The Ford Barn

34fordy · 05-25-2015, 08:14 PM

If air pressure at sea level is aprox. 14.7 lbs. per sq. in and your old
flathead had 6.3 to 1 compression ratio, does this mean that a compression test should yield about 92 to 93 lbs. if all is well in that cylinder? Or have I been breathing too many exhaust fumes?--I realize that valve timing and other factors have an effect also but just trying to see if there is a (norm) that one could use to compare--If a fellow writes in that he has 140 lb.s in each cylinder after hi-comp pistons someone else with a stock engine wonders what is wrong with his 90 lb. readings-- Don

05-25-2015, 08:14 PM	#1
34fordy Senior Member Join Date: Dec 2014 Location: Fort dodge, Iowa Posts: 1,229	Engine compression test If air pressure at sea level is aprox. 14.7 lbs. per sq. in and your old flathead had 6.3 to 1 compression ratio, does this mean that a compression test should yield about 92 to 93 lbs. if all is well in that cylinder? Or have I been breathing too many exhaust fumes?--I realize that valve timing and other factors have an effect also but just trying to see if there is a (norm) that one could use to compare--If a fellow writes in that he has 140 lb.s in each cylinder after hi-comp pistons someone else with a stock engine wonders what is wrong with his 90 lb. readings-- Don Last edited by 34fordy; 05-25-2015 at 08:39 PM. Reason: more info