Everything is in line, timing, good spark, vacuums lines checked, it just continues to back fire and I can't seem to figure out what else would be causing this?
Distributor lined up with number one plug, firing order correct, tripled check everything!!!
302 rebuilt, new heads, 4bl holley, electronic distributor.
Replace plugs, distributor cap, new coil.
Thanks

 

Check all you plug wires again one more time.
Could you have accidently got a cam with a 351 fireing order? They fit right in. You would never know it.

 

Hope this helps: When I was younger I rebuilt my first 289. I was so excited. Everything was lined up and I turned the key..Engine spun and fire, then died...I checked everything again and lined up, turn the key and the engine fired and died. After several hours of this I took the front cover off, thought maybe my timing chain and gears wherenot aligned. Nope, I left the crank key off the crankshaft and well you guest it...timing never stayed in place. Once the key was installed and everything realigned the 289 fired up and ran like a champ. Ifyour enginecontinues to backfire and not run you know that you have spark to the plugs. Are you sure that your cam and crank gears are in synch? Are your valves adjusted correctly? Have someone crank the engine as you advance or retardthe distrubutor. Recheck the intial valve adjust.
Jeff
ASE-Engines

 

Yes, I hope I bought the correct cam, I did get a Hipro Cam for a 302, everything was lined up correct, timing chain, I have someone help with all that. We are starting it from under the hood, and yes we have been adjusting the value to see that helps. Still it will start, just back fires alot while running.
We've pulled the distributor out twice and make sure it was lined up correctly, and it seem to be, I was just not sure if there something else that could causing it backfiring.

 

Is it backfiring thru the intake/carb or the exhaust? I agree with RobbieG, check those wires. I know that on certain cam set ups the firing order changes dedpending on the cam. Read your cam install sheet again to be sure. It is easy to forget the little things.. Must use the 302 firing order: 1, 5, 4, 2, 6, 3, 7, 8. No 1 cylinder right side bank. The 351W firing order is: 1, 3, 7, 2, 6, 5, 4, 8
Jeff

 

If it's running and backfireing at an idle, sounds like a tight intake valve. or 2or 3

 

Using the firing order fromt the intake, and also double checked it against myMustangrebuildbook.
We are reveiwing the value again.
Thanks for the help.

 

Yes, but the cam will either be standard 1,5 etc or HO 1,3 etc. The timing has to match the cam you're using. But it sounds like it may be too tight of a valve as well. Recheck the timing and make sure it matches the cam you have(check the cam card for your cam) and if that's right then recheck your valve lash on all your valves

 

Pulling the timing cover to make sure it the correct one, and see if it lined up correctly. Was going to compare it against the my stock one, I bought the cam and chain from the same place, I would have thought would have given me the correct timing chaing, this is only a mid cam, would a stock timing chain still work?

 

Krobillard....did you get your engine running? Let us know what the problem was or if you still have the backfiring issue.
Jeff
ASE Engines