Technical 1BBL Rochester on a '64 Buick Special

This is a weird one. Well, I think it is at least.

I've been chasing an issue with my '64 Special. The car sputtered to the point of wanting to die when navigating a LH turn, regardless of speed. The carb has good driveability everywhere else when the engine is fully warm, with the exception of a slight stumble on takeoff.

The carb is a new, re-manufactured unit. All the external and internal moving parts slide/turn/rotate freely without slop. I did a lot of troubleshooting and research (I verified idle speed, idle mixture, float drop, float height) and confirmed all were to spec.

It was really acting like the float height was set too high, and during left turns, fuel slosh inside the carb would flood it out. This was confirmed by accelerating through a LH turn - the higher air demand would reduce the sputter. So, I adjusted the float level down a little, and it got a little better. I adjusted it a little lower, and I got it to the point that it only sputters when navigating a LH turn at a fairly high speed. I can live with that I suppose.

The problem is, now that I've set the float low enough to provide good drivability, now I have a cold start issue. The car starts easily enough, but stalls when cold. And since the float level is set low, the fuel level in the bowl in insufficient to provide a "squirt" through the pump discharge. I literally have to start it, keep the rev's up, and let it idle for 10+ minutes before I can put it into gear and go. And if it happens to stall again, I physically have to pour a little fuel down the throat of the carb to get it restarted, since the pump discharge won't provide the squirt.

Is there an internal baffle that controls fuel slosh that I can add, so I can set the float a little higher? Is the accelerator pump discharge at all adjustable? I'm simply trying to get this thing so it will start, run, and steer without dying...


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I'd likely take that carb back to the store as a defect.


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Yup, try another one, see what happens.

Is it really a 2bbl? are there two throttle plates on the bottom, or only one?

 

This could be a problem they had from the start. AMC had the same type of problem with their 232 inline 6 cylinder. The way the carburetor was mounted caused the engine to stall on turns. I recall my dad saying the dealer installing a tapered plate to tip the carburetor slightly to one side to help with the problem. Maybe it would help in your case.

 

I owned a 61 Special a million years ago. It had the 215 V8, Rochester 2GC. I had a similar problem. Turned out to be a bad coil. Seems the oil in it would slosh to the other end in a hard turn and cause what you describe. Worth look....

 

I had that coil problem on a Plymouth years ago, the coil was mounted on it's side, it would die when turned one direction.

But fuel slosh symptoms are different from coil cutting out symptoms, to the trained observer.

 

Thanks for the replies guys. A little more info:

-Definitely a 1BBL (single throttle plate).

-I actually tried to rebuild the original carb before buying the remanufactured unit. I should mention that when I set the float to spec on the original carb, I had the same LH turn issue.

-I considered electrical issues (coil etc), but it's clear from resetting the float level lower and the subsequent improvement in turning, that the problem indeed lies in the carb.


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Strictly guessing here:

Rochester type B carburetors are infamous for casting warp where the bowl casting and airhorn casting mate. Casting warp, if present, can only be repaired using heat, and jigs to straighten the casting. Zinc alloy becomes malleable when hot, thus heat and a correct jig can undo the warpage.

There is a vacuum p***age in the divider between the two bowl sections. If the body is sufficiently warped, fuel could possibly be ****ed directly into the manifold, byp***ing the normal metering of the carburetor. This could create an overrich condition.

Some enthusiasts, and possible some carburetor rebuilders, might try to undo the warpage by filing, surfacing, milling, or other means of removing metal. This simply creates additional problems, as the thinner metal will again warp, but sooner. Plus, Rochester cast a "sealing ridge" on the casting to "bite" into the gasket and improve sealing. Removal of this ridge will cause leakage even if the castings are true.

Jon.

 

Interesting info, Jon. If the halves were warped, would I see fuel seepage externally?

 

Probably. Easy to tell if warped. ***emble without the gasket, and see if you can see light between the two castings.

Jon.