PT3BOOMER

OK maybe I was being stupid, but i was at a red light, revving my engine, shifted into drive(after it idled down)and on green i floored it.......i roasted the tires then POW!!!! engine died. I had smoke coming through the aircleaner and after it stopped, i kept turning it over but it didnt start, then after about five minutes of trying it started!!!!! i changed the plugs and wires, but when i start it, idles fine, then i start driving and i starts backfiring again then shuts off!!! i noticed only under a load it does it but not all the time....its sporadic, it happened to me yesterday on the interstate. I drained the battery trying to start it, and i waited on my buddy to jump me which took him about 10 minutes to get there but as soon he jumped me off it started!!!! i dont know what this could be.....please help!!!!

camaronewbie

Sounds like an ignition issue to me. You need to verify that you got the firing order correct when replacing the wires. Need to make sure all the plug wires are securely on all the plugs and cap points. If still does it, then test each plug wire with a volt/ohm meter set on ohms - there should be very little if any resistance on any of the plug wires. Even if they are new, they could be bad - I've gotten plenty of bad plug wires new out of the box.

PT3BOOMER

Everything is good.....is there a possibility I jumped time? It idles fine and I can rev it in park but if I'm goin down the road and I floor it the car surges forward and after two seconds it backfires and dies.....then I have to wait about 10mins before I start it

camaronewbie

Anything is possible I guess. I'd check my timimg with a light before I tore into the chain cover.

naf

iTrader: (7)

Take a close look at your distributor, check especially for play in the shaft.

Weak spark from bad ignition components is more likely to act up under load when the higher cylinder pressures require more spark energy to ignite the charge. Failing to re-start 'could' also be ignition. You can also try a spark tester on each of the plugs.

Good idle and revving in park doesn't point to 'out of time'.

PT3BOOMER

Could it be that the carb is giving it too much fuel? It's a 1968 qjet 750cfm on a 305...

naf

iTrader: (7)

It's unlikely that the carb failed in that way if it was running fine before. Of course with ignition problems you'll see wet, black plugs when you pull them which may lead you to think it's over fueled but it's just that the spark isn't burning the fuel that's there.

Your symptoms are consistent with a dist going out, especially the failure to restart when hot.

If you're running a mechanical qjet have you already swapped to a vac advance dist in place of the original computer controlled dist?

The qjet will only provide the CFM that the motor needs as long as the AV and pull off are set correctly. If it's not bogging, it's set correctly.

PT3BOOMER

i think it might be the dizzy but no sure......like i said it idles fine in park revving and everything but it backfires as soon as you stomp on it......when driving when the engine is warm

LoneWolf88

I saw something on this site about backfiring through the carb being a symptom of a bad cam, can someone chime in the confirm this

PT3BOOMER

Well it does it intermittently....not all the time so I'm leaning towards a carb issue....just bought a Edelbrock 750cfm so hopefully that may be it, but I have to get an adapter plate and other shyte to put it on...hope my hood closes.....

naf

iTrader: (7)

Intermittent? Not sure how that points to the carb?

Good luck with the edelbrock. Still running the stock computer controlled distributor? Or do you care?

PT3BOOMER

I put an Edelbrock 750 1407 on it today and it ran fine but it shut off and wouldn't start again, had fuel odor too but if it did that with 2 different carbs what would cause that? I don't care about the dizzy being comptrolled. I'm thinking about switching dizzy with non comp HEI

naf

iTrader: (7)

Without the original computer controlled carburetor the dizzy is no longer computer controlled. It's now running on a weak, limp home timing advance mode. You need to switch to a mechanical/vacuum advance distributor if you're going to run a mechanical carb-the mechanical qjet OR the edelbrock. You're losing power AND mileage with the stock dist now.

"if it did that with 2 different carbs what would cause that?"...ignition problems?

PT3BOOMER

I've been running a mech carb for a while now so how come it didn't do that when I first did 3months ago....it waited til now to do this?!?!?!

naf

iTrader: (7)

The failure was not related to running your dizzy without the computer connected. Something's probably just worn out.

BUT...for the past three months you've been getting less mileage and performance than you would have gotten had you:

1) kept the ccc-qjet and properly maintained it

OR...

2) swapped in a standard HEI with mech/vac advance when you removed the computer controlled carburetor

PT3BOOMER

Thanks guys!!!! I switched the dizzy for a mech and vroooom!!!! It was great....nice pic up....now if I can only get an aircleaner for the carb.......without cutting a hole my hood...