Join Date: Jul 2016
Location: East-Central Minnesota
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
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?
'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