how much initial advance for a SBF ?

[zrayr]

Originally Posted by kiwigt

Newb here, resurrecting a (slightly) old thread and seeking your collective assistance. I have a 66 Mustang GT Fastback with a Roush 342R stroker engine.
I am installing a brand new set of Jim Inglese 48 IDA's.

Jim advises I want to start at 8-10 degrees initial timing advance, and deliver a total of 38 degrees at the crankshaft, this would be 4-5 degrees initial lead and 19 total degrees of advance in the distributor.

I'm using an MSD distributor. Can anybody advise on bushing / spring selection based on the above please?

I have a set of Jim's 48 IDA's on a 289 HiPo engine, and am using msd dist. and digital 6 box. I was experiencing an off idle bog that no amount of experimentation with jetting (under Jim;s guidance) was helping much. He was also wanting me to increase the initial timing from the stock 12 degrees. That helped a little, but not significantly. (A HiPo 289 K code engine has initial timing at 12 degrees and 40 degrees at maximum advance). No adjustment of the full advance timing was doing much either. Finally I started experimenting with the advance springs. Bingo. Best performance was obtained by using the lightest advance springs, AND starting with 19 degrees initial advance and going with the 21 degree bushing, ending up at the stock 40 degree full advance.

With the stock 10.0:1 HiPo pistons, I have zero evidence of detonation or pinging. For ease of starting and to reduce the load on the starter I have the msd box set for a 20 degree start retard.


Z.

[kiwigt]

Thanks for your reply zrayr - that is an interesting insight. I will bear that in mind with my settings, and if its ok I may PM you for further information once I get this installed....