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well, i'm gonna say right off the bat that I can't live with that.
using my calculator im coming up with at zero deck 8.153.with a normal h.g.so if they are in the hole alot,mayb e 7.5-8.1
Yeah, Im coming up with 8.0:1 or thereabouts now.
I'm getting (depending on the site) anywhere from 7.5 to 8.5 to 1
I wonder if Dan remembers.
okay the 781s i have seen and tested all came up to 117-119cc range 3 sets.the flat tops either have 2 valve reliefs or one.depending how far in the hole,im gonna say 8.1.
Originally Posted by 396_Ways_To_Spit Thats a pretty wide range of cc's for the chambers. You want to get them all as close to each other as possible. Those are just the ranges I have found advertised.heads appear to be unmolested...
Originally Posted by hotbo the 781s have a 118cc combustion chamber,you need to find the piston volume if they have domes and claculate the h.g. with the piston cc and h.g. volume,how far they are in the hole and you will get the correct compression,hope this helps im not trying to get exact, just ballpark. Pistons are flat tops. Motor is about 80 miles away so its tuff to look at.
all the part #s are correct.
the 781s have a 118cc combustion chamber,you need to find the piston volume if they have domes and claculate the h.g. with the piston cc and h.g. volume,how far they are in the hole and you will get the correct compression,hope this helps
here ya go.....
These pistons are not compatible with Gen V or Gen VI engines. Approximate compression ratios: 12.50:1 with 116.9cc, 12.21:1 with 119cc, and 11.58:1 with 124cc head
I think you have the numbers mixed up. I cant seem to find the numbers that you posted.....
Thats a pretty wide range of cc's for the chambers. You want to get them all as close to each other as possible.
Pistons are flat tops, Im thinking with that chamber compression is in the 8.5:1 range...
Can anybody tell me what approximate compression this generates?
Head is a 336781 oval port casting which reportedly measure in the 113-120cc range for the combustion chamber.
Piston is what appears to be a cast TRW L3027F. Piston is for a .030 overbore.