andy's88

1950 olds 303 engine carburetor hesitates on acceleration any ideas will helpful.

dragline

Could you post a picture of the engine with the air cleaner off? Has the car been sitting? Accelerator pump cup may not be compatable with ethanol. Lots of possibilities. Any history?

andy's88

I rebuilt the carb but still doesn't run right

Tedd Thompson

Explain in more detail the hesitation you feel. Is it only on initial acceleration or any speed anytime. Have you checked that the accelerator pump is squirting? Was the new accelerator cup blue in color? There is a difference in light blue and dark blue but for the life of me I can't remember which was better for alcohol tainted gas. I do know there were 4 different type of accelerator pump cups, leather black and two blues, only one will hold up with today's fuel and some of the others will get soft and split just driving around the block a few times. Recheck everything you have done on your rebuild carb somewhere you have probably missed a step. Check for vacuum leaks around the base of the carburetor is a common one. Best of luck and keep us in the loop on what you find... Lost in the fifties ....Tedd

Ozzie

I'm assuming that it is a model AA 7002570 carburetor as was originally equipped. The Rochester carburetor book says the pump rod should be in the center hole for 1950. Then it says: Back off idle stop screw and fast idle screw so that throttle valves are fully closed. Remove pump rod from throttle lever and pull down to full allowable cocked diaphragm position. With pump rod directly under its hole in throttle lever carefully bend rod so that top edge of pump rod is flush with bottom edge of hole in the throttle lever. Reassemble pump rod to throttle lever. This ensures correct pump delivery at all speeds.

Tedd Thompson

Ozzy weren't there two different carburetors in 1949-50 I seam to remember seeing two different manufacturers/styles in the first years of the 303? or maybe they were just common swaps back then.... Tedd

Ozzie

Some of my books are at another location, so I'm a bit limited on doing research. The Rochester carburetor book shows carburetor number 7001570 being used in 1949 and number 7002570 in 1950. Both are model type AA. The adjustment specifications and tune up specifications are the same for both carburetors except for that pump rod hole location (outside for 1949 & center for 1950). The Oldsmobile parts book shows the 7002570 as the replacement carburetor for 1949 & 1950.

As you know Oldsmobile did use some Carter carburetors in the 1st half of the 1950s, but I can't find any that were used before 1951 or after 1955. Those were models WGD for the 2 bbl. and WCFB for the 4bbl.