[powernote]

Hello, I have a 1967 Mustang Code C with 4bbl 600cfm edelbrock carb, and dominator intake. When the car is in idle the rpms drop and then go back to normal over and over again. In intervals of 2 seconods. It seems like the car is going to die everytime. Once I press the gas to the rpms stay. Also when the idle is rough my gas, temperature, and oil gauges don't stay steady. Sometimes when I get off the highway and arrive at a stop my fuel and temperature gauges read maximum and then go back to normal. Also when i just start the car my gas gauge reads maximum for a little bit and then goes back to normal. Could this be due to a bad voltage regulator or distributor? Any suggestions? Thanks.

[rocky289]

Yes.
A faulty voltage regulator can cause fluctuations in the gauges.
A worn distributor can cause a fluctuating idle.

[Bob A]

I would check for a vacum leak, check idle is it set to low, timing and points. As far as the gauges sweeping full and than normal. This is normal. I believe when your idle drops the alternator doesn't deliever enough voltage and your gauges go back to that test mode like when you first start the engine. I would get the idle resolved first and your gauges are properly fine.

[GimpCow]

Turned out to be a vac leak on mine...well when I say leak I really mean I forgot to plug an unused vac port, but plugging the leak certainly fixed the issue.

[jayz89]

I kinda have the same issue... it doesnt idle rough when the engine isnt hot... but once the temp gauge gets up to about the half way point and I drive at that point for a good while... it starts to sound like it wants to turn off and most of the time it does... because the rpms get too low or something. but its only a problem when im stopped and in drive because once I put into neutral or park it stays on fine.... any idea what it might be? it seems like all locations where a vacuum plug is needed there is one...

[GimpCow]

Turn your idle screw in a bit, should take care of it.

[jayz89]

ok I did that but still having the same problem...so before it gets a chance to turn off I put it in neutral and rev it up and when I put it back in drive it last a couple minutes longer before it starts getting rough again. is there anything else I should check?

[jayz89]

I was thinking of getting my carb rebuilt... or is there something else I can do myself that could fix this... its not that big of a problem but want to get it fixed asap... just spent a bunch on the cooling system.

[powernote]

Thanks for all the replies. I turned the idle screws a bit before, but the problem is still there. Not as much, though. I am going to do an electronic conversion on my distributor. I think its time for a tune up for the distributor. Another reason for erratic idle someone might have is the carb is plugged with gunk from a rusty gas tank or a plugged fuel filter. This might help someone else.

[jayz89]

cleaned out the carb but when it heats up still starts to idle bad... where are all locations for vacuum plugs? I would take a picture but dont have a camera.

[jayz89]

ok found out that it was actually just my transmission because it just dropped all of its gears. except for 3rd.

[jayz89]

okay tranny is good again... but problem is still lingering. any other suggestions would be largely appreciated.