Creating a correct 3859326 '67 L-79 water pump

[Bob S.]

Please forgive me if this has already been discussed.....

Searches reveal discussions of the need to disguise the presence of a bypass port reducer for judging since the correct 1/2" NPT housing is much rarer than the 3/4" housing.

Is it possible to convert a 3782608 to an external bypass configuration with a 1/2" NPT port? Might this be an easier way to achieve correctness since the pump casting number isn't visible for judging?

Thanks,
Bob

[Joe L.]

Re: Creating a correct 3859326 '67 L-79 water pump

Please forgive me if this has already been discussed.....

Searches reveal discussions of the need to disguise the presence of a bypass port reducer for judging since the correct 1/2" NPT housing is much rarer than the 3/4" housing.

Is it possible to convert a 3782608 to an external bypass configuration with a 1/2" NPT port? Might this be an easier way to achieve correctness since the pump casting number isn't visible for judging?

Thanks,
Bob

Bob------


Trying to convert a GM #3782608 casting to external bypass, if it could be done at all, would be WAY, WAY more difficult than just converting a 3859326 casting from 3/4" NPT to 1/2" NPT in a non-discernable way. To do the latter, install the conversion bushing so that it's flush with the top of the surrounding boss or just SLIGHTLY above. Fill any gap between the OD of the bushing and the casting with an epoxy like JB Weld or braze. Grind the area smooth so that no vestige of an interface between the bushing and the casting remains. Paint the waterpump with the engine. Done.

[John H.]

Re: Creating a correct 3859326 '67 L-79 water pump

Is it possible to convert a 3782608 to an external bypass configuration with a 1/2" NPT port?

Probably not. There's no boss on the 608 pump to accommodate the fitting, and the 608 pump isn't ported internally for the bypass function.

[Bob S.]

Re: Creating a correct 3859326 '67 L-79 water pump

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Thanks,
Bob

[Joe L.]

Re: Creating a correct 3859326 '67 L-79 water pump

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Thanks,
Bob

Bob-----


A GM #3782609 is one of the most hard-to-find and valuable of all Corvette waterpump castings. I don't think you'd have any trouble trading it "straight across" for a ORIGINAL, CORRECT 3859326. However, why do that? As I described above, you can rather easily create a correct appearing 3859326 from one of the easily available 3859326 castings with the 3/4" NPT bypass fitting. Then, you could keep the '609' or sell it for some big money.