JL66REDCPE

This is a stock 427/425 with TI. I was at a show Sunday. I drove to the show and the car was running fine. As I was getting ready to come home, I tried to start the car and it was hard starting. Got it started however it would not idle at all. RPMs would drop to around 500 and car would stall. I had to keep the RPMs above 2000 to keep it running. Car would sometimes backfire when I gave it gas. Rough getting home but I made it by keeping the revs up. Car runs fine above 2000 rpm. I changed the oil the day before and this time I used Marvel Mystery Oil. I cant see how that affected it unless the oil thinned and got past the rings and fouled the plugs. I also noticed the car ran hotter than it should have on the way home and burned a ton of gas. My guess is one of the following; 1. Distributor hold down came loose and timing retarded 2. Bad vacuum can 3. clogged idle circuit in carb 4. fouled plugs

I did not think fuel pump as it ran fine on the way home above 2000 RPM I even floored it in 2nd gear when I was almost home and it responded fine.

I will work on it tomorrow -- Please add your thoughts and comments on the problem.

Tiros

My guess is #1

Mikado463

and that's and easy one to check .........

let us know what you find

6T7L71CPE

My cynical take would be sabotage by someone at the show.... did you leave it alone at any time? Check timing, plug wires etc that are easily changed.

63Corvette

Sounds like a "blown power valve" in your carb to me.

JL66REDCPE

Left it alone for about an hour while my wife and I got pizza. This was an all corvette show in Ocean City NJ. I would hate to think sabotage however in today's world -- who knows.

JL66REDCPE

Absolutely possible. I have another carb with a blow proof power valve that I can try sitting in my office closet.

JL66REDCPE

That is why it was #1 - my thoughts also especially since the hold down for 66 was basically just a piece of heavy wire. I have a 67 one that will be going on it if this is the case.

roberts427

sounds like the plugs. Why the mystery oil ??

JL66REDCPE

Heard a slight ticking and not sure it if it was a valve or the tach cable. Figured it could not hurt so I added a bottle of MMO. Drove it about 60 miles round trip to and from the show -- still have tap/tick.
Long story as I have not had a chance to investigate it further.

66BlkBB

I had the same problem with my car last year. Found out that it was a bad float in the carb. I started out to go home from a local car show and when I pulled up to an intersection the damn thing would not idle. In order to keep it running I had to keep the revs up and it still wanted to stall. Made it home, barely and left it for the winter. Did not find the problem til this spring. Not saying this is your problem but just one more thing to look at if it becomes necessary.

JL66REDCPE

Well the distributor had not moved and was tight. I am thinking power valve now. I am going to put the other carb on and see what happens.

JL66REDCPE

Update - I removed #1 & #2 plugs today and they looked perfect. No oil fouling and a nice tan color.

I did however notice a couple marina blue gas stains on the intake manifold. I use straight 100LL avgas which is blue however a much lighter blue. I am now wondering if the folks at the airport gave me the wrong gas. I am going to call them.

I called the airport and they said that the other gas is clear. Another theory ruled out. Sure looking like power valve.

Jeffs82c3

You never said if you are running points in your distributor or not, I would check them to see if they are opening and closing...

JL66REDCPE

This is a stock 427/425 with TI. Everything so far is pointing to a fuel problem

Tiros

Except for:

Bill Pilon

I learned about 50+ years ago that about 90 percent of fuel problems turned out to be electrical, unless contamination was involved.

Bill

JL66REDCPE

Hopefully this is the last update. I installed the refurbished carb that was in my closet this morning. Primed it with a little gas and she fired right off. Set the idle at 1K. Noticed I had MUCH improved throttle response. I will send the original carb for refurbish to the same guys that did the one I just installed. They have done a couple for me already and I have been very satisfied with their work. I may leave this carb on the car and put the original back in the box as that one is correctly date coded etc.

Thank you to all that commented.

survivor66

I saw your car unattended at the show. It was a perfect day with more vettes in one place than I've ever seen, probably 500+ lined up for a mile. Just wish mine wasn't stuck in a FL garage! Glad to see you solved the problem and thanks for reporting the solution.

JL66REDCPE

That is my favorite show of the season. You have to preregister to attend. Maybe next year you can get your car out of the garage and make the show.