Engine HATES idling in gear. How should i keep it from loading up?

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1973 Q code Mach 1
At this point I'd pull the valve covers and rotate the engine over by hand while watching each rocker arm to see if your cam is getting full lift on each one. Also check that the pushrods will turn freely when the rocker arms are completely down. An over tightened rocker arm, or too long a pushrod may be keeping a valve from seating completely.

Perhaps I could point you to some carb theory that might be helpful

I don't agree with everything in the link I am sending, but the basics of how a carburetor works are worth reading through.

Dirt plugging a air bleed, jet or emulsion tube or improper float level can cause all sorts of problems

http://www.bob2000.com/carb.htm

(For the record I still think you have a vacuum leak)

If you did not use new gaskets on the carb, you need to and while it is off you should check the baseplate for warpage.

 

72HCODE

"My World is Fire and Blood"
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i little blurb about the throttle solenoid

the 351 V2 had idle issues that ford knew about,, to sort of band-aid the problem they came up with the throttle position solenoid.

the function of the solenoid was to raise up the idle base RPMS all the time except when you shut down the motor.

so at all times the idle was held high to smooth the idle, then for shutdown the solenoid turned off dropping the idle completely and prevented dieseling.

this was worse with open chamber heads engines also A/C cars needed it because of the extra load from the compressor. so the idle had to be held artificially higher.

the throttle solenoid has a different function then the choke.

but since you have changed the top end of the engine and have an edelbrock you no longer have the throttle position solenoid so that answers that.

i gave up on edelbrocks for our year cars, so i can only speak from a holley standpoint.

assuming no mechanical engine problems. you most likely need to fatten up the fuel on the idle circuit.

you should also hook up a vacuum gauge and see what you are making at idle. small changes can make a big deal.

you should think about spark plug heat range, Spark plug gap, initial timing, spark plug wires you are using.

these are going to effect the engine at idle. next is the carb. on a holley you can adjust the idle air bleed screws on a edelbrock you have meter rods that need to be changed. so you might think about picking up a edelbrock carb tuning kit that should come with more meter rods that you can try to swap out.

now you are running electronic ignition and that is fine, however you can toss out the instructions that tell you to add .05 gap to the plugs because of high powered coil and electronic ignition. .040" gap for a lot of our cars just does not work. stick with stock .035" gaping.

all tuning adjustment need to be done with the car in gear. so when you make an adjustment to check it put the car in gear with your foot on the brake.

you may find, you have to set idle at 1200RPMS because in gear the RPMs drop to 700rpms that can happen. now you may find that the combination of inital timing, high rpms, and hot motor will cause dieseling on shutdown, in that case you need to readjust all your setting for a much lower initial timing.

but if you are using aftermarket spark plugs or ignition wires(9mm,10mm, sprial core), take them off the engine and throw them right in the garbage they will cause more problems then you can imagine. you start with stock autolite or motorcraft 24-25 heat range plugs, stock carbon filament wires, any electronic ignition compatible coils is fine, gap the plugs to .035" and see what happens as a baseline. check your initial timing and vacuum readings at idle.

then you might have to get into the carb.

 
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1972 Fastback (Factory sprint, but now a bright red Mach 1)
351c 2v(big ol cam, holley dominator intake, roller set, edelbrock 4bbl)

fmx
I have an AFB carb. Anybody know any "rule-of-thumb" mixture settings on an AFB?

I'll have to doublecheck vacuum now that ive swapped manifolds.

I did not know that aftermarket wires could cause problems. I'll take a peek at the plugs and timing.

Last thing, Where do you guys have your idles set in park? I know it should be under 1000 but id like a more specific target if possible.

Again thanks for your wisdom!:D

 

72HCODE

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honestly its impossible to anwser what is a correct idle rpms because of part and cam combinations.

i can tell you i have to set my Idle RPMS out of gear at around 1000RPMS

in gear i'm around 850, if i turn on my AC it might drop to 800. it was the only way to not have the engine stall out if i lock up the brakes.

the manual tells you 650 rpms at idle in gear for an automatic and to add 50 rpms for AC cars, for manual they tell you 700-725 rpms.

but what dictates the rpms is the motor and load after you tried all manner of tuning and nothing works.

exhaust backpressure has a big effect as well.

if you have a 351V2 and go from single 2.25" exhaust to a dual 2.5" exhaust the back pressure will be very low and cause all kinds of idle weirdness. the engine can flow too well and clevelands are known to have low end problems. so that can cause the engine to run high rpms out of gear and in gear drop 300rpms and stall out.

As for air fuel mix, the idea is you aim for max vacuum under a set rpms and load. so you would set idle to what you think is correct and put the trans in gear foot on brake with headlights on. then you start to set the air fuel mixture until you see max vacuum then drop off 1-2HG for saftey,, max vac is lean.

then you go for a drive,,, what you always find is you can pretty much ignore that because you will have to fatten it up anyway to compensate for weather air temp etc...

so basically have a buddy sit in the car,, as above and you lean out the screws till she starts to stall then open it back up 1/8 of a turn until it stabilizes.

oh just make sure when you start to do all these changes that the vaccum advance is disconnected and the hose plugged off. when you finalize the settings then put the vacuum advance back and you will need to start adjusting that separately.

 
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