Chevy small block water pumps Q?

I think they're all pretty much the same, but 60's cars had a shorter pump as you noticed, and later cars used a reverse rotation pump (which is really what you need to watch out for.) If you're sure that none of yours are reverse rotation, you're probably OK passing one on to him.

That said, they're probably under $30 at your FLAPS so putting a used one on might be false economy if it's more than an hour's work to replace it.

nate

The two that I have that are reverse rotation are still attached to the engines I bought. $50 for two late 80's small blocks mostly complete... too bad I can't use pretty much any of it on the race car - but they might end up being used as cores for the truck when it's rebuild time.

I just don't know why a 70-76 Camaro water pump is a different part # than a 78-81. heck, they probably take the same V-belt.

Ray

I think it has to do with the bypass fitting on the pump. Also they were rated for different flow volumes IIRC.

Do you mean the heater hose outlet? The small block pumps I'm looking at have lower rad hose and heater hose connections.

I keep reading there was a change in 77 or 78 across the line, but _what_ is the change? A 70 350 and 76 350 use the same pump, but a 78 pump uses a different OEM part #.

I'm thinking of actually emailing Summit.

Ray

If you have a friendly local parts place, maybe they would open different ones and let you see, measure, etc the differences. Other than physical dimensions, about the only thing that is normally in question is the direction of rotation, and you may be able to see inside well enough to be sure that is correct?

Length from mounting to surface of pulley hub.

Sure thing...that would be one of the important physical dimensions to check. If you had to use a different pulley, shaft diameter should be measured just to be sure it will fit.

are you describing the short/long water pumps? That's definitely NOT it. Some places list two pumps (short/long) and some list 4 (short/long and pre/post 78.) These are all "normal" rotation pumps. I'm trying to figure out what's the diff between a 76 and 78 350 Chev that would change water pump part #'s across the board. Summit is a non-reply so far and frankly no one seems to know and the pumps all look the same to me.

Ray

There are two different noses on the hubs also. 3/4" and 5/8" if memory serves me right.

I thought I remembered there being some different diameters involved in some of them.

I would be of the sort that would check the measurements, see if I could see built up areas that would suggest a stronger casting, and if it looked like a duck,and walked like a duck, and quacked, I would roast it.

There is a lot of interchangeability in some of those parts and parts numbers dont always spell out why changes were made.

Aha! Based on Summit's response, that appears to be it. I'm assuming the one size fits all pumps use the smaller size and don't worry about it? My race car has been through a couple of different fans and never had one be not fit.

Ray

The stub size was different on the Corvette pump. The long pumps all have the same size stub. I wonder if it has anything to do with having a fan clutch? The later years would have been the ones with smog motors and fan clutches. I believe the pump bearings and the seals were different as a result of the heavier load on the nose of the pump.