Why is my 1962 Fleetwood stalling on hard turns?

[Matt Innocenzi]

Hello all and Merry Christmas,

I brought the '62 out for some exercise today and it occasionally stalls on hard turns, mostly when making a right turn.  Is my curb idle set just too low?  It only does it when warmed up and the choke is off, and I can't think of any other reason it would do it. 

Thanks for any advice!

Matt

[Chris Bryant #19358]

Hello Matt,

Just a thought. Have you been tinkering with the carburetor lately? Perhaps the float is sticking resulting in a low level of fuel in the float chamber.
I hope this sparks something off (idea-wise that is!).

Merry Christmas,

Chris Bryant #19358

[Matt Innocenzi]

Chris,

Funny you should say that...this is going to be a long story, but I think it is worth discussing. 

As a matter of fact, I have been fussing with the carburetor since March of 2011.  It has a Carter AFB.  The first carburetor I rebuilt had a bad vacuum leak and turned green in a matter of days with the ethanol in gas.  I put a second AFB on it but that one had a bad power piston so it was impossible to start it because it would not shoot fuel into the barrels.  I rebuilt the first AFB again and installed it.  The car seemed to run well except for the stalling issue on turns. 

A couple weeks ago, I started the car and it was blowing out completely black smoke and could not stay running.  I looked under the hood and the carburetor was dripping with raw gas.  I took it apart, and the floats were perfect;  the levels were on spec, the drop on spec, and they did not sink.  There was sediment in the bowls and in the filter which I cleaned out.  I re-assembled it, put it back on, and it ran perfect.  Now, it is having the stalling issue again.

In sum, I think you are on to something with the floats and needle valves, Chris.  But I can't get my head around what is causing those needle valves to stick open and flood the carburetor like it did a couple weeks ago and now, seem to stick closed and starve the bowls for fuel. 

I am a huge fan of the Carter AFBs but this one has me stumped.

Matt

[dadscad]

I've always thought that stalling on a turn was from too high of a float setting. I bet you still have some grit under a needle seat or a damaged needle and seat allowing the fuel level to rise too high. Sounds like on a hard turn fuel dumps out of the fuel bowl, momentarily flooding the engine.

HTH, David

[Matt Innocenzi]

David,

Excellent suggestion.  Just to clarify, when you say the float setting is too high, are you referring to the float level or drop?  If I interpret it correctly, I should raise both, the level and the height.

Before I do that, I want to check the flat settings that came with the rebuild kit to those given by Cadillac in the Technical Manual.  Does anyone know the float settings as published from Carter or Cadillac off hand?

Thanks all!

Matt

[dadscad]

You may have the float level properly set. I was thinking in your case, there may be damaged or leaky seats causing a rise in fuel level, because of the silt you found in the carburetor. My 63's shop manual has the float setting measurement listed for Carter and Rochester carburetors, used in 63. I would think your shop manual would list the setting. I think the old Motors Manuals had carburetor specifications listed also.

I discovered that I measured the float height in the wrong location the last time I rebuilt my AFB. I measured the height at the flat of the float half, midway from the seam and edge of the float. My floats were too high and caused heat soak percolation and hot restart issues. I reset them measuring from the seam and cured the issues I had after I rebuilt my cars carburetor.

HTH, David

[Matt Innocenzi]

David,

You may have just identified the issue - the location of where to measure the float.  According to the spec sheet that came with the rebuild kit, the measurements for drop and level are measured to the top edge of the float which is where I took them.  Your measurements are to the seam between the top and bottom half?  I will definitely look into this when I examine my shop manual.  I would expect the measurements to be a function of where they are being taken on the floats, so perhaps my measurements are correct for the location I took them.

Matt

[Jon S]

I had the same exact problem 2 years ago with my AFB.  The floats were set properly, but upon further examination the floats were not centered in the chambers and would bind against the outside "wall" of the carburetor.  I had to bent the hinged tangs just a spec to get them centered for the proper clearance.  No more stalling on right turns!  Take a look!  Good Luck!

Jon

[Scot Minesinger]

Matt,

Everyone is dying to see this car.  Merry Christmas! 

[dadscad]

The float halves in my cars AFB are joined in the vertical plane, not a horizontal plane. I measure from the gasket surface to the high point of the solder seam, not the horizontal flat surface from the seam out to the vertical edge of the float. There is a mention in the shop manual about the float being centered as Jon said. If the float is binding on the pivot pin or rubbing the side of the bowl it will affect fuel level. The legs of the float hinge pivot should slide between the pivot pin posts without binding or excessive looseness.

HTH, David

[Jon S]

The float halves in my cars AFB are joined in the vertical plane, not a horizontal plane. I measure from the gasket surface to the high point of the solder seam, not the horizontal flat surface from the seam out to the vertical edge of the float. There is a mention in the shop manual about the float being centered as Jon said. If the float is binding on the pivot pin or rubbing the side of the bowl it will affect fuel level. The legs of the float hinge pivot should slide between the pivot pin posts without binding or excessive looseness.

HTH, David

I am aware there is no mention of the centering but can tell you from personal experience that was the problem with my Carter AFB even though it performed fine before the rebuild. A simple adjustment and a permanent fix.

Jon

[Matt Innocenzi]

David,

Very interesting - my floats are all soldered in the horizontal plane, splitting the float into a top and bottom half.  I am going to check the shop manual and compare their settings to the ones that came with the rebuild kit.

Jon,

I would have never thought that. When I check the float level and drop I will check the lateral clearance as well.  Just curious, how were you able to check that?  When you were installing the air horn, just carefully check for rubbing or binding on the side walls?  I have a spare set of floats, I am thinking I may try them out.

Anybody have any suggestions on removing the entire carburetor or just the air horn to service the floats?  I like to keep it simple and be lazy, but don't want to take any shortcuts.

I will post what I learn (after Christmas) and continue to thank you all for your help and cooperation in getting this diagnosed!

Merry Christmas!
Matt

[Scot Minesinger]

Merry Christmas!

Just sent you an e-mail.  Have not found a way to service the floats other than remove entire carb.  Had to remove my 1970 carb so many times (don't ask), I feel like the fastest 1970 Cadillac carb changer East of the Mississippi.  You may become the fastest 1962 Cadillac carb changer East of the Mississippi.

Scot

[dadscad]

Jon, I attached the 63 shop manual page for adjusting the 63 AFB floats. Maybe the 62 carburetor had different floats in it, than the later years.

The AFB on my car is very simple to pull the top off. while the carb is still on the manifold. Remove the fuel line, disconnect the choke lever from the choke thermostat, disconnect the accelerator pump linkage and the fast idle cam linkage. Remove the power step up pistons and all the screws attaching the cover to the bowl. The cover lifts off with the float assemblies attached.

HTH, David

[Jon S]

David -

That is correct . . . same as for my 1958.

Jon

[Scot Minesinger]

If you have to disconnect the fuel line, choke linkage and a few other things, you might as well just remove the carb.  Time saved on the bench, not to mention better adjustments, will be worth it.  Plus you can accidentally drop something in the carb too and it is difficult to remove on the manifold.

[imf222]

Check your ignition sequence

[Matt Innocenzi]

Ron,

By ignition sequence, do you mean the firing order or timing? 

I pulled the carburetor last night and the floats still seem to be measuring properly and not binding on the sidewalls.  There is some more sediment in the bowls that I am having a tough time with, but otherwise, no visual problems with the carburetor. 

I pulled the plugs for inspection and they look beautiful with no fouling. 

Any other ideas?

Matt

[Scot Minesinger]

Matt,

Do you have another carb that is maybe OK that will fit and you could install to see if problem goes away?  If it does then you know it is carb, if problem is same, then you know to search elsewhere.

Have you looked at distributor counter weights, sometimes the bearing surfaces for the weights wear oblong holes where should be round and at low speed create a near stall situation.  That happened on my 1970 and of course it was blamed on carb.  Only figured it out after car would not start.  Greg wrote once that 99% of his carb problems are electrical.

Happy new year!

[David Greenburg]

Matt:

This may be a shot in the dark, but do you happen to have a PCV set up on your car?  I added one to my former '59 60S, using a later model carb insulator that had a PCV nipple on it, and after that sometimes had a "near-stalling" problem on hard turns.  I just lived with it since it took a pretty hard turn to make it happen, and it only actually stalled a couple of times; it just felt/sounded like it was going to.