Intermittent REALLY rough idle/running - Team Camaro Tech
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post #1 of 10 (permalink) Old Sep 2nd, 16, 07:30 AM Thread Starter
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Mark
 
Join Date: Jul 2016
Location: East-Central Minnesota
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Intermittent REALLY rough idle/running

Hello and thanks for peeking here, I'll make it as direct as possible.
The thing is 100% original. All original everything(pics in "My Garage"). 1968 convertible, 327ci, 210hp, 2bbl Rochester carb, 2-speed powerglide trans, points and condenser, carb not rebuilt.

When I drive the car 80% of the time, it runs like a dream. After a while, it may idle a little rough, but not bad. Last night I took my son up to the store 8 miles away; ran fine. Got in it to go home and was a little rough; by the time we got 8 miles back down the road to the gas station, I had to keep my foot on the gas at the stop light to keep it running. Got gas, let it idle while doing so to see what it would do. It shut off. Was only idling on 2/3 cylinders it sounded like/or like it had the biggest cam in it that you've ever seen. GIANT lope to it. Did that for about a minute, then died.

We limped it home and if I took my foot off the gas at all it would die. Starts right back up, but would not run on its own - it I got it pulled into the garage an let it sit. I went back out an hour and a half later to putz with it, and it fired right up and idled like a dream. Perfection. I shut it off and restarted it 4 more times and the same. Idled perfect; through drive and reverse also. Perfect. So I took it out for an 8 mile run...it ran, it accelerated smooth, it idled, and sounded perfect!

Now it's done this "a little" to me before, but not to the extent of it not running at all like last night...it has gotten a little rough at idling at times, but only slightly, and only after driving it down the highway for 10 or more miles. Seems to clear itself up after a bit of sitting though.

Pulled this car out of a barn a month ago, after sitting for 32 years. Got it running the afternoon we got it home. I've replaced many things, maintenance things, to make it a reliable driver, but most don't pertain to this so I'll not list them.

Things(possibly related to this issue) that I've replaced since buying it:
Fuel tank and lines
Air filter
Plugs
Plug wires

I put a new radiator in it but I don't know what temp it runs at as I just have the dash light(that's never lit up so I'm assuming it's temp is fine). I check it with the temp gun all the time(I keep it in the glove box) and it always reads in the 180's at the water neck, 150's-170's at the radiator.
I have not rebuilt the carb as the two front studs squish/turn with the nuts and I don't want to break them off just yet. I still want to drive it for a while before winter. I've not touched the points, condenser, or any vacuum lines, as the dang thing just seemed like it wanted to run.

One other thing I very recently noticed was a little bit of oil near the middle intake bolt on the passenger side, and slight oil residue near middle intake bolt on driver's side. Just started seeing that last week. I know it's fairly common but don't know if it would have any effect on the symptoms I'm experiencing.

It pulls 18" of vacuum at idle of 700 RPM. I adjusted the carb screws by turning them out to achieve highest idle, then in until it stumbled, then back out and then adjusted the idle down at the throttle/idle linkage screw. Have not checked dwell. It ran when we got it home so I went with it...

Any darn ideas? Coil? Vacuum leak?
Thanks!

'68 Convertible, #'s Matching, 327/210HP
LeMans Blue - Deluxe Parchment Interior
Power Steering, Powerglide, 10-Bolt, 2.73:1
Norwood car, Build date 03D

'53 Ford Crestline - Hardtop
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post #2 of 10 (permalink) Old Sep 2nd, 16, 08:26 AM
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Nick
 
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After sitting for that long it could be alot of things. Is the coil leaking any fluid?

Did you set your timing before you adjusted your carburetor?
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post #3 of 10 (permalink) Old Sep 2nd, 16, 08:51 AM
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Al
 
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Re: Intermittent REALLY rough idle/running

I would give it a complete tuneup (minus plug/wires) including a carb rebuild and a fuel filter.

You can remove those intake bolts, clean the threads, apply some thread sealant and replace - one at a time.


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post #4 of 10 (permalink) Old Sep 2nd, 16, 09:01 AM
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Nick
 
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Yeah. Old gas in the tank, fuel lines and carburetor turn into shellac when they sit that long.
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post #5 of 10 (permalink) Old Sep 2nd, 16, 10:08 AM
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Mike
 
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Re: Intermittent REALLY rough idle/running

If you just want to drive it until winter (October in Minnesota?) and then start to really figure it out, get some new points, condenser, rotor, distributor cap, vacuum advance can, and coil. Set the dwell and timing correctly. While you have the rotor off, make sure you have functioning springs and weights on your centrifugal advance. Change the fuel filter. Look for and address any major vacuum leaks including the loose carb studs you mentioned. That might get you back on the road for awhile and it's all dirt cheap and easy.

After firing mine up after 22 years of sleep by only replacing an old set of points with an even older set I had lying around, I drove it regularly while continuing to chip away at all of the things you'll need to address, including carb and distributor rebuild. Runs beautifully now.

1967 RS 327/275hp
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post #6 of 10 (permalink) Old Sep 4th, 16, 09:52 AM Thread Starter
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Mark
 
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New fuel tank and lines so that should all be fine.
I didn't check the timing at all, just rpm and vacuum.
I did find someonfo a out sealing up those intak bolts now. Thanks for that!
No fluid leaking from the coil.
Yeah, i thnk that's the next stop; coil, points/condensor, cap and rotor.
I wish i could get it to reproduce it, but cant do it on command.
I did however get if to fall on it's face yesterday by flooring it all the way down the on-ramp....guessing i ran the floatbowl empty.

Thanks for all the advice!
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post #7 of 10 (permalink) Old Mar 19th, 17, 10:27 AM Thread Starter
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Mark
 
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Re: Intermittent REALLY rough idle/running

Just an update to this thread should it be of use to anyone now that it's back to driving season here in MN.
I figured out that I "could" reproduce the problem and it had to do with the choke being sticky.
Mashing the pedal to the floor corrected it in the past when it would happen, and upon initial cold startup it would present with the same symptoms...one mash to the floor to "set" the choke corrected it. The choke would just stick on its own from time to time while driving. cleaning of the carb and linkage corrected the issue.

'68 Convertible, #'s Matching, 327/210HP
LeMans Blue - Deluxe Parchment Interior
Power Steering, Powerglide, 10-Bolt, 2.73:1
Norwood car, Build date 03D

'53 Ford Crestline - Hardtop
Raven Black/Sungate Ivory
239 Flathead V-8
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post #8 of 10 (permalink) Old Mar 19th, 17, 11:21 AM
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Mike
 
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Re: Intermittent REALLY rough idle/running

Nice reminder for me that the simplest things should be checked first. Now you can continue to drive it and address those other things. Good looking car.

1967 RS 327/275hp
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post #9 of 10 (permalink) Old Mar 19th, 17, 11:43 AM
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Mike
 
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Re: Intermittent REALLY rough idle/running

Glad you figured it out. Easy fix too
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post #10 of 10 (permalink) Old Mar 19th, 17, 12:46 PM
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Brian
 
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Re: Intermittent REALLY rough idle/running

Glad you get it worked out and ready to go Mark. It is always a good rule of the thumb for any car that has been sitting any period of time is to visibly inspect the carb for any tell-tale signs of leaking, sticking, rusting, and clean it out with some seafoam and or carb cleaner. Today's fuels are formulated to government guidelines that change throughout the season and areas of the country. Some parts of the country at times for the year there is more ethanol in the mix which evaporates faster and tends to leave a mess behind that will stick floats and clog jets. If she can't breathe she can't haul.


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