STILL Having Problems With The Lark-Advice Needed

[pitbulllady]

Well, I am STILL having problems with the '61 Cruiser running rough at low speeds-hesitating, surging, skipping and sorta sputtering, and wanting to stall out on stops unless I keep one foot on a gas a bit and one on the brake, which is sort of an aggravation with an automatic car. It does this as speeds that are below 40 m.p.h and gets worse the slower I drive. It stops doing this, though, as soon as I put the car in park or neutral-only does it in a motion gear. It makes no difference if the AC is on or not. It also stops doing it once I reach speeds over 40, and the faster I drive, the smoother it runs. I've done just about everything I can think of-replaced the softer rubber fuel lines with stronger, new lines, replaced the fuel filter, had the carb totally re-built with a Stude carb rebuild kit, by-passed and replaced the old original fuel pump(which was only putting out an inconsistent 1-3 pounds of pressure)with a new electric fuel pump, cleaned the points, completely cleaned and bored out the radiator and run in fresh antifreeze and temp reducer and replaced the old four-blade fan with a six-blade flex fan. The car is no longer running hot, not even in town in OUR weather(which was near 100 this past week)with the AC running full blast, and this problem occurs whether I've been driving it for half an hour or two minutes, before the engine even has time to heat up, so I don't think that vapor lock is the problem, especially not with the new fuel lines. It's also still "running on" a bit after I switch the ignition off, though not as bad as it did before the carb was rebuilt. Is all this possibly the result of modern gasolines, or just using regular unleaded? Will switching to a premium-grade gas help, or what about adding that lead substitute? Or, am I maybe thinking along the wrong lines by simply assuming it's something fuel or fuel system related? I wouldn't THINK that a faulty or worn-out generator would cause this, but then, I've never driven a car that had a generator as opposed to an alternator, so I could be wrong. Any suggestions as to what this could be, and how to stop it, would be greatly appreciated. It DOES idle very low when I put it in drive, then revs back up when I put in it park, though the idle has been adjusted several times.

pitbulllady

[bams50]

Has anyone checked for vacuum leaks?

Robert K. Andrews Owner- IoMT (Island of Misfit Toys!)
Parish, central NY 13131

http://www.cardomain.com/ride/2358680/1

[bams50]

Has anyone checked for vacuum leaks?

Robert K. Andrews Owner- IoMT (Island of Misfit Toys!)
Parish, central NY 13131

http://www.cardomain.com/ride/2358680/1

[GTtim]

I forget what engine you have, but with what you say you've done, I'd have the distributor checked out next.

Tim K.
'64 R2 GT Hawk

[GTtim]

I forget what engine you have, but with what you say you've done, I'd have the distributor checked out next.

Tim K.
'64 R2 GT Hawk

[PackardV8]

Greetings, pitbulllady,

If the car ran rough at low RPMs all the time, I'd look for a vacuum leak in the intake system. Could be gaskets, power brakes, PCV valve, distributer advance, carburetor shafts.

However, your saying it only runs rough in a 'motion' gear means it still could be a vacuum leak, but could be the transition circuits or the main jets. Remember, in gear, the engine is under load, and therein, isn't getting the proper air/fuel mixture and runs rough. Remove the load and it smooths out, so the idle circuit is good. The problem is still in the carburetor somewhere. Swap it out for a known good carburetor and tell us what happens.

thnx, jack vines.

PackardV8

[PackardV8]

Greetings, pitbulllady,

If the car ran rough at low RPMs all the time, I'd look for a vacuum leak in the intake system. Could be gaskets, power brakes, PCV valve, distributer advance, carburetor shafts.

However, your saying it only runs rough in a 'motion' gear means it still could be a vacuum leak, but could be the transition circuits or the main jets. Remember, in gear, the engine is under load, and therein, isn't getting the proper air/fuel mixture and runs rough. Remove the load and it smooths out, so the idle circuit is good. The problem is still in the carburetor somewhere. Swap it out for a known good carburetor and tell us what happens.

thnx, jack vines.

PackardV8

[railway]

I'm no tune up expert, so here is my penny worth. I think it has something to do with the vacuum advance. Now that said, could be on the carb side or the springs and weights in the distubator. Hole in vacuum line or pluged up or hook the wrong place on carb. Or the vacuum advance itself.

Ebon...

[railway]

I'm no tune up expert, so here is my penny worth. I think it has something to do with the vacuum advance. Now that said, could be on the carb side or the springs and weights in the distubator. Hole in vacuum line or pluged up or hook the wrong place on carb. Or the vacuum advance itself.

Ebon...

[sumf]

Poblem only in a "motion gear" to me means, "when loaded."
Yet, it goes well with the AC on or off.

Have you checked the compression readings since this began?
(Bad leak between cylinders came to mind.)

Good luck Karl

[sumf]

Poblem only in a "motion gear" to me means, "when loaded."
Yet, it goes well with the AC on or off.

Have you checked the compression readings since this began?
(Bad leak between cylinders came to mind.)

Good luck Karl

[Roscomacaw]

By rights, this car should have the superior Delco window distributor. That said, there still could be something wrong with it. Frankly tho, I'd be looking at the carb after checking for vacuum leaks.
Man, there's NOTHING tougher than thrying to accurately diagnose something as undefinable as this thru your computer monitor! Quite likely, one of us could take one listen - or drive - and say: OK, here's what it is.

Miscreant adrift in
the BerStuda Triangle


1957 Transtar 1/2ton
1960 Larkvertible V8
1958 Provincial wagon
1953 Commander coupe

[Roscomacaw]

By rights, this car should have the superior Delco window distributor. That said, there still could be something wrong with it. Frankly tho, I'd be looking at the carb after checking for vacuum leaks.
Man, there's NOTHING tougher than thrying to accurately diagnose something as undefinable as this thru your computer monitor! Quite likely, one of us could take one listen - or drive - and say: OK, here's what it is.

Miscreant adrift in
the BerStuda Triangle


1957 Transtar 1/2ton
1960 Larkvertible V8
1958 Provincial wagon
1953 Commander coupe

[studegary]

My guesses are a vacuum leak somewhere on the intake side (of course) or a pinhole leak in the steel fuel line between the tank and the fuel pump (or the flex line at the tank) drawing a small amount of air into the fuel. I do not believe that it is related to the type of gasoline and you do not need an additive or premium, in fact premium may make it worse. Your "running on" comment makes me also add initial spark timing as a possible problem.

Sharon - Through your local SDC chapter, search out someone, or a referral to someone, that is familiar with the mechanics of an older (pre-'80) car. This is the type of problem that should be easy for a real mechanic who has the car in front of him and can listen to and experience the problem as well as putting a timing light on it.

Gary L.
Wappinger, NY

1959 DeLuxe pickup (restomod)

[studegary]

My guesses are a vacuum leak somewhere on the intake side (of course) or a pinhole leak in the steel fuel line between the tank and the fuel pump (or the flex line at the tank) drawing a small amount of air into the fuel. I do not believe that it is related to the type of gasoline and you do not need an additive or premium, in fact premium may make it worse. Your "running on" comment makes me also add initial spark timing as a possible problem.

Sharon - Through your local SDC chapter, search out someone, or a referral to someone, that is familiar with the mechanics of an older (pre-'80) car. This is the type of problem that should be easy for a real mechanic who has the car in front of him and can listen to and experience the problem as well as putting a timing light on it.

Gary L.
Wappinger, NY

1959 DeLuxe pickup (restomod)