289 popping

[srvblues]

I have a 67 289 Mustang slightly modified, cam headers eldebrock 570 holley electric choke when I try and start it, it pops and wont stay at an idle, it idles for about 30 seconds it fires up fast, but the popping drives me nuts is it a timing issue? Thanks Jeff:SNSign:

 

[2nd Mustang]

Did this just start happening? Is this a new engine? Did this happen after something added or changed?

It really sounds like a firing order problem or extreme timing issue or extreme vacuum leak or........

 

[latamud]

do you have old spark plug wires? Maybe the spark is arching between wires and firing multiple cylinders at the same time off timing. If you have the engine running at night without light you can see it happen, spark jumping across wires. Cool looking but causes popping and jerky driving condition.