Quote Originally Posted by DennyW
52º..??? ... total should not be over 36º
Do you mean "TOTAL" total? Or just "initial and mech" total?

I dont think that sounds unreasonable (52 deg). I think what he is alluding to is cruise/no load timing such as the highway where he might be running @ 2900rpm or so, initial + mechanical +vac adv puts you right in that ballpark wouldnt it?

Case in point, and tell me where this goes wrong....

'69 350cid, 255hp (extracted from a MOTOR's Manual)

Initial timing is 4deg BTDC
Mech is 32deg @4400rpm (crank degrees, advance starts around 1000)
Vacuum advance is 24deg at 13" vacuum

So at 4400rpm cruise, it would be 4+32+24 = 60 degrees assuming 13" of vacuum

Backing down to 3000rpm...you have 4+18+24 = 46 degrees total timing.

Okay, not quite 52 degrees , but more than 36 degrees. Point being, if the car is tuned to run lean and clean, should it not be able to handle the extra timing at cruise?