Any carburetor gurus here? I need help

JBeezy

JBeezy

300B
I have a 1985 Ford F150 with a 351 Windsor. It has 69 Windsor heads on it with a Edelbrock 650 4 barrel carb.

The truck will crank and run. I'm having problem with it idling. It has an electric choke. It will crank up and run from a cold start. It kinda stumbles and misses at part throttle but runs out great when you press the throttle down. Anyone familiar with adjusting these things? Thanks in advance

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When did it start running poorly? I.E. did it start when you put the heads on it, or the carb, or did it just gradually start running like crap? Are you sure it's a carburetor issue and not a timing issue?

It's been a long time since I drove a carb'd car, I'm just throwing some things out there...
 
a_d_a_m said:
When did it start running poorly? I.E. did it start when you put the heads on it, or the carb, or did it just gradually start running like crap? Are you sure it's a carburetor issue and not a timing issue?

It's been a long time since I drove a carb'd car, I'm just throwing some things out there...
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We just put the carb on it a few weeks ago. It ran great with the old carb, but it sat up for a while and ruined it. Timing hasn't been touched.





martyo said:
Come visit us at the shop. Jeff is excellent with carbs!
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I would love to, but the next time I come that way will be to get my MM retuned

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JBeezy said:
We just put the carb on it a few weeks ago. It ran great with the old carb, but it sat up for a while and ruined it. Timing hasn't been touched.







I would love to, but the next time I come that way will be to get my MM retuned

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You're only an hour away and we are fun to see! :P
 
Zack said:
Rebuild the carb and see what happens
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The carb that's on it has been rebuilt. My buddy is pretty good at adjusting them but he has to work this weekend starting tomorrow

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So has it been adjusted since it was installed? If not then you need to adjust it.

Turn the idle mixture screws in until they seat, use light pressure do not crank them down. Then turn them out 2 1/2 turns. Then crank up the idle speed until it will keep idling. Slowly crank the idle mix down as low as it will go and still idle. Then adjust the idle mix screws in 1/2 turn each at a time. Does it run or worse. If it runs worse try returning to the 2 1/2 turns setting and back them out 1/2 turn at a time. If that doesn't help either try turning them all the way in. If it idles better with the idle mix screws all the way or almost all the way in then either the float level is set too high or the enrichment spring is too light for the amount of vacuum the engine makes.

If it starts running better at any of those settings reduce the idle speed and repeat until you get to the proper idle speed. Once you get to a point where turning it in or out more changes it back to worse go back and adjust 1/4 turn at a time.
 
I think I have it close. It idles better and I used your instructions. Thanks for that. I had it too rich and the off idle takeoff it was cutting out. I leaned it out 1/4 turn at a time. It keeps getting better. Do I need to up the idle screw as when I turn in the mixture screws the idle goes down a little?

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What you are shooting for is known as lean best idle. So that is turning the idle screws in as far as you can without causing it to start running rough/missing. As you get closer yes you will have to readjust the idle speed screw and then revisit the idle mixture screws to get it perfect.

I forgot to mention that Edelbrock has the owner's manuals for their carbs online and it details how to adjust it.
 
Nothing from Nothing but a word of advice on running Carb's

Last year I installed a New Holley Carb on a 1968 Torino GT that has a 72 Vintage 351 Cleveland 4V in it. I ran the car only once in awhile when the weather was nice , then let it sit in the garage the entire winter. Spring comes and I'm ready to start pulling the toys out.

I'm cruising along at 45 MPH on a street not far from my house....car starts stumbling , re-fires...goes a bit...stumbles ...dies at every chance to idle.

The Timing was perfect...Power Valve brand New , as was the Carb when installed. The car had Fuel Stabilizer in it to off-set any effects from this glorious Blended Gas we are subjected to , in my case it didn't work at all....money wasted.

After trying everything , it was time to take the Carb apart and start over. Immediately I discovered the fuel bowls were corroided to a white powdery point , much like Intergranular Corrosion you'd see on aged Aircraft grade aluminum. The Jets needless to say were clogged up with this. The Float was even discolored as this was a unit that still used a Brass Float.

Needless to say , I go out of my way to buy nothing but REAL GAS for any of my 4 Carbureted cars from that point forward.
 
Post #12 is 110 % right.
This rule also applies to small engines, lawnmowers, snowblowers, weed trimmers.
Thanks for that.
 
I watched a few videos from edelbrocks website and figured it out. Truck runs pretty dern good at this point. Need a carb expert to fine tune it though. I did fairly well for a first timer. I generally run no less than 89 in my yard equipment.

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I could clarify a little. The new gas adds alcohol. Old real gas does not. The alcohol dries out the rubber O rings and the paper gaskets then it leaks air. Cant add enough fuel to offset that. and as #12 points out it ate away at the metals in the bowl. That has not happened to me but the rest has.
 
Octane rating is peanuts in comparison to what Ethanol will do to something that wasn't designed for it. You will really need to go out of your way to find a station in your area that sells Real Gasoline.

In my humble expierience and from the results I've had to live with and pay for....all these so called Off-Setting additives are pure "Snake-Oil"
 
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