Fine tuning

[swedefish]

First some figures about my build.
383 cid + .040
Square decked , pistons .022 down in the hole, steel shim gasket
915 heads with bigger valves
KB dished pistons
According to my calculation this would give a 10.2:1 in static CR.
MP purple cam 284/484
Eddie RPM intake
Eddie 750 carb
Eagle rods
4-speed

How much use do I have of the figures about the dwell angle, vacuum advance degrees and mechanical advance from the Plymouth service manual?
Which numbers, if any, can I use when tuning the engine?
Or is it a test and trial that is needed ?

Btw: The vacuum advance numbers says, "Degrees at inches of Mercury", 0 degrees at 4,5" to 8" .
Sorry for my ignorance but what does it mean in reality. Use a vacuum pump and apply a 4,5 " of vacuum and then read what the timinglight says? preferably 0 degrees.
Many thanks in advance.
Lenny

 

[1wild&crazyguy]

????
I believe you mean how do you tell what timing curve is needed right?

As much initial possible that it will still start with and not kick back, then what ever, by trial and error, total timing runs best with like 34-38*.
After those 2 are figured you can play with advance springs till you get the curve=advance rate dialed in.

Example 24*@ idle/initial and 32* total with an 8* advance all in by 2200rpms

 

[swedefish]

Thanks Wild
Yes, you´re right about the timing.
Figure I have to start somewhere with the tuning and that would be to check the vacuum advance degrees and the mechanical advance degrees, as it is now. If that is needed?