Stumble still present after new carb

[MoparMotel]

Sent out the original carter 4401 to be completely rebuilt and tuned the car Sunday after getting everything on. Some of you might remember my other thread on the edelbrock 750 stumble. Even after putting this completely restored and rebuilt carb on I still have an off idle stumble when leaving a stop sign or stop light. Also now with this carb when you floor it after about 4000-4200rpm it starts loosing power like its starving for fuel and stumbles a little. Any ideas besides carb? Timing is 15* initial, haven't checked total advance.

Thank you

[c00nhunterjoe]

What do you mean yu tuned the car? What jets are in the carb? How is the accelerator pump set up?  How much fuel pressure do you have at wide open throttle?

[Back N Black]

Did you check fuel pressure and fuel filter before the carb rebuild? Maybe the fuel pump push rod?

[MoparMotel]

I'll check the fuel pressure and total timing this weekend. Carb was rebuilt by old carb doc in north Carolina and set up for this motor. Not sure on jet sizes but you give him the info on motor and he builds carb accordingly. Fuel tank, fuel line and fuel filter are all new, fuel pump is 4 years old with maybe 800 miles on it.

[c00nhunterjoe]

In my opinion you can't send a carb out somewhere to get it "set up" for an engine, without the engine. 

[Cooter]

Sounds like you shoulda sent the whole car out to "Carb Doc".....

[b5blue]

Ignition first, before carb. Vacuum advance settings? Max advance and how is it curved? Idle likes a lot of timing, it's got to drop back as you accelerate and then climb back higher. That's a tricky dance, small adjustments can make a big difference. Are you doing testing under load (In gear.) or just in park/neutral?  

[y3chargerrt]

My stumble went away when I connected up my vacuum advance. I had to play with the adjustment in the advance can to keep it from pinging.

[MoparMotel]

Ignition first, before carb. Vacuum advance settings? Max advance and how is it curved? Idle likes a lot of timing, it's got to drop back as you accelerate and then climb back higher. That's a tricky dance, small adjustments can make a big difference. Are you doing testing under load (In gear.) or just in park/neutral?  

The car has the stock distributor with the exception of a Pertronix kit instead of points. I've checked the timing in park with the car idling and vacuum advance disconnected/plugged

[Cooter]

Pertronix=PITA

[c00nhunterjoe]

I've never used the pertronix. I assume it uses the factory advance and is just bypassing the points?

[MoparMotel]

Well had a friend come over that wanted a ride in the car so we took it out for a 30 minute cruise and it ran good- after driving non stop for 30 minutes we stopped at his friends shop and the car was shut off for approx 10 minutes. We went to leave and the car started kind of rough then died after driving about 50 feet. Would not start- looked inside the carb while hitting the throttle and had NO fuel coming out of the two squirters but the fuel filter was full of fuel. Had to have the car towed home. Took the fuel line going to the carb off and blew it out then put it back on and the car fired up fine. It had been sitting about 5 hours when i tried starting it again.

Did I have a vapor lock or is this related to the stumble/running out of fuel at high RPM?

[chargd72]

Well had a friend come over that wanted a ride in the car so we took it out for a 30 minute cruise and it ran good- after driving non stop for 30 minutes we stopped at his friends shop and the car was shut off for approx 10 minutes. We went to leave and the car started kind of rough then died after driving about 50 feet. Would not start- looked inside the carb while hitting the throttle and had NO fuel coming out of the two squirters but the fuel filter was full of fuel. Had to have the car towed home. Took the fuel line going to the carb off and blew it out then put it back on and the car fired up fine. It had been sitting about 5 hours when i tried starting it again.

Did I have a vapor lock or is this related to the stumble/running out of fuel at high RPM?

This happened to me a couple times.  After going the the carb and a couple fuel filters I traced it back to a small slit in the rubber line coming out of the sending unit.  Check the entire line from tank to carb thouroughly.  And if you don't find a break in the line, check again.

[c00nhunterjoe]

Soundslike vapor lock.