[updated:LAST EDITED ON 22-Nov-02 AT 06:22 PM (EST)]I have a 390 with a Holley streat avenger 770cfm carb. The problem is if I let it idle at a stop sign or when it is warmng up it will start to chug and some times die. I have tried to run it lean, rich, messed with the floats and checked for leaks. Nothing helps even the local mechanig said the carb is fine. The moter has only 6000mi on it and it just started doing this. Does anyone have any advice? I'm open to ideas.

 

My engine does the same but I know its caused from a weak ignition on a souped up engine. My neighbor just went from points to MSD dizzy, coil and 6AL. It ran poorly when cold on the stock stuff. Now it doesn't even know when its cold. Go with a high performance coil and gap your plugs out to about .050.

 

[updated:LAST EDITED ON 22-Nov-02 AT 10:54 PM (EST)]Hey another F150- you may have a bigger carb than you need. According to the formulas everyone uses, even a truly hi performance 390 should be running around 600-650 CFM carb. And the difference is at the low end. I have used both E Brock 600 CFM and 750 CFM, did not use the 750 for very long just for that reason, it was loading up real bad at lower speeds, it was purely a foot to the floor carb. And I'm now going to the 670 CFM Holley Street Avenger, so I'll have a report (someday) and will keep the 750 in reserve for drag strip. Yes the CACWBY will be going to the drags, (after some shows), I put in a driveshaft loop just in case. The Holley ads for the SA are misleading they use a HP chart and I was told by my engine builder it's more important to go by CI and volume and effeciency. I'll be posting some more in progree photos over the weekend. Trevor the CACWBY in WI

 

[updated:LAST EDITED ON 23-Nov-02 AT 00:30 AM (EST)]My moter is built very strong the heads are CJ rated and has about 450hp and I am runing a MSD 6A box and a Accel super coil. I will try a smaller carb but I dont think it will feed the moter enough.
Hey CACWBY nice truck what are the specks on it.

 

What are you idleing at it may be to low for you're 450hp??

 

I would dump the super coil. They are so bad they make both me and my neighbors tach jump as you hear the engine miss at low rpms. It seems to do alright at higher rpms.

 

I idel at about 1500RPM. but I figured out the problem, my choke was kicking in when I would stop so no more choke. but i have a new problem that could be just bad gaskets or maybe worse? I have smoke comeing out of the distributer o-ring and the oil fill nosel but I dont know why it is coming out of the oil fill. Any ideas?

 

I'd guess blowby if you dont have the pcv hooked up