rebuilt gm 350 stroker starting problem

I have a rebuilt gm 350 stroker ( now a383 ci) it runs perfect except when I start it cold it kicks back into the starter. it cranks over perfect until I hit the ignition switch we set the timing at the least possible advance and still get good performance when I start it hot it starts flawlessly. the ignition system is a 1996 thunderbolt 5 system. I am afraid I am going to break a tooth in the flywheel during cranking.Is it possible that the ignition module is bad ? allowing to much spark advance during a cold start.

 

What degree do you have it set at? If I remember correctly my Chevy 383 stroker was 15 deg BTC

 

we set it at 16 dg and the spark advance is not disabled

 

That may be your problem. When I was checking the timing on my son's 91 pickup, the manual said to disconnect the computer's timing advance wire before I set the timing. I set it to 0 deg then hooked up the computer, which then automatically advances the timing to 12 deg. But it varies - the computer will change the advance depending on the temp of the engine; so you can never absolutely know what the base timing is set to without disconnecting the computer.

 

You need to set base timing to the specified value but for a boat not quite as advanced as in a Car I think in the 10 - 15 deg range after all the motor will not have to lug or near stall. When you disconnect the wire the thunderbolt unit dose not effect the timing as this disables the advance module.You can set the timing then and when you reconnect the wire the computer will remember that position as the base timing position.
Alex