Rusty is on life support

[rustybronco]

Okay, I've got an interesting problem I was hoping you guys might have some ideas on. I've got a freshly built 302 with a rochester just purchased from BCBroncos. New fuel tank, fuel lines, new holley pump. New wiring, coil, petronix ignition upgrade. Everything is new except for the basic distributor. I fire it off for the first time 2 nights ago and runs really good. Finally today I start it and let it break in for a while in the shop, drive it to town, runs pretty good overall but starts to cough when you really give it gas. Also won't idle down even with the adjuster screw backed totally off. Stop to get gas and 2 blocks down the street it starts to cough really bad and won't idle at all. Get it home and that's where the frustration begins. I try different coils, put points back in, change plug wires. I discovered that if I significantly advance the timing it will idle (like 40-50 degrees!), but still runs awful. I've got plenty of fuel to the carb, in fact the plugs looked fouled. Great compression. It's almost acting like the timing chain slipped (but I'm almost positive that's not it because it's a fresh motor) What's bugging me is it was running pretty good and then something all of a sudden went wrong. Do you think it's the carb? I have no clue on adjusting quadrajets. Any ideas would be greatly appreciated!

 

[BBowski82]

Is the timing advance working properly?? also, what is your base timing set at? and have you checked your total timing? (this will tell you if your distributors advance is working...sounds just like an ignition advance problem

 

[rustybronco]

You might be on to something there. To get it to run initial timing is probably around 50-60 degrees. I can't tell because it's off the scale. But it should be around 30 right?

 

[BBowski82]

Well chevys are generally around 32* total timing...I would imagine Fords would be close

 

[BBowski82]

Another concern I have is this....Did you replace your feed wire to the coil so that it no longer has a resistor in line?? this is a big thing. You should have 12 V at the positive side of the coil with Electronic ignition and like 7-9 V with points....

 

[rustybronco]

Yeah, I tried it all ways just to be sure. 12 volts - electronic, 7 volts - electronic, 12 volts - points, 7 volts - points. I was worried about burning up the coil, but I've tried several spares too.

 

[rustybronco]

I'm starting to wonder if I should replace the whole distributor. Maybe my mechanical advance is screwed up. That's the only thing that hasn't been replaced!

 

[BBowski82]

No need to replace it, the advance can me replaced by itself. Also does Ford use a Vacuum advance?? if so, I have seen chevy vacuum advances rip diaphrams internally.

Best thing to do is just get it runnin, and then check base and total timing.

 

[rustybronco]

Thanks for the input, not sure if I'll be able to sleep tonight!

 

[BBowski82]

No problem...I like "bench racing" and troubleshooting

 

[Andy]

Put on an after market electronic distributor. I had the same problem, and unfortunately it happened when I was going to blow the doors off of a Wrangler. Needless to say I got beat by a Wrangler. I installed a Mallory comp 9000 and I gained gas milage and throttle response, not to mention better higher rpm's. That distributor was the best thing I ever did to that motor. And Brandon had it right from the first post, vacuum advance sucks!

 

[spencurai]

I am putting my money on the carb. my zuk was doing the same thing with its highly computerized carburetor so I ditched it for another one and everything is fine....


yeah mine happened when I was racing a kid on a tricycle......yeah I got beat by a tricycle....so what.....

 

[rustybronco]

Looks like we're down to the main 2 things: carb-spark. I think I'm going to try replacing the distributor first. With the electronic distributor can I do away with the ballast resistor and run a full 12 volts?

 

[xjc]

I'm certainly no expert but in my humble oppinion it has nothing to do with spark. With spark, ya either got it or ya don't. grab the wire and look for a blue spark. If its there forget the ignition.

I had a problem with a carb that sounded just like yours. My bet is that the float or some other meatering device (not familiar with that carb so I don't know if it has all the solinoids and crap) is stuck open. you're getting flooded!

Then ofcoarse I'm usually wrong on things like this

good luck

 

[rustybronco]

I know the carb isn't adjusted quite right yet, but I still go back to the fact that I have to advance timing over 50 degrees just to make it run. I'm positive I've got a spark problem, but what!? I've reset the distributor a few times now, even pulling off the valve cover to check for top dead center. I've got something weird going on but it's probably really simply too. Just can't figure out what. New distributor shows up tomorrow so we'll see what that does. Thanks for the input guys! Keep it coming!

 

[troutbum]

if it wont lean out and it is fouling plugs, I vote for the carb. Is this a new or newly rebuilt carb? The q-jets have a tendancy to leak at the fuel wells... usually just needs a little JB weld .

 

[BBowski82]

Hey guys, how do you figure it has anything to do with the carb if it wont idle under 50 degrees timing???? come on now. The fords are notorious for bad advances....And spence this carb is not computerized...its a quadrajet.

XJC--How do you figure you either have spark or you dont?? Ever heard of coil tunneling? or having a spark short? we aren't talkin about spark anyhow we are talkin about advance.

Troutbum is correct about the wells leaking on the Qjet, however you stated this is new from BCbroncos so I doubt this is the problem...

What it comes down to is that people are afraid of Carbs...like its some black magic to get them to work correctly. NOT!! the quadrajet is an excellent carb, especially for offroad!

 

[troutbum]

Originally posted by BBowski82
[B

What it comes down to is that people are afraid of Carbs...like its some black magic to get them to work correctly. NOT!! the quadrajet is an excellent carb, especially for offroad! [/B]

I run a q-jet, and unless I bounce it around a steep angles it does pretty well, and is an excellent carb, as far as carbs go. No magic to it, but you have to understand how they work....

Yeah the timing thing does not jive with the carb, , especially if it is new. And it is real tough to set A/F ratios if you can't get the engine to idle... but seems to me like there is more than an advance issue here if he can't lean the carb out once he gets to idle at 50*??? Best bet is to fix the idle/advance first and then try and tune the q-jet

Are you timing off the wrong wire
Hope the dizzy fixes it

 

[BBowski82]

Originally posted by rustybronco
Looks like we're down to the main 2 things: carb-spark. I think I'm going to try replacing the distributor first. With the electronic distributor can I do away with the ballast resistor and run a full 12 volts?

YES, the ballast resistor cuts the voltage to 6-9 V and your electronic ignition needs 12. IT HAS TO HAVE 12V TO WORK PROPERLY. by no means run the ballast resistor....if its on there now bypass it

 

[Milner]

Check all the vacum lines. Could be a a leak even further down in the vacum circuit that is causing a loss/change in vacum at the dist.. I agree with looking there first.

Was you dist loose at all, could it have jumped a tooth? Unlikely, but.....

I have seen vacum diaphrams only leak once things warm up.