Backfire

[JVR]

Hi, I have a CJ7 1984 with a AMC 258 i6 / 4.2l totally rebuild. I installed a new MC 2100 1.08 but in low is making backfire. The timing is setting at 8.

 

[LongHorn]

Hi, I have a CJ7 1984 with a AMC 258 i6 / 4.2l totally rebuild. I installed a new MC 2100 1.08 but in low is making backfire. The timing is setting at 8.

Backfire in a carbureted engine usually is a timing or lean mixture, as the timing is not advanced to much I would think you have a lean condition. Maybe a dirty fuel filter, air filter or maybe a weak fuel pump or a carb kit.

 

[JVR]

Thanks for the help but the fuel filter, carb and fuel pump are new.

 

[dalefan88]

have you tried changing the mixture. i have my motorcraft at 2 turns out on both screws. it dont like any more or any less than that.

 

[LongHorn]

Thanks for the help but the fuel filter, carb and fuel pump are new.

A vacuum leak on the intake manifold can also cause a lean condition there bye backfire.

 

[LongHorn]

A vacuum leak on the intake manifold can also cause a lean condition there bye backfire.

Even the carb to manifold area can have vacuum leaks.

 

[Cheepjeep85]

especially with an adapter plate most are not exactly great quality