Crazy Backfiring

[roysgreenstang]

the rockers and distrubutor have been checked by an experienced mechanic and everything was perfect, firing order is as per the book says in the haynes manual under HO. Im sure its 13726548. Thats just from memory though, right now for 2 more weeks im in afghanistan so i cant check again, but its been checked so many times im sure its correct anyways. I have heard that gear drives can play havoc on a computerized car, but i cant figure out how, considering my mustang, i dont believe, has a knock sensor. I was told to replace them with the original type timing chain. Any insight on that would be helpful. Also the axhaust ports on the heads that i have got are at least twice as big as the exhaust ports on the heads that came off, would that in anyway produce the problems i am having, please keep in mind that the car at idle and no load seems to be running fine. Does the backpressure affect it that much. I changed the distributor to make sure that it wasnt the problem, again it wasnt. What problems exactly will i encounter from these heads being too big for the motor as you put it. Noone i have talked to said that it would cause anything other then a little less torque at low rpm. Is this going to cause me more headaches then the heads are worth. I was considering just taking another stock 5.0 and piece by piece changing everything that i changed from stock until the problem arises again, but thats alot of work and really im sure that it is something that can be fixed easy enough, i just cant seem to pin point it. The timing gear drive and the heads are the only things that i am thinking could be the problem, hoping for some feed back on this, i miss my car, and would like to drive it soon after i get home, thanks for the help guys.