You guys have been so helpful the last time I had a problem. I'm sure that someone has an answer or some suggestions where to look.

I have a 67 Mustang Fastback 4Speed. I've installed a 351 Windsor with a moderate cam, Edlebrock Performer Series Carb atop a new Edlebrock intake manifold, MSD distributor, and shorty tubular headers. When I got it all put together, it surges whether under power or crusing or idling. It also backfires through the exhaust at times. I've checked everything I could think of for vacuum leaks - replaced the intake manifold gasket, the exhaust gasket and the carb base gasket. Also when I screw the idle adjust screw on the right all the way in, it has no effect. Because I have an MSD distributor, I have blocked all of the vacuum ports except, of course the EGR port.

I've put engines together before so its not like I'm a novice, but this really has me stumped.

Thanks in advance for any ideas you might have,
Bryan

 

I have a 351 cleveland having a very similar problem. Mine runs ok and idles fair but when driving if I rev past about 3,000-3500 rpm it spits sputters and sounds like it is backfiring out of the tail pipes. It does it pretty violently so I don't keep it doing it for long. I was told on other sites that it could be timing, valve springs, or very bad vacuum leak. I have brought it to a shop that has a chassis dyno and I will pay them to figure it out. I will post what they find and maybe I can help you with your issue.


Thanks

Darren

 

Thanks for response. Isn't it frustrating to have a problem that, even though you have done everything you can think of, persists? Hope you find a cure for your car. Looking forward to hearing from you.

65wagonmaster

 

If you know the valve springs are good and the valves are set properly, and the ignition timing is correct, then it's prolly a carb tuning issue. Surging while you drive it is quite often a lean condition. What CFM is the carb and what jets/metering rods are in it? If you're running a smaller carb on out of the box tuning 9/10 times it's too lean

 

I have the same problem with my 93 GT I was wondering if your car only does it when it reaches operation temp or does it do it all the time? Mine, only at Operating Temp
I'm pretty sure 67mustang is heading you in the right direction about being too lean cause I'm thinking the same thing about mine
02 sensors will do that.
EGR will to. Good Luck let me know if you get it.

 

Yeah, on EFI sensors can throw the tuning WAY off when they go bad. As far as carbs, you gotta put it where it needs to be. I put a Holley 570cfm on my 302, and had to go up 3 jet sizes, and radius the inlet on the largest jets I used, though it may still need to go a bit bigger. Because of the wide array of engine combos that you can put together, the carb's out of the box tuning is reasonable close for most applications. But if your's ain't most applications they tune it for, it could be a fair bit off. If you used a smaller carb than what they intended it for it'll prolly be too lean, and if you use a bigger carb, it'll prolly be too rich

 

wat r u running for heads?? i had simular prob and i put gt40 heads on and its sweet