I have a vortec 355 and i am using a late 70's vacuum advanced GM HEI distributor.

The problem that i am having is that when i put a timing light on it, over 2500 rpm the timing light stops reading every spark, so does this mean that my ignition isn't firing properly? because it seems to rev up without a missing sound.

Just wondering if there is an easy remedy for this , like could i replace the ignition control module with a performance one from MSD, or if i should just go ahead and get a different distributor (accel,MSD,etc...)

 

Car runs well? Lots of power, etc?
I'd guess it's the timing light then.

Try clamping it on different wires, just for fun. Just to make sure you get a steady blink at say 3000RPM.

 

well yes it does have power, but i know it's not the light. it is only a year old and i tried it on my friends mustang and it didn't miss a beat.

another thing that i have also noticed that makes me think that there is something wrong with my distributor is that my car doesnt pull as hard up top as it does down low..... and i have been in other cars and have noticed that they pull harder up high in the rpm's.... i know different engines run different, but i still think there is something wrong with my timing.... could a weak pick up coil cause this???

 

You've got an extremely generic HEI distributor. I don't suppose you know anyone with a 75-85ish chevy V8 vehicle, and you could borrow their distributor ? I'd try that, before I went about fixing anything.

I'd see if I got a steady blink on other wires. If only cyl#1 does that, then it might just be a break in the wire. Sorta an intermittent problem. Or pull the plug, reconnect the plug wire, start up the car, and hold the plugs ground strap against the block. Rev it up and see if you can watch it start to miss.