8 to 1
