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I have a 1978 ford inline six has a newer holley card having hard time adjusting it. Runs great at lower rpms and idel but when you drive it loses power and backfires.

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As you know, you have one of two things going on. it is running too rich or too lean. Run it hard for 15 minutes pull the plugs and check for black, wet looking soot = rich. Brownish, whitish dry looking soot = lean. Be sure your vacuum advance on the carb is hooked up to the proper port. Check the full advance of the timing with a light to be sure you have proper advance during rev up. You want 22 degs. full advance. If you have a pull choke try to close the choke to see if that will level out the hi end. If that works you are running to rich. adjust as necessary to lean it out. Too big a carb can also be your problem. For the best carb to engine size double the cubic inch of you engine. If your engine is a 290 ci you max size carb should be approx 550 cfm, Now if you engine has a hi rpm cam profile you have to factor in needed cfm at hi rpm. Thats why such and engine for racing will not have good bottom end or low rpm power. Sounds like you have just the opposite going on. Which can still be caused by a over sized carb. Too much fuel not enough air or room in the engine to burn it.

Posted on Sep 04, 2010

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Van stalls at low rpms but not all the time ?


If old van you have a carb. Jet plugged with trash. If you have fuel injection or throttle body injection, one or more of your jets is partially blocked. Try a cleaner added to your fuel tank. May end up replacing the part/s

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Sounds to me like you have the choke closing on you. Is it a electric choke on it? If it is closing it will do that. Loosen the screws on the round plastic canister and turn it till the choke flap starts to open farther. Keep adjusting it till it stops closing. There should have been instructions on choke adjustment with the new carb. If not do a search on google for Holley 600 choke adjustment.

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1986 dodge ram 225ci slant six and a single barrel holley carb


Start with the idle needle screw first, the idle mixture screw. Seat it all the way in, first-don't overtighten and damage it, just seat it lightly, and back out two full turns. Run the engine and set the adjustment by ear to get your best lean idle: start turning the screw in (clockwise) 1/8 or 1/4 turn at a time till engine stumbles, dies, or runs rough. Keep the engine running, and turn screw out (counterclockwise) a little at a time till you hear the idle dropping. Now between those two settings is your best lean idle. Turn the screw in, a little at a time and wait for engine to respond, tiill you get the highest idle speed. Now set the other idle screw, curb idle, to the idle setting for your truck, probably about 700 rpm. You can move back and forth between the screws to get the best steady idle. Just don't over do it on the idle mixture screw.
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1 Answer

I have a 1984-85 holley 4 barrel and it has


Electric fuel pump most likely has too much pressure for the carb. AFAIK, the Holley 4150/60 & 4165/75 should each demand the usual 4.7-5.3 PSI (4.7 @ idle, 5.3 @ max RPMs), so even the Holley red pump would need some restriction from a regulator. If you want this to be adjusted to its best efficiency, you need to have a fuel pressure gauge installed temporarily, if not on the regulator like I have on my Scout II. FWIW, the regulator I have installed is the Mallory 4307M from CenturyPerformance.com, Summitracing.com, Jegs.com, etc.

http://www.malloryperformance.com/pdf/4307M.pdf

A bad Needle & Seat will do this also, or debris stuck between the Needle and the Seat. This is where light tapping on the bowl helps, but it's best to run the fuel out of the bowl a few times and then the volume flow, or quick filling of the bowl, should loosen up the debris.

You also could have set he fuel float too high. What model carb, the ones I mentioned above (AKA Holley Modular Carbs)? If so, then Holley's site has a tech center & instructions on setting the float(s). www.holley.com

Set the floats carefully and slowly/gradually. Make sure the lock screw is always loose enough before turning the adjustment nut. If you strip out the bowl's threads on an older carb, you'll beat hell finding a replacement. 1/12 turn = 1/32" of fuel height IIRC. You set the fuel level, with pump running (wrap a rag around the carb so gas doesn't leak onto the manifold!!!) so the fuel is just starting to dip out of the "peep-hole" in the side of the float. Removal of the peep/seep-hole screw/plug is necessary first. Clockwise rotation of the nut lowers fuel level IIRC and counter raises fuel level. Again, please check their website. Most people get discouraged when dealing with the Holley Modular Carbs, but they are the simplest and the best carbs on the market. Even if 30+ years old.

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GIVE IT A FILTER CHANGE-AIR, FUEL. MAYBE PLUGS AND WIRES DEPENDING WHEN WAS THE LAST TIME. FUEL INJECTOR CLEANER, DON'T MESS WITH THE IDLE SCREW-THAT'S WHAT THE COMPUTER IS FOR.

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Carb is acting weird cant seem to adjust


That is the choke adjustment,have you checked your timing on the motor and check and see if the vacum pod on the distributer is working. also check your vacum lines for any tears or cracks in them.

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