Reproduction Parts for 1916-1964 Chevrolet Passenger Cars & 1918-1987 Chevrolet & GMC Trucks
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Hi everyone,
I ran into an issue with my 1938 Chevrolet Master while reinstalling the distributor. When tightening it down, the retaining bolt that holds the distributor to the engine block snapped.
I have a couple of technical questions regarding this setup and hope someone here can shed some light:
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Is the spring original? On my setup, there was a spring mounted under the bolt head. Is this original from the factory, and is its purpose to keep tension on the distributor so it can be adjusted/rotated slightly when loosened without slipping completely?
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Bolt Head: The broken bolt has a 3/4" head, which seems unusually large. Was this large head designed specifically to retain the spring properly?
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Thread Size & Replacement: Does anyone know the exact thread size for this hold-down bolt? Is it 1/4"-20 UNC, or something else?
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Temporary fix / Source: Is this bolt available from any specific vendors (seems Filling Station and Chevs of the 40s do not have it.), or can I temporarily use a standard hardware bolt (e.g., standard 1/4"-20) without the spring until I find a correct replacement?
Any advice, part numbers, or exact thread specs would be greatly appreciated!
Thanks in advance
From looking at the parts book it shows a shouldered bolt and spring. My guess is just tighten so the bolt bottoms out and the spring should keep the unit in place but allow movement as required by the vacuum control. Bolt size listed for 38 is 5/16-18x1-3/16. Part number 838089. You might be able to use a std bolt of the correct length and thread and substitute a spacer/tube over the bolt to act as the shoulder to retain pressure on the spring. The length of the spacer will be trial and error but possible compressing the spring 50 % would be about right.
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