Ford Repair: sefi, fuel air mixture, ford bronco

Question
Steve,

I have a 73 Ford Bronco, original 302.  3 years ago I installed a sefi, all matched to a 93 manual mustang.  Am not running any emissions, no egr, tab and tad and egr vacu dis-connected, but egr relay plug still in.  all sensors are new.  have a windsor-fox jumper/adapter in the main-engine harness for proper injector firing order,standard 302.  Distributor wired as such.

Problem is at times, say running constant rpm for a while, when I go to accelerate, or run at high rpm, I get a lot of popping in my headers.  took it to a dealer, upped the idle speed, matched spark plugs, new plug wires, check voltages, all seemed fine.  Started gettin popping again.

What it sounds like is spontaneous detonation in the headers.  If so, why is vehicle running rich?  Or why isn't it burning all the fuel/air mixture?  

Also I am running a conical filter, but I recently put  a shield in front of the intake so as not to allow the radiator fan to cause pulsating probs in the intake.

I can remedy the prob by backing off or pumping the accelerator.  Sometimes it happens, other times not, just can't seem to figure it out?

Any ideas/suggestions?


Thanks, Trip

Answer
Trip-

  It sounds like your timing might be of a bit.  You may also be running a tad rich.  My guess is that the exhaust valve is staying open too long allowing either a spark to ignite unburned fuel in your exhaust gases or a small amount of gas is finding it's way to the exhaust system and spontaneously combusting due to the extreme heat.  Either way my guess would be that the timing's off just a little.  Hope this helps.

Steve