I just recently added a bunch of mods to my 350 TPI motor. These include: Dart Pro 1 alum. heads, Holley stealth ram, BBK 58mm TB, Holley fuel rail w/ afpr, 1.6 rr, decent cam, long tube headers, and a custom dual 3'' exhaust. This is my problem...after starting the car, it didn't seem to have much thrttle response and back fired badly. I cranked the fuel pressure down and bought a custom Ed Wright chip. Once I put the chip in, the car ran a lot better, but still didn't have as much power as it should and was still back firing. I pulled the fuel pressure down even more. Now it is at 30 to 35, which i know is too low, but there is still back firing. the timing is set between 8 and 10. I was thinking that the timing still might be too retarded and the spark is firing before it can burn all of the fuel. I've talked to some people and they were confused on how to accurately set the timing on my car because of the timing disconnect. I've also heard of guys who run these cars with the timing disconnect permanently disconnected. I'm unsure of what to do. If anyone has some info that can help, please let me know.

 

If you are running an aftermarket chip i would start by setting your timing all the way back to 0. Even with a stock chip that would be the best way to start. Your problem sounds to me like timing. Sounds like some pretty decent mods to you engine. Let us know how that thing runs when you get it going right

 

Sounds like timing to me. Set it to TDC and pull the cap to verify.

 

that's what I figured. would timing that is too far advanced cause back firing though? It's not extremely loud, but it is definitely noticable. It only occurs when I let off of the gas and let the RPM's come down. The guy from fastchips said that I should have to timing set at around 6. Also, what do you think the fuel pressure should be at. I was thinking around 45 psi.

 

I'm running 50 psi with my 24lb SVO injectors and it is working well. 44-50 PSI is the recommended pressure and yes initial timing should be at 6deg BTDC. Set your fuel PSI and check the timing, eliminate the easy things first. If that doesnt do it then you'll need to datalog and get into PROM tuning...