I have checked the distributor (it's in right)
Rockers are just barely down from zero lash.
Getting spark.

It will bust right off then die within about 3 secs. Seems to be backfiring through the carb.

I made sure the valve timing was right by bumping it over. The motor is at TDC of the exhaust stroke. The exhaust valve just closed and the intake is starting to open (I watched it). Distributor is about to fire cylinder #6.

I guess it might be something with the carb. I will pull the bowls today. Sounds like a timing problem to me. But i don't know where.

I am running out of options. I need something for target practice and the car is very close by


[This message has been edited by jcb999 (edited October 04, 2001).]

 

this may sound simple but check to make sure you have all of the ignition wires in the proper firing order. also, make sure your timing is somewhere close to o degrees advanced. if it's there then you can rule out timing as the problem. backfiring is usually a timing problem.

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'86 IROC 5-speed
305 LG4
edelbrock performer rpm intake
edelbrock 600 cfm carb
msd pro billet hei distributer
'95 3.23 rearend
hotchkis rear suspension
PST front polygraphite suspension
"speed kills. buy a f@&d, live forever."

 

yep.. i had marked the distributor location before.. should be about 10-13 degrees advanced. and I checked the firing order

But, it's got to be something like that i have overlooked.

 

what did you do to your engine? It would probably help to know what you did in order to figure out what you may have forgoten, done wrong, etc.

 

Have you checked your timing chain? You realize that if it jumps a tooth, the distributor will maintain the "same ratio" as it does to the valves. It's the timing of the valves to the pistons that changes.

 

just been gone through. Used previous carb, and ignition. Did not remove coil or ignition box. Only pulled distributor connector and removed distributor when the previous motor was taken out.

New chain. Cam degreed on a 105 intake center line with the dots lined up.

I would think that any incorrect valve timing would show up in the overlap period. And it was clear when the exhaust began to stop movement and the intake started. Thats where it is now (tdc of exhaust stroke)


[This message has been edited by jcb999 (edited October 04, 2001).]

 

My vote goes to the carb/fuel pump

Intake backfires are caused by retarded timing and/or lean mixture, you said timing is good, so I say it's the mixture... enough fuel collects to keep the car running for a few seconds, then it dies...

 

thanks for the input.. I am running out of things so fuel delivery is next.

It has a electric pump and the demon has clear float level site glasses on the side.. but I can't tell what happens after it gets in the bowls.

I am not ready to shoot it yet.. but soon.

 

do u have and electric choke? if not just pump the gas a couple times and then fire it up. mine usually goes after the fourth time of starting. it will start then die, so start it again by pumppin the gas and then floor the gas when it starts to warm it up.

 

well crap.. carb looked perfect inside. Good flow between main jets and boosters. Good accellerator pump shot. I had almost convinced myself that I had the distributor 1 notch too advanced b/c the rotor is pointing right at the cap for cyl 6. But, it should be there, with #1 on tdc of exhaust stoke, cyl #6 is at tdc of compression and firing. In other words, cyls 1 and 6 have crank pins 90 degrees apart. Which accounts for the 90 degree V angle. I was thinking that cyl 6 actually is not firing when number 1 is at tdc of exhaust but 90 degrees later.

 

Man, i would STILL double check where the wires are plugged into the distributor- if its getting fuel, and its getting spark, yet its not runnin, then the spark isnt occuring at the correct time....

That said i tried to find a diagram of the numbering on the distributor, maybe your one off all the way around, yet still in the correct order! this is what happened to my dads blazer when he did plugs and wires on it... he had the correct order, yet they were ALL off by one....

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86 Firebird, LG4, t-tops, 2.73 open rear, SLP 3 inch cat back exhaust, catco cat, 1 inch carb spacer, Fiberglass cowl induction hood, Formula wheels, vette servo.

Current Plans: Waiting on: rear end parts- upgrading to 373's, 28 spline axels, slp zexel torsion posi, and a disk brake setup. Also have lowering springs, front struts, and hopefully a new mild 350.


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