1938 Hesitation
A Technical Tip from Buick Technical Tips

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 Hesitation (1938) -- On some of the first 1938 series 40 engines, you may experience a slight hesitation or flat spot acceleration at real low speeds. The correction for this condition is as follows: - Check ignition timing and spark plug gaps. - Check valve lash. - Refer to #31, page 143, in the 1938 Shop Manual and relocate accelerating pump nozzles so that the fuel streams hit the wall below the venturi, just above the throttle valves. It is not necessary to remove the carburetor in order to line up these priming pump nozzles -- it is only necessary that the air cleaner be removed in order to reach these parts.In the event that the above does not produce the ideal take-off, shorten the heat valve thermostatic spring 1/2" as per instructions in BPS 196, page 258. -- Paul Brennan, #9087. Reprint of Buick Motor Division Bulletin #34 published September 27, 1937. -- On some of the first 1938 series 40 engines, you may experience a slight hesitation or flat spot acceleration at real low speeds. The correction for this condition is as follows:
  • Check ignition timing and spark plug gaps.
  • Check valve lash. 

Refer to #31, page 143, in the 1938 Shop Manual and relocate accelerating pump nozzles so that the fuel streams hit the wall below the venturi, just above the throttle valves. It is not necessary to remove the carburetor in order to line up these priming pump nozzles -- it is only necessary that the air cleaner be removed in order to reach these parts. 

In the event that the above does not produce the ideal take-off, shorten the heat valve thermostatic spring 1/2" as per instructions in BPS 196, page 258. -- Paul Brennan, #9087. 

Reprint of Buick Motor Division Bulletin #34 published September 27, 1937. -- On some of the first 1938 series 40 engines, you may experience a slight hesitation or flat spot acceleration at real low speeds. The correction for this condition is as follows: 

  • Check ignition timing and spark plug gaps. 
  • Check valve lash. - Refer to #31, page 143, in the 1938 Shop Manual and relocate accelerating pump nozzles so that the fuel streams hit the wall below the venturi, just above the throttle valves. It is not necessary to remove the carburetor in order to line up these priming pump nozzles -- it is only necessary that the air cleaner be removed in order to reach these parts. In the event that the above does not produce the ideal take-off, shorten the heat valve thermostatic spring 1/2" as per instructions in BPS 196, page 258. 

Paul Brennan, #9087. Reprint of Buick Motor Division Bulletin #34 published September 27, 1937.

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