1967 Idle Surging And Sticking - Ford Mustang Forum
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post #1 of 23 (permalink) Old 08-28-2019 Thread Starter
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1967 Idle Surging And Sticking

Hello all this is my first post so please bear with me as I describe a little background on the issue. So, it started out where when driving along around 30 - 40 mph and I would let off the gas to just cruise through a neighborhood or something. I would feel the car kind of 'catch' or 'lurch' as it came down in speed. It got more noticeable as time went on, then I noticed as I was coming up to a stop (with the clutch in or just in neutral) I was having to pop the gas pedal a little to get the idle back down to idle (it wasn't sticking high, just wasn't as smooth as it used to be). As you would assume there are the most obvious things I've checked such as adjusted idle screw, sprayed carb cleaner in carb, etc. This car has been converted to a 4 bbl intake and carb (carb is edelbrock 600 cfm and intake is edelbrock performer I believe), also there is a spacer of sorts between the intake and carb (thicker than a gasket but almost same material) that I've replaced. Fast forward a few weeks of this...now when I come to a stop (car in neutral or clutch in) the engine is almost out of control and revving up way too much to just be an inconvenience. I am at a loss here and honestly just need some advice on where to start on fixing this from the very beginning of things to look for. Any help will be absolutely awesome! With the weather cooling off finally I just want to be able to drive it lo. Thanks in advance!

PS...The car will idle ok if just starting in the driveway and warming up but I have noticed that if I let it idle for longer than a few minutes that it will randomly die as to where before I could let it run for like 10 minutes if I just wanted to let if I hadn't driven it in awhile.

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post #2 of 23 (permalink) Old 08-28-2019
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That is a weird one, have a look at your choke, it could be getting stuck 'ON' somehow.
Check that the linkages for it aren't catching on the air cleaner base.

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post #3 of 23 (permalink) Old 08-28-2019 Thread Starter
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Thanks! It does have the Edelbrock air cleaner on it...where on the base of that would I be looking for it to get stuck?
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post #4 of 23 (permalink) Old 08-28-2019
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Is there a dashpot on the throttle linkage? I've always had issues with those, giving similar symptoms. If so, just adjust it out of the way.

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post #5 of 23 (permalink) Old 08-28-2019
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If you have point style ignition, I'd check the point gap/timing. How about the fuel filter? Has it been changed? It sounds like you have multiple issues here. I'd also check for sticking linkage (causing high idle) by disconnecting the gas pedal linkage at the carb and see if the idle drops. And as above check your inside your automatic choke for sticking and the dashpot if you have one ( they are designed to slow throttle response when you come off the gas pedal). A partially clogged fuel filter could cause a low idle/dying issue.
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post #6 of 23 (permalink) Old 08-28-2019 Thread Starter
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@ Yadkin: I don’t believe I have a dashpot if so where would it be?
@ Travis: This sounds silly but how can I tell if it’s a point style ignition? I know it’s a electronic ignition and distributor. I will take the throttle linkage off the carb and see if there’s any movement. The sticking doesn’t happen until I drive so it’s hard to track this down lol.

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post #7 of 23 (permalink) Old 08-29-2019
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Quote:
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Thanks! It does have the Edelbrock air cleaner on it...where on the base of that would I be looking for it to get stuck?
If it is an automatic choke carby then the arms that make the butterfly open could get stuck on the air cleaner base.
If you are looking at it from the front the arm should be on the left side. just cycle it up and down to see if it is fouling on anything.

15/5/1964 260 Manual Coupe.
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post #8 of 23 (permalink) Old 08-29-2019
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Quote:
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Is there a dashpot on the throttle linkage? I've always had issues with those, giving similar symptoms. If so, just adjust it out of the way.

I agree it could be the problem, but if the car has an automatic transmission, I wouldn't advise driving w/o one. It's there to keep the engine from stalling if the throttle plates slam shut, as they may do in a quick stop. I know from experience that it will happen, since I drove my '66 w/o a dashpot for several years.

If it's causing the problem, I'd replace it. On my old 2-barrel and current 4-barrel carbs, it's toward the front of the carb; should be obvious.
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post #9 of 23 (permalink) Old 08-29-2019 Thread Starter
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@ Tony 64 - I checked the arms on the automatic (electric) choke with the air cleaner on. It moved freely and didn't catch on anything.
@ Charles Reeves - This car is a manual 4 speed...does that mean I would not have a dashpot?

All - Thank you so much for the input thus far! This weekend I am planning on taking the carb off and putting it on the workbench. Going to take pressured air and some cleaner to it...maybe it's dirty where I can't see. Question....Between the carb and in the intake is about a 5/16" gasket that my research shows as a heat insulator. Is that necessary? Is it better than a regular gasket? Haven't come across it before lol. Also one more question (for now hehe)...I am highly considering just selling this carb and going with a Holley. For the issues that I am having, and saying I eliminate out a bad carb, is there anything else that I should be looking for as the problem? The fuel filter is new and the fuel pump seems fine because I have no hesitation when I press the gas pedal or move the throttle. Just a thought I was having :-)
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You can probably make your existing carb work fine, but if you're burning to get something better, don't grab a Holley. Get a 600 CFM Summit M-series carburetor. You'll pick up several MPG and a whole lot of power down low, thanks to the better atomization from the annular boosters. It'll run smoother and make less pollution. Top end will be similar to the others, but why spend more for less? They're inexpensive too.

As for a heat insulator, Edelbrock carbs are pretty bad about boiling over. Most carbs are, with modern gas, and the high alcohol content. Using a phenolic spacer is best if you have the room for one, but a 'thick' gasket is all right. Since you are talking about taking the carb off, you really should replace that gasket anyway, and I wouldn't spend the money for another - so long as you have something there to help insulate.

Out of the many suggestions you've gotten so far, choke operation is the big one I'd look at. Best wishes!

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post #11 of 23 (permalink) Old 08-29-2019 Thread Starter
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@ Grimbrand - I will definitely look into those carbs! I am not too picky about MPG but hey less expensive is good! Haha. On the choke operation....Before I left for work this morning I was looking at it...if my ground is messed up/old for the electric choke can that cause the issues? My ground wire goes into a wiring harness and does not ground out on the carb like I've seen elsewhere. The terminal for the wire did seem a bit meh lol.
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It should be grounded to the carb and the other wire plugs into the harness. These auto chokes are adjustable.
Have you taken the air cleaner off and start the car cold to see the choke operate?
It should only take a couple of minutes from being closed to about 3/4 open, a blip from the throttle and the flap should stay wide open.
If this is not happening you can adjust the choke from the circular canister with the thermal spring inside. Most carbs have a + or a - to dial in proper operation of the choke.

15/5/1964 260 Manual Coupe.
23/3/1965 289 Manual Fastback.
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post #13 of 23 (permalink) Old 08-29-2019 Thread Starter
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Quote:
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It should be grounded to the carb and the other wire plugs into the harness.
So I should prob disconnect the ground that is currently on it and make my own connecting it to the carb? Could it be something as simple as a bad ground?
It wouldn't be the first time I've fixed something on a car just because of a ground lol.
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Doesn't anyone rebuild and tune carburetors anymore? Back in the day I would buy a rebuild kit and take mine apart about every 3rd oil change, clean it, blow it out with compressed air and reassemble, adjust in under 30 minutes. The kits come with clear instructions and there are several adjustments to be made on the bench, then finally on the car.

A new carb probably needs several adjustments anyway. Sure it will run, but I always had my old cars running perfectly, no hesitations, bogging down, all with low emissions and good MPGs.

And don't forget the ignition tune. Even if you've done a points conversion, its a good idea to check the mechanical and vacuum advance mechanisms for smooth operation. Correct plug gap, solid electrical connections an grounds...
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Pictures of your carb set up will help us help you.


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