sbshafer2

Hello, obviously I'm new to this forum and have spent some time reading posts and familiarizing myself with the site. I recently bought a '68 four door cutlass supreme and am having a few problems with it. I had my eye on it for some time and decided to ask the owners if they would sell it. They told me to make them an offer it was her mothers car so I would be essentially the second owner for her mother bought it new in '68. From what I could see its in great shape only having surface rust. The interior isn't cracked or faded and is almost flawless other than needing cleaned. Amazingly it has 30,000 original miles and the only thing they new that was wrong with it when it was parked there 17 years ago was the radiator. I offered them $200 and they said it was mine as long as I promised to keep the leather key case her mother got from the dealer and I let her ride in it when I finish it. After three days of analyzing the engine and soaking the cylinders I got it running and it seemed to run like new but would drift off after a few minutes. I assumed the carb may just need rebuilding since its old and had been sitting. After the rebuild I discovered the rubber fuel line connecting the front line to the line into the tank was rotted and assume that it was my problem in the first place for the gas would go through it but leaked a lot of it leaked out. I then ran across the problem which I can't figure out and imagine someone here may be able to help with. The car will now start and run but only at a very fast idle nearly half throttle and will not run any slower without dying. I have tweaked the mixture and tried adjusting the choke to see if it made any difference with no luck. I also took apart the carb again but didn't see anything out of the ordinary. I have been working on old engines since I was a child and haven't had a problem that I couldn't work out after some time but I've hit a dead end.

Sorry for the length just wanted to get the full story in. I will post pictures when I go home next. Thanks

Indy_68_S

Welcome fellow Hoosier !

Not an expert, but I'd guess that your carb needs work. 17 years is a long time...lotsa things get brittle, dried out, or even gooey...You are using fresh gas, right ? When I dug mine out , the 20yo gas barely let it run, let alone idle. I drained most, mixed in a bunch of fresh, and when that finally hit the engine it took off and ran a LOT better...

Good luck

sbshafer2

Thanks. yeah I drained all the gas and put in new.took the carb completely apart and soaked it all in carb cleaner. I rebuilt it and replaced all the gaskets and such thats where im stuck. Since its been rebuilt and completely cleaned running fresh gas there's something wrong with it that I'm missing.

Indy_68_S

Ahh, I didn't realize you had done all that. (Reading comprehension > me) Disregard my post (well, not the Welcome part)...!

Someone else here I'm sure will have some ideas...

sbshafer2

Lol Its alright. Thank you for your welcome.

jensenracing77

another welcome from Indiana. i am not sure about your problem. there will be more ideas soon.

sbshafer2

Thanks

jaunty75

First off, let me add to the comments above and say that you have one cool find there.

Second, my totally amateur suggestion about your problem is that it sounds like your engine is starved for fuel. It sounds like your carburetor should not be a problem as you've done a rebuild. I rebuilt the carb on my '67 Delta over the summer, and it helped my car. What makes me suspect fuel is your comment that the rubber line coming out of the tank was leaking. My thought is that that was only ONE of the problems you might have in your fuel line between the tank and the carb.

Any possibility that the steel portion of the line is clogged or bent or kinked somewhere? Have you checked and/or changed the fuel filter? Are you getting good pressure from the fuel pump? How about the line from the pump to the carb? On my car, that line looked like it had been through the ringer a few times, with strange kinks and bends everywhere in it. The car did not have a fuel delivery problem, but I replaced that line, anyway, with a brand-new one from Inline Tube.

There's also a sock filter in the gas tank itself that might be damaged, missing, or clogged, especially if the tank had gas sitting in it for 17 years. Just siphoning out the old gas and putting in new might not be enough to clear a clog in that filter, and if that filter has fallen off or is damaged, crud from the bottom of the tank might have been sucked into the line and is now restricting flow. You probably don't have to take the tank off until you actually check pressure from the fuel pump, but if it's low and you can't find any other blockages or leaks, dropping the tank, cleaning it, and replacing that filter might be required. Another thought is to check the rubber vent lines for the fuel tank as that's how air gets into the tank as fuel is drawn out. There are two on my car's tank, and I replaced them both. If those are even partly clogged, fuel flow will be restricted.

A car needs three things to run: fuel, spark, and compression. It sounds like you certainly have the last two, but since you apparently have to keep the throttle wide open to keep the engine getting enough fuel to keep running, fuel supply is what you need to be looking at.



What you should have said is, "well, OK, but I REALLY wanted to use MY OWN keycase. If you insist that I use your mother's, fine, but then I want to pay only $100 for the car!"

Oldsguy

Welcome to CO. Sounds like the engine is running lean, as jaunty said look for fuel delivery/pressure or you could have a vacuum leak in the intake manifold. If one rubber fuel line was bad, you could have a lot of other vacuum lines that are bad as well. Just a thought, and good luck.

citcapp

May sound silly but did you change the fuel filter. Sometimes you have to replace it a couple of time because of the crud in the tank. just a thought

sbshafer2

Thank you all for your suggestions. I replaced the filter near the fuel pump and last I checked it seemed to be getting good pressure but things may have changed.

1ATony

Welcome to the site.

sbshafer2

I just thought of another thing to mention. When the car is running though it wont run slow it sounds fine when running fast....

68Tom

Welcome to CO. Sounds like you got a great deal.

Huh? Are you saying its idle is racing and when it does so it's fine? Not sure what you're saying here.

If it's racing, you did something wrong with the carb. Take it apart again and start over or send it out to someone who's an expert (not sure how experienced you are with a rebuild).

If it isn't racing but isn't getting fuel, chances are your fuel sending unit could be bad as well.

Just keep eliminating things off your list. Once that's narrowed down, you can pinpoint where the issue is. People have already given some good advice.

wolfman98

Welcome to CO. Hopefully you will find the answers you need to get the car running good.With mine it was pretty much the same story in that it would not idle even after warmed up. I had the carb rebuilt ( by someone better than me for sure ) plus I replaced the fuel pump and fuel filter. Then I changed all the vacuum lines and now she is really running nice. Keep everyone posted on your progress and you will soon get it narrowed down.
Nice find by the way , you can't complain about the price.

sbshafer2

Thank you all for the welcomes.

Well it wont run unless its running fast. To be more specific when its running it will only run fast but when it does it sounds like it has sufficient gas. However, when I try to slow it down much at all it dies. Thats where I'm stuck.

68Tom

That's because when it's idling at at the normal rpm, there's either not enough gas getting to the carb or there's a vacuum leak. So there isn't sufficient gas or air.

Here, check this out:
­'T­he goal of a carburetor is to mix just the right amount of gasoline with air so that the engine runs properly. If there is not enough fuel mixed with the air, the engine "runs lean" and either will not run or potentially damages the engine. If there is too much fuel mixed with the air, the engine "runs rich" and either will not run (it floods), runs very smoky, runs poorly (bogs down, stalls easily), or at the very least wastes fuel. The carb is in charge of getting the mixture just right.

­T­he carb is operating "normally" at full throttle. In this case the throttle plate is parallel to the length of the tube, allowing maximum air to flow through the carb. The air flow creates a nice vacuum in the venturi and this vacuum draws in a metered amount of fuel through the jet. You can see a pair of screws on the right top of the carb in photo 1. One of these screws (labeled "Hi" on the case of the chain saw) controls how much fuel flows into the venturi at full throttle.

When the engine is idling, the throttle plate is nearly closed (the position of the throttle plate in the photos is the idle position). There is not really enough air flowing through the venturi to create a vacuum. However, on the back side of the throttle plate there is a lot of vacuum (because the throttle plate is restricting the airflow). If a tiny hole is drilled into the side of the carb's tube just behind the throttle plate, fuel can be drawn into the tube by the throttle vacuum. This tiny hole is called the idle jet. The other screw of the pair seen in photo 1 is labeled "Lo" and it controls the amount of fuel that flows through the idle jet.

Both the Hi and Lo screws are simply needle valves. By turning them you allow more or less fuel to flow past the needle. When you adjust them you are directly controlling how much fuel flows through the idle jet and the main jet.'

Bobsw32

This can be a number of things.... First did you put points in the distributor and while you were in there did you check the mechanical advance to see if it is working they can rust in one position.... Then secondly this car is old...I would unhook and cap every vacuum line including power brakes and then try it...This will tell you if you are getting a vacuum leak..... Make certain you replace all the rubber parts of the fuel lines... They could be sucking air........Also did you replace the float when you rebuilt the carb?????They go bad also..... If all this checks out then I would see if I could borrow a carb from someone just to test it on the motor.....


By the way where are you in Indiana I am in Indiana also and have several spare carbs around that we could try..............


Just some thoughts from someone who has been there also

sbshafer2

Thanks. The distributor surprisingly looked like new. it was clean not so much as dust or anything in it at all the points still shined... I haven't tried capping off the vacuum lines though thanks for the idea. I should probably follow the entire fuel line to make sure nothing is damaged just in case. I did replace the float just to be safe. Judging by all the ideas I imagine that there is probably a vacuum leak somewhere or a problem with the fuel line.

And I live just west of Plymouth which is about 25 minutes south of South Bend. So Northern Indiana. Right now I'm in Muncie for college and only am home every other weekend.

Bobsw32

I am right down the road from Muncie in Ricmond...

I am assumuing the car is in Plymouth......

sbshafer2

Yeah it is.