Holley Tuning HELP

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JGC403

JGC403

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I'm so close to getting my Duster (360, 4-speed) on the road again. Everything is pretty much back together, just some little odds and ends that need to be finished up. The Carb being one of them. Its a 80457 that was just rebuilt. We had a chance to start the car today and to see if we could get it to idle correctly, before we ran out of day light. It didn't. So for next weekend I would like to have a step by step on how to get this setup right.

This was all with the car sitting in the driveway, did not take it for a ride.

Tried to set the electric choke, but it wouldn't do anything. Not sure if its just cause we don't know how to set it or if something is wrong with it. We were monkeying with it before the the engine was fully up to temp. And it did have power.

This is what was going on, with the engine up to temp. I just put in a Auto Meter Tach, the car wouldn't idle below about 1400 rpm on the tach. If the idle screw was backed out until the idle dropped down to 1000 rpm, it would stumble then die.

As it was idling around 1400 rpm, I noticed it would hunt for idle a small amount. It would increase idle slightly then slowly go down again. The needle on the tach would show this but you could also hear the change in engine speed. Not sure what would cause this.

Last there was no bog or hesitation step on the gas and the engine would rev up instantly.

That's all I can remember now with what I experienced so far. I have been looking at videos on youtube, to see where I should start. First thing I'm going to dump some new fuel in the tank. The stuff that is in there is about 4 months old. We set the fuel bowls when the carb was being rebuilt. That's the first thing I'm going to check next week. Then I'll turn the idle mixture screws in all the way then back out 1.5 turns according to Holley.

Any more input I would appreciate it.
 
vacuum leak?

more than 1 issue going on with that install-- hard to diagnose with your brief description.
the guru's on here will need to know what cam was used-- how it is degreed in.

did this holley carb work on another engine?

the carb might not be big enough if you have a radical engine installed-- good luck but add more info to your question & help will arrive ,Lawrence
 
*Vacuum leak could definately be an issue. Is something unplugged?
*Timing could be an issue too. Too much initial. You could try setting up with vacuum advance plugged just like you would do for a setting a stock engine to stock specs. Without knowing how radical the engine is, hard to suggest more on this front.
* Size will not be an issue for setting idle even if you had a 440 cammed for a 4000-8000 rpm power band.
* Stop looking at videos by 3rd parties. Maybe they know, but many do not. Get it from the horses mouth -
Use the Holley Lit. for information: Instructions for your carb here:
[ame]http://www.holley.com/data/Products/Technical/199R7948-5rev6.pdf[/ame]
Holley also has some "how it works" info on their website.
Best for "how it works" is Holley Carburetors and Manifolds by Urich and Fisher. Urich was VP of engineering at Holley.

* Not neccessary to reset the floats unless the fuel levels are wrong. This is a good first thing to check. Do this by removing the sight plugs. Fuel should be just shy of dripping out.

* Choke has two adjustments. One is the choke itself. If its an electric choke - rotate the housing. ( Electric choke means that the heating of the bimetal is assisted by the electric resistance heating. ) The other adjustment is the fast idle and kickdown. If the throttle is hung up on the fast idle screw, the tip of the main throttle screw (aka idle speed screw) will not be touching anything.

* The 1.5 turns out on the idle mix screws is an OK starting place. But anywhere from 1/4 turn to 1.5 turns out is OK for final setting. Test: If the mix screws are run all the way in (gently!) and the engine is still running, then the engine is idle mix is coming through the transfer slots rather than the idle port. In this case, the throttle blade needs to be closed more. I don't think this is the heart of your problem since you state the idle speed screw is already completey backed off.

* The more sophisticated way to approach the idle speed screw is to make sure the transfer slot is just slightly exposed below the throttle blade. This requires taking the carb off and looking from underneath. If it the transfer slots opening looks square, its ballpark correct. Anywhere from .015 to .040" could be correct depending on the width of the slot and your particular engine needs, but square looking usually does the trick.
- Then adjust the timing at idle and fuel mix to get the best power and vacuum. When shifted into gear it may need a little richer than in Neutral. In gear is what is important. Since its a manual, I'd set up it in N and then only if its dying as you let it into gear tweak the idle mixes an 1/8 turn richer.
 
For your Holley electric choke issue:


Assuming that the choke is properly installed on the engine and functions properly.


You need a good 12 volt source for the + input. I like to come off the input side of the ballast resistor and use a piggyback flat terminal. This allows you to stack the terminals and then be able to remove the choke and wire later without any traces that it was there. The two post ballast resistor is easier to deal with this than the 4 post ballast.

For the two post ballast resistor. Unplug both terminals from the two post ballast. Then turn the key on to the run position. Gat a test light and connect the clamp to the negative (-) side of the battery. Poke both wires that you removed from the ballast and see which one lights up the test light with the wires disconnected from the ballast resistor. The one that lights up is the terminal you want to use for the positive (+) power into the electric choke. (Don't use any coil wires as the coil runs at 6 volts - not enough for the choke to function properly).

Then hook the negative side of the choke to any ground. Set the choke setting to somewhere in the middle of the adjustment and start the car and then tweak your choke setting so the choke butterfly is completely verticle when the engine is warmed to running temp. It my take a few good cold starts/mornings to get it all dialed in.

If you get the correct power input and adjustment to the electric choke, you should be able to go out on a cold morning, pump the gas pedal twice, start the car, and as soon as your oil pressure comes up, put it in gear and drive away without any stumble. I drove a 67 barracuda with a 80457 in the winter in Detroit (20°F to -20°F cold starts). The 80457 is a nice carb and should run great. Tip: Get the vacuum secondary spring assortment and put the short yellow spring in your vacuum secondary pod. This will allow the secondaries to kick in sooner and reach full opening by 6000 rpm.


I agree with the other posts that you may have other issues like a vacuum leak causing your engine to idle so high/rough. Look for vacuum leaks, and check your timing.
 
The 360 is bored 30 over, Edelbrock Performer intake, cam: XE268H-10, http://www.summitracing.com/parts/cca-20-223-3 , exhaust manifolds with dual exhaust, no crossover.

Initial timing was at 22* with vacuum advance disconnected, and idling at 1400rpm.

The carb is old, my grandfather had it on a 440 that was in his Ram. The carb had been sitting and moved around for about 15 years, before we rebuilt it.

I have the 4 post ballast resistor.

Thanks for the input.
 
My gut feeling is you have a vacuum leak.

Maybe the throttle shaft is wore out in the carb.
With the car running spray some carb cleaner around the base of the carb and intake and see if the idle changes.
 
Secondaries too far open? All vacuum ports on carb plugged? Remove everything vacuum related at the carb and plug it. Isolate the carb/intake tract. No pcv, no brake booster, etc.

Fuel pressure and float level set properly? Any fuel dripping from the boosters?

That should run pretty well with about 14-18 initial.

At 1400 it may have mecahnical timing bleeding in.
 
I agree that somewhere between 14-18 degrees for your combo, and that should be around 800 rpm with the vacuum hose plugged. It will take several iterations to get the timing and idle fuel mix to a point it makes the most power at idle and just off idle. A little harder to zero in with the 4 speed because you can't just put it in D with your foot on the brake and see if the rpms and vac drop or not. (dropping is because the engine isn't making enough power to overcome the added load. The less it drops the better)

If you're willing to pre-invest some time, use the method at the bottom of my previous post. That is, take the carb off to look at the transfer slot exposure. Then take notes as to how far out the idle speed screw is when the slot is about .020 and .040 showing. (A wire type spark plug gapping gage is a handy reference). Put it back on and try to adjust the timing and fuel mix with the transfer slot square. If you can't, then open the thottle a little more. from your notes you'll know when its getting out of acceptable range. This should save you a bunch of experimentation.

In this case, it is likely ported vacuum will be the best source for the distributor's vacuum. Experiment with both if you want.
 
So the idle mixture screws were all the way in. Backed them both out 1.5 turns, and got the idle down to 950 rpm, without doing anything else yet. That's all the time I had today. But tomorrow, I'll be playing with it more, want it to idle around 750 rpm.

The engine would idle lower, but the tach needle would bounce between 500 and 1000rpm if the idle was lower than 950rpm. The engine was maintaining its rpm but the needle was bouncing around. ???
 
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