View Full Version : backfire help.

09-05-2007, 09:53 PM
buddy of mine got a mustang with a nitrous kit on it.

single nozzle wet

big edelbrock solenoids

~45 psi fuel pressure

its got an unlabled gold/brass nozzle?

we believe we have the lines hooked up correctly, if someone could describe how they go it would be appreciated.

anyways, he has these jets in it

NX 62
??? 38

we went out and he hit it at like 2500rpms , auto btw, and we saw a flash under the cowl hood and heard a loud bang, he has no filter on his intake piping, 5.0 88 fox.

next we hit it again at 3200rpm for like a second and it pulled fine and dandy, then we hit it at 3500+ rpm and after about 2 seconds it popped VERY loud again and flames went EVERYWHERE through the back of the cowl.

whats going on? i have verified that both solenoids are indeed firing.

09-06-2007, 08:25 AM
anything i can like.. check for ? i mean, we have the nozzle facing the correct direction in the intake..

can anyone verify the jets for being a 150 shot, 62 nx n20, edelbrock 38 fuel.... does that sound right?

09-06-2007, 08:57 AM
wow, umm, stop. Is he running colder plugs or pulling the timming any? Because that sounds like as soon as the air/fuel is mixing it is fireing, may be caused by too much heat, or maybe his spark advance is wrong, or maybe the cam timming is wrong. What all is done to the vehicle?

09-06-2007, 10:52 AM
You need to make sure that you're pulling enough timing out.

09-06-2007, 07:08 PM
he tarded his 84 svo straight up for this car, the previous owner had it setup for a 250 shot. its a 5.0, x303 cam, twisted wedge heads (no idea other than that), automatic, et streets (more on that later), the thing has a msd ignition, and a digital retard box, i found the directions on how to use the retard box last night, but anyways, as it was set when i looked at it is pulling 8*. which, for a 250 shot, is about right imho. he set the jets down to a 150 shot, but we dunno because of the different jets as stated above.

im gonna go see what plugs he has in a bit.

09-06-2007, 07:10 PM
oh yea, the et streets thing, i know your not supposed to lug an engine and spray it. its auto so i figured it would be ok (seems to have a ~3k stall). i wondered if the fact that it doesnt spin at all, it was in effect: lugging the engine.

but like stated, we tried it at 3500rpm too...