hey my car has been backfiring and im not to sure what is making it backfire. i have it at a mechanic at the moment an he has told me that all he can think of is that its the cam because the engine isnt stock and it has a performance cam in my 302. any suggestions on what could be doing it? it has a new 600 holley on and thats about only thing that i know of that has been modded on it.

You need to tell us more about the motor and its particulars.

ok what i know about it is that i bought it off a guy that he didnt realy do anything to it cause he was gona put the engine in an xy but never did and sold it .... the engine had 650 spread bore carby and found out today that it has a performance cam. the guy that he bought this car off was the one that did modifications and put the new engine in it and since the new engine was in hadnt done much k's cause he sold it to the guy i bought it off an he didnt mod anything and just been sitting in his shed for a while so its a fairly new 302 engine with 650 spread bore holley carby and performance cam with fairly new twin exhaust system. also overal car looked like it mght hav been stripped cuz many parts were missing on it and twin exhaust looked not stock because of bumper bar and other parts were changed.

ye so 302 v8 with 600 carby twin exhaust and performance cam