missing, slight backfire?

[wanew]

Missing, slight backfire?

I tuned my 71 350/270 yesterday, well, actually, I detuned it evidently. I changed the points, rotor, condensor and set the dwell to 30. My timing is 8 degrees B. I put in new plugs. The car was just purchased. I did not change the coil or plug wires. It has a slight continuous backfire or misfire. Any ideas what to check or replace next?

 

[Bender]

I dont know but my has a slight non continuous backfire too

 

[brusso]

Well, if it wasn't backfiring before the "tune-up" , I'd start with rechecking the firing order. 1-8-4-3-6-5-7-2

 

[rgtrough]

Hey Wanew, put on new plug wires, if nothing else make sure spark is getting to each plug. With the close proximity of the plugs to the exhaust manifolds the heat does major damage to the plug boots. I have fouled plugs putting them in the cylinders by getting dirt on the tips and not wiping them off. If nothing else changed then it is nothing too weird. peace Bud

 

[714Speed]

Yeah, I just went through the same deal with my 71 350\270. You should definitely change the wires, too. NH

 

[Scooter76]

As said above recheck your firing order. #5 & #7 are easy to get crossed & since they are next to eachother in the firing order the motor will run with a mild miss to it. I have done this several times in the past.