I just did a compression test on my 425 that has been bored 40 over 6000 miles ago. The manual says it should be 180. I got an average of 213 (210-216) I'm concerned about detonation since it's a daily driver. A vacuum test showed 18 instead of 16 at the manifold. The vacuum advance is pulling 21 degrees at idle ( I bought the wrong one) It runs fine ( I reduced timing by 3 degrees to make up for advance error.) My question is what setup would be best for efficiency (read daily driver) And what is my compression ratio now? was stock 10.25:1 right? Now it's higher! What kind of gas do you use for that? thanks shane
Shane , The boost in compression pressure results when the over bore is squeezed into the same size combustion chamber. not a problem. The dist. needs to be set up in a dist. machine to plot the adv. curve. Lots of hp here for alittle money, and it doesnt go away. nail heads arent as prone to detonation because of the pent roof combustion chamber. You could use the old mechanics formula 6 deg. initial advance for a 6 and 8 dg. for a v8. Doc
distributor machine? Where does a person get the thing curved? and what should the curve look like? thanks for the info so far. I feel better already. shane
