Holley 750 backfire.
Well got it all in today except the timimg issue and it does the same thing :(. I'm ruling out the carb as the problem. Can it possibly be a problem with the ecu box being from a small block vehicle? Plug gap maybe? There tapped at 35. And there autolite 85 plugs. Even through a edelbrock dual plane on it and same thing, I hope it's not something inside the motor? It will rev up in park good but it alway happens when I punch the throttle car spits throughout the carb. Good it be a fuel issue? I am running 89 octane. And the engine has the trw six pack pistons. I'm going crazy!
If its farting back through the carb the "most" commen issue is timing, low timing, not advanced enough, or not advancing quik enough, but a lean transition will do the same thing, I'm guessing timing at this point, especially if its acting up about the same with the changes, You yourself feel at this point its not the carb, your most likely right. How does it act'd if you stab it from a 20 mph role? If it does fine once it gets going i doubt its a fuel problem, If you don't have one already, i'd mount a fuel gauge "on the cowl" so you can see it at all times, also make sure there are NO vacuum leaks. Like i said earlier, that cam needs alot of initial timing & a fast curve, & the converter at 3000 & the timing all in at the same RPM doesn't help matters, What gears are in it?
The ECU & plug gap are fine, I'm just not a big fan of the MP stuff anymore, unless its the Chrome box & the mallory style MP dist. thats fully adj., it has the gold plate with light springs & 2 hex screws with a slider plate to adj. the amount of advance you want, plus you can lock it out, Anymore before i plan a build, I make sure i have the whole fuel system up to par, A readable fuel gauge while in the car, & a VG ignition system & simple adjustability, along with good cooling. I never have aggravating issues anymore.