[Evan Purple240]

I have a 72z with a crane hi6 ign. My problem is that when the timing is set to what seems to be the best place(runs strong for awhile), if i get on the gas the motor starts dropping power(misfiring) and backfires out the tail pipe. After it starts doing this it does it at all rpms in all the gears. Usually i can gimp the car to a parking lot, where i can adjust the timing to get the car home. When i do this i lose most of my power. I have tried two distributers that i have (mallory & stock) they both seem to be afflicted.

Please help, im lost and my motor only has 200 miles on it.

Thanks-Evan

 

[jeff]

> I have a 72z with a crane hi6 ign. My
> problem is that when the timing is set to
> what seems to be the best place(runs strong
> for awhile), if i get on the gas the motor
> starts dropping power(misfiring) and
> backfires out the tail pipe. After it starts
> doing this it does it at all rpms in all the
> gears. Usually i can gimp the car to a
> parking lot, where i can adjust the timing
> to get the car home. When i do this i lose
> most of my power. I have tried two
> distributers that i have (mallory &
> stock) they both seem to be afflicted.

> Please help, im lost and my motor only has
> 200 miles on it.

> Thanks-Evan

Has it done this since you put in the new engine combo? A couple of things to check are the coil, can be tested with an ohmmeter, and the connections to the coil, + to ignition hot and - toyour trigger source(points, magnetic pickup or opto couple)
also if you have condensers in the system (for point type or for noise suppression) they can give exactly the same symptoms you have described, they heat up during use and start to cause intermittent missfiring if they are bad, usually will be fine for a few feet to miles and then start acting up. good luck!