I've been having issue's with my car missing during hard exceleration. I've checked the timing and it is right on the money. I readjusted the valves and believe I migh have a cylinder a little too tight.. Would this cause missing?? The back fire isn't coming from the carb it sounds as if it's coming from the exhaust... Any opinions would be appreciated. Thanks

Mike

I forgot to mention that the engine and everything installed on the engine is new, carb., distributer, etc.

If you are using HEI , make sure you have the full 12 volts to the distributor. If the resistor wire is still being used, you will get high speed/ high load msifire.

JWagner, Sounds like what I was getting at the track a week or 2 ago. I just installed a new Undercap HEI from M&H but it seemed like the engine was doing that before the switch.
Any ideas on what the fix is if its not getting the full 12v?

Thanks.... I'll repost my results...

For a quick check, put a jumper from the battery plus terminal directly to your HEI and see if that cures the misfire. If not, then it is internal to the HEI. In general, the misfire could be a bad coil or something that prevents the coil from becoming saturated. This could result from short dwell time caused by a bad module. Of course, check the ignition performance by bringing your timing light into the car during the test drive. This will confirm an ignition-caused misfire.

OK, I admit it, I am losing focus on this topic. First of all, put new good spark plugs in you motor. We have been looking at all kinds of stuff related to producing a poor spark, but have missed out on the quality of the plugs.

Gott'er fixed... Readjusted the valves... Makes a world of difference....It's like she's a total different beast..

Glad you got it fixed.
Back to Hijacking thread...
JWagner, I put in new plugs,wires were changed beginning of winter,checked firing order,cap & rotor look ok. & had the missfire all teh way out to the track, at High vacuum it was worse. My conclusion timing too far advanced, backed it down at the track.Made 1 poor run & went home.
Missfire still occured on way home(after backing timing down). Disconnected vacuum adv on the side of the Hiway. resumed drive home= missfire diminished. Could my vacuum adv be pulling too far? Or maybe the centrifugal adv along with the vac is causing too much.
I'll be pulling the dist and put it on a Distributor machine to determine the true cause