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FAST IDLE! 1966 Mustang coupe with Holley Street Avenger

6K views 15 replies 2 participants last post by  PBLA 
#1 ·
I recently bought an "A" code 66 coupe with a recently installed Holley Street Avenger 570(elec choke). The car has no tach so I can't say how fast it's idling but it does seem too fast. I'm no mechanic, but here's what I've tried and noticed, any help would be greatly appreciated. TRIED: bringing curb idle all the way down, checked throttle linkage, looked for vacuum leaks (admittedly a weak effort) NOTICED: There is no vacuum line to distributor (tried connecting it and it stumbled alot), the "choke fresh air intake" is connected to exhaust manifold. Again any suggestions would be appreciated.
 
#2 ·
Hello PBLA,
Several things.
1. - On the pass side of carb you will have an adjustment when the choke is being used. Look for a screw under choke housing. Perhaps it is in too far not allowing the regular curb adjustment to have affect.
2. Make sure the choke is wife opened (warm) and then can you lower the rpm's with the driver side curb idle screw. (This is near linkage)

To check for vaccum leak easily. Take a can of starter fluid or carb cleaner and spray it at the outside of the carb. Check near where the carb sits on the intake. If the engine speeds up...you have a vac leak.

As far as stumbling....when you hooked up the line to the distributor did you then adjust the curb idle.
I am thinking the line not being connected it=s like a vac leak.
Try these few things first and see what happens.......Print Dad
 
#3 ·
Thanks, curb idle is all the way down leaving no room for adjustment with or without vacuum advance connected. Could it be a timing issue? Also, should i disconnect the line going from "choke fresh air" to exhaust manifold. I understand this was necessary for autolite carb but isn't needed for electric choke carb.
 
#4 ·
Hello PBLA,
I would disconnect gas pedal linkage at the carb to be sure it is not holding the carb open.
I hope you understood what i was saying about the adjustment on the pass side of carb. It is possible that the back (secondary plates) are open a bit and thus the regular (driver side) curb idel screw can't do it's job.

I would not mess with timing as i don't think it is an issue. It could be checked with a timing light if you have one. Otherwise don't look for other trouble at this point.

Choke fresh air to exhaust shouldn't be a problem. it seems like he only logical solution is the throttle plate isn't closing enough which should be either the linkage or the screw on pass side. You should be able to idle the car down till it just about stalls.

Try checking these few things again. Post Back....Print Dad
 
#7 ·
I figured out for certain last night that the choke was getting stuck. I could manually shut it off, but when I would accelerate the car the idle would never come down again and the choke was stuck again. Disconnected the power source and jumped to battery much better! Now I just need to find a suitable place to permanently connect. Possibly wiper motor? Also I accidentally hit two posts with alligator clips and sparks flew for a while. This morning (about 80deg!) the car did not use the choke at all. Did I fry the choke or is it finally working properly? Oh yes I have been disconnecting my jumper to the battery when I kill the engine.
 
#8 ·
Hello PBLA,
Thanks for the update.
As far as a good source, you could run a wire to the fuse box that only is live when the key is on. A little experimenting and you'll be all set.

Chokes are great when they work but I haven't used on for man many years. I just pimp twice on a cold start and keep choke wide open. Aftyer about a minute the car starts to idle well on it's own.

I recently saw a post regarding power source for a choke on this forum about 2 weeks ago. A look back or a search may get you there for a few other ideas.


Good Luck and nice going figuring it out......Print Dad
 
#9 ·
Thanks, I'll check it out. More problems, choke seems to be operating correctly but now after idling maybe 2 minutes it will begin stumble worse and worse until it dies out all the while it's smoking and when it dies out gas is leaking from just below the secondary. What could be causing it to flood?
 
#10 ·
The car is very clean. A little rust on doors, but I did notice some rust in the filler neck? Is this normal? Is it possible there is trash in the needle valve? Would it be a good idea to change out fuel tank and filler neck? Thanks in advance.
 
#11 ·
Hello PBLA,
First don't get frustrated with this.

Starting with the stumble and stalling and gas leak. These are all sign of the needle and seat stuck open. Perhaps because of debris. I would take the needle and seat from the front bowl right out. Because it is a newer carb it should just need to be cleaned. Sometimes if you tap the top adjusting screw it will free the needle but it is just as easy to take out and clean. After re-installing you need to run car and check the level of the gas in the site screw. This is the screw on the pass side of the bowl. Remove the screw, (watch the little washer) and see if the gas is at the bottom of the screw hole. Turning the adjuster nut clockwise, will lower the fuel level. (Note: the screw is for tightening and the 5/8 nut is the adjuster. You put a box wrench on the nut and when adjusted, tighten the screw. There are several thin gasket washers there so watch them.

Now for the next issue. The Tank etc. Rust on the filler neck could be Ok but it is hard to say. These tanks build up rust and gunk that yo can't really see. What I would do first is.
1. - Install a clear filter before and after the fuel pump
2. - If possible blow out the line that goes from the tank to the fuel pump. This requires a compressor so you may not have one but OK
3. - Watch the clear fuel filters and see if they are collecting debris.
If they are, it could be time to replace the tank.

I bought mine at Mustangs Unlimited.

But it gets expensive to just change things without being pretty sure that it is a cause. Clean the needle and adjust the bowl height and see what happens.
You can get this fixed for sure........ Print Dad
 
#12 ·
Thanks, I needed a voice of reason and some encouragement! I did see a filter under the hood, I'll check it out before making a rash decision on tank replacement. What is the procedure for removing and cleaning the needle? Excuse my simple questions, but my limited experience does not include carbs or fuel injection for that matter!:headscratch:
 
#13 ·
Hello PBLA,
We all learn everyday.
Locate the screw and nut on top of the front fuel bowl. The nut is 5/8" and the screw is about 3/16 wide. You remove the screw (watch washer) then turn nut counterclockwise. This will lift the seat assembly. it has a rubber "O" ring. After backing off the screw, the whole seat comes right up. After it is out, spray with carb cleaner.

Check out this link from Holley
http://www.holley.com/TechService/FAQ.asp

It should help...also do a search around the Holley site. Print Dad
 
#14 ·
Cleaned the needle valve and it worked for about 10 minutes! Cleaned the filter and it was pretty dirty. Cleaned both needle valves and it's running okay. I'll replace the metal inline filter (which was new) with a clear one and monitor it as I decide whether or not to replace tank. If I replace tank and filler neck, I'll go with a kit that includes sending unit, but should I also replace fuel lines? Last question - You mentioned removing the screw completely then the needle valve assembly. If I back off on the scew as little as possible and remove everything together, then do the reverse, should the float levels be the same as before?
 
#15 ·
Hello PBLA.
You are close I think to getting this fixed.
As far as removing the needle and seat assembly.
The seat is screwed into the carb so you need to back off about
4/5 full turns. It doesn't just lift off. It needs to be unscrewed a bit first. You could count the number of turns whne you take it out then clean and re-install. This will make a lot moe sense when you do it.

As far as Tank - What I did was clean the filler neck, they get a bit expensive. if you do get a tank get a drain and sending unit.

As for the lines, I blew mine out and will watch them. The lines are about $75.00 from Mustangs Unlimited.

See you are learning everyday...Nice Going........Print Dad
 
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