plug gap

bbc blown alcohol 871 blower,msd 7al2+ ngk b9es crank triger, what would be a good safe plug gap?

 

also,does msd make a retard box, to retard off the starting line, need to take out more timing on the starting line then ramp back in.

 

You will need to gap the plugs fairly tight. .019-.021. If you gap them too large you will drop cylinders under a load. Timing as far as I know should be retarded down track not off the starting line. You want the timing to get the car moving under a load.

 

the car is a top dragster,with 28 total timing left the line at 4000 chip bad tire shake 6.90 @197 1.10 60' next pass 3600 chip, 6.62 @ 199.8 1.00 60' no shake but like to more timing for more mph, this was with a 598" bbc 871 @12% over 28* timing no port nozzels @1850lbs

 

Using the exact same setup you have, except a 14-71 @ 50 over, I ran .016 gap with the 7-al box and it worked well. I think you could safely run .020.

 

thanks was running a plug gap at 28 thought that was to much

 

I'm surprised you get away with that much cylinder psi and a 7al

 

I think you have to put a 6-shooter on it or use the 7al-3 instead of the 7al-2. The 3 has retard steps built in to it.

 

we gap our tfx at .009 with msd 10