I have a 71 302, which I put electronic ignition on. I haven't changed the spark plugs in over 4 years so yesterday I changed the plugs, set them at .035, this morning when I was driving to work the truck started to tremble then backfire I could smell gas also (spark isn't burning the gas) so i just took it back home I haven't looked at it yet but I did check the plugs I took out which was gapped at .050. I know the gap increased as the electrode wore away. I think the timing needs to be adjusted or the plugs are gapped to high and the spark isn't burning the fuel, I just wanted to get some thoughts from the experts here.
thanks in advance.

 

What do you mean by "put electronic ignition on"? A pertronix conversion? or Duraspark? or -?-

Have you checked to see if the distributor is just loose?

 

Duraspark II, I haven't been out to check anything due to me working yesterday; I probably want get to it until Fri or Sat because I'll be working late the rest to f the week. It was running fine until I changed the spark plugs.

 

Sounds like wrong firing order, happens a lot

 

I'll double check that when I start trouble shooting it however, I took one spark plug off at a time to guard against that but I do have the firing order to check against.
Thanks

 

While you are going back to check your firing order, take a flashlight and look down inside the spark plug wire boot at the end that goes on the plugs. You shuold be able to see the central core of the plug wire bent back over and crimped to the metal end. If it looks black and burnt then you have a bad wire.

I think the plug gap for a 302 with the Duraspark is somewhere in the .045 range

Good luck
Bobby

 

I checked the firing order it's correct then I regap the plugs to .047, still the same thing, then I put the splitfire plugs back in still the same then I noticed a sucking noise the plug on the back of the carb base had come off I put it back on and it ran great now I feel real stupid. I guess I'll take it out on the road tomorrow to make sure that was the issue, then change the plugs back to the new ones...

 

I've heard of a lot "stupider" things -- at least you found it and at $0 cost!

 

............LOL...........

Stupid? Don't feel stupid, as Ross saidyou fuond the problem and it cost you absolutely nothing to fix. It happens to all of us (more times than we'd care to admit). We get in a hurry and start rushing around, then when a problem shows up we overthink the issue and completely overlook the little things.

Enjoy the ride
Bobby