1966 or 1967 Water Pump 3859326

[Donald H.]

I'm looking for the correct dimension/measurement for pressing on the blade mounting flange for the L79 water pump. That is the measurement from the back side (face of the block) to the face side of the blade mounting flange.

Thanks,

Don

[Wayne M.]

Re: 1966 or 1967 Water Pump 3859326

Might it be the same as for earlier years, as indicated on this table (Corvette column on the right) ?



c

[Donald H.]

Re: 1966 or 1967 Water Pump 3859326

Thanks Wayne.

I'm not sure. For some reason I though I read somewhere that for the L79 pump, this measurement was different. But I'm not sure where I read it. I'll check the pump I have to see how it matches up to the measurement in the table you provided.



Don

[John H.]

Re: 1966 or 1967 Water Pump 3859326

Thanks Wayne.

I'm not sure. For some reason I though I read somewhere that for the L79 pump, this measurement was different. But I'm not sure where I read it. I'll check the pump I have to see how it matches up to the measurement in the table you provided.



Don

Don -

'67 L-79's with power steering AND air conditioning (HP and HD suffixes) had the 326 pump hub flange pressed 1/8" further on the shaft, as noted in the 5th Edition JG, page 142.

[Joe L.]

Re: 1966 or 1967 Water Pump 3859326

GM cataloged two different short waterpumps in SERVICE for years, the only difference between them being a 1/8" difference in hub spacing (i.e one was 5-9/16" and the other 5-11/16"). The only problem was they never specified what applications each was intended for. Instead, they basically said "measure the replaced pump and buy the one that matches it".

[Donald H.]

Re: 1966 or 1967 Water Pump 3859326

Thanks all.

I have a rebuilt correct water pump for my 66 L-79 (no A/C or power steering) and I wanted to check the hub dimension. Looks like it is a little off. It measures 5 10/16". I'll probably end up using it as it. If it were to far on I could just use a gear puller and pull it out some. But to press it on more I would have to pull the back off and support the end of the shaft.

Don

[Chris D.]

Re: 1966 or 1967 Water Pump 3859326

The rebuilder's solution - split the difference and consolodate to one part number for both low volume applications. Probably works OK most the time. If your engine uses the same deep (and wide) groove pulleys as '63 - '65 solid lifter engines, then I would say your pump should target 5-11/16".

Its no wonder there are a lot of different opinions as the records are just not specific enough. '63 shop manual says "Note: Use end on Tool J-9608 except F.I. engines-F.I. engines use Tool J-9648 on step" and "Note: The factory specifications on this dimension carries a tolerance of +/- .005". No actual measurements are given. This record overlooks the carbureted 340hp engine which has the same pump and pulleys and must use the F.I. spacing. Otherwise the wider pulley hits the pump body.

That tolerance may have been on the pump assembly print but V-belts are much more foregiving than that. Besides, providing a tolerance without a base dimension is a rather silly comment.

I made some Ebay searches and aquired these tools just to see what they measured. 5.539 for the short stick, 5.684 for the longer item. Not exact fractional 16th inch conversions.

The subsequent '65 service bulletin sheds more light but still is not quite complete since, clearly, not all Corvette hub spacings were the same in the designated '55 - '65 year range. It also tells me that the spacing tolerance is not +/-.005" critical if the 5.539 design target can be serviceable at 5-9/16 (5.563).

At your stage in the effort, I would bolt it up and see how close your as-supplied 5-5/8" dimension lines up. If you need the extra 16th just apply puller and slide it out a bit.