1979 400. Weiand intake straight up timing chain edelbrock 750. I want to put the edelbrock on a different motor and I have a motorcraft 2150 and a iron 2 barrel intake from a 79 f350. Bought the f350 with the motor apart from a friend of mines elderly dad 4 years ago. 5 years before that someone had blown the 400 in his truck up so it sat for 5 years in the cab then I bought truck and the carb sat in my garage for another 4 years.


My truck has had problems in the past with run on, but tuning the timing took that out.


Swapped the motorcraft onto my truck Friday and it starts fast idles good slightly less throttle response that the edelbrock especially in higher rpm. Feels like I’ve got a smaller carb on like it should I guess. Left my aluminum intake on and used a 4 barrel to 2 barrel spacer. The 4 barrel side is 3/4 an inch tall or so and open to both holes in the intake. So I’m not covering or mis aligning a carb or intake hole.

Problem is I turn the truck off and it starts to violently run on for several second before I let the clutch out and get the motor to stop. Previously when I had it to retarded it would spit and sputter for a couple seconds then die out real easy. This time it’s rocking the truck around big babooms all around.

I figure if all i changed was the carb it carb it might be running to rich. I haven’t sprayed anything through it like cleaner yet. It ran rough for probably the first 45 seconds but it cleared up as it idled. I figure that’s getting all the old hunk out but I don’t see how that could cause it to run rich other than a stuck needle or the float sticking up instead of coming down.


Ive got the Evap bowl on top plugged, the grill emissions line on the side plugged, the vacuum advance hooked up. I need a T to attach the booster and the pcv to the pcv on the carb so now I’ve only got my booster hooked to it and a red rag over my pcv hose. I’ve also got a bolt with some thread tape in the hole for the hard line going to the choke.
I figure it’s not the idle adjustments because it’s idling, starting, and running okay.

Does this sound like anything else than a stuck float or needle? And what are the chances I can clean those with today’s brake cleaner without taking the carb apart?
Can I measure the float from the outside and what should it be set at? I guess I’ll have to look up how to adjust that I’m assuming that will involve opening it up.

 

Hey Larry, you've probably seem, this before...I like to learn more about tuning my carb too

MOTORCRAFT 2150 - Gary's Garagemahal (the Bullnose bible) (garysgaragemahal.com)

Good Luck

 

mine runs rich as well. i cant tune a CARB to save my life.
i got it to a point where the choke works great but runs like garbage.
or it runs good and choke backfires up through the carb.
cant get it to a happy medium.

 

Sounds like a lean condition. You are running too hot allowing for detonation, 400s big open chambers are known for it. There is supposed an idle solenoid that helps, allows the plates to close fully when the key is off.

 

I have no solenoid. The engines only running for 3-4 minutes before it gets shut down and starts running on. I turned the idle up slightly and got it running smoother yesterday. It seems like just idling doesn’t cause much to happen but driving the truck does.


My oil pressure gauge pooped out on me at the same time. I didn’t touch the sending unit or the wire so I don’t know what could have caused that. When I get time I’ll make sure the gauge is working if it is then I’ll change sending units if that’s not it I guess I’ll hook another gauge to it to make sure it even has oil pressure. I put a pump in the engine 4-5 years or so ago.


i have been to that site before. I can figure out to adjust the floats in this and I can check the needles but didn’t know if something else could cause that to happen in the carb.