Sampson

My 350 has developed a miss at high Rpm. I broke the cardinal rule and changed several things at one time. A few basics. Rebuilt 350 w/Pertronics Electronic ignition. All new ignition components. Plugs, wires, coil' Pertronics module. Timing is 34 degrees all in by 3300 without VA. Initial set to 14 degrees. Miss developed after I upgraded to a performer intake and newly rebuilt Q'jet with a mild,performance tune. I also changed the gap on the RS45 plugs from .032 to .040. Valve springs were matched with the cam and replaced during rebuild. My gut tells me this is an ignition thing but there is no miss except at high rpm 4000-4500. It runs great otherwise. Is .040 too big a gap?

oldcutlass

For a points replacement .040 is probably to big, drop it back to .035, however I doubt that's your miss. Try disconnecting and capping off your vacuum advance line, test for a miss and see if it goes away.

Sampson

[QUOTE= Try disconnecting and capping off your vacuum advance line, test for a miss and see if it goes away.[/QUOTE]

Too much timing with it hooked up????

oldcutlass

Yes, depending on which advance can is in there and with you maxing out your total timing it may push it way past 50 which will cause detonation under light throttle.

Sampson

Well, you may very well have hit the nail on the head Eric. I didn't think of it in my first post but the VA was disconnected before I changed the intake & Carb. But I have not heard any detonation. I did have some detonation under part load with the VC disconnected before.

oldcutlass

Glad you found the problem, your going to have to limit the amount of total advance with vacuum to 50 or under.

KDV

I was running the same setup but developed a detonation. Had to replace my vac with an adjustable vacuum advance.