boltnut

My pump has a 3/4" shaft. Do I need the same when I replace it ? All the ones I see have 5/8" shafts.....except for the one that cost 5x the price of a 5/8" pump. It has 3/4" shaft...

MelWff

Assuming everything else is stock you need a short pump with a 3/4 pilot to fit your fan and fan clutch. Where are you looking for the pump, have you tried any vendors from this site?

aussiejohn

boltnut,

The Corvettes also have a unique "length" water pump, so make sure you put your old pump down side by side with any new pump you intend to purchase and make sure it's the same.

Regards from Down Under.

aussiejohn

boltnut

Ok....they looked up a "vette" pump but it was advance auto. My pump is about 5" from the block surface to where the impeller shaft comes out of the pump housing. Is that a short pump ?

Peterbuilt

boltnut

So. The 3/4 shaft only comes in short pumps ? And the 5/8" shaft is a long pump ?

They listed a normal pump at 30....an HP pump at 120. And some other pump listed as "P" for 80. All same base part number and part jockey could not tell me the difference.

MelWff

go with this pump

http://www.summitracing.com/parts/BRA-1683/

Mike Ward

5/8" shaft is for pre-71 Corvettes.

noonie

Napa has the correct new pump #TFW 43104 for 52 bucks

Have gotten vette pumps at Autozone before.

boltnut

Screw it. I got a 30 dollar remanufactured pump from napa. It's a GM housing. I'll roll this time and see what happens. It has the 3/4 shaft and the 5" snout.

Now tell me about those plugs/bosses on the tops of these pumps. What's that all about ?

larrywalk

There are 3 SBC water pumps for the Gen 1 engine - the short, the long and the Corvette short pump. As seen in previous posts, the corvette pump from '71-'82 is slightly longer than the short SBC pump (by about .150") and has a larger shaft (3/4") than the short pump which has a 5/8" shaft.

If you try to use a short SBC pump in a '71 or later corvette, you'll have belt alignment problems unless you use a pulley spacer (by about .150").
(See Noonie's later post, #19, with the exact numbers - difference is .175")

larrywalk

The hole in the top of the pump is for a hot water bypass past the thermostat from the intake manifold. I prefer these even in engines without them because it helps to warm-up the engine evenly from both banks rather than only the passenger side bank (that's the bottom hole in the gasket on the pass side of the pump). If the bypass is not used, just use the plug to plug the top hole.

boltnut

Thanks that clears it up.


The one from napa is correct.....my old one is stamped "PH 406" and the new one is stamped "GM7".....any idea who made the old one. It's identical except for the plug on the top is a different size.

Also I'm confused about the Chevy tech article I read that says in 69 they went to long pumps. They have a window where they show two pumps and declare the long one to be 7". They go on to say these were used from 69 to 84. I have what they call a short pump then....? Mine is just under 6 inches...the old one and the new one. My car is 73. Shouldn't I have a long pump, pulleys, and brackets ?

jackson

No sbc C3 came with a LONG pump. Only short OR vette.
Like Larry said above, there are 3 pumps available for Chevy sbc.
But, sbc C3 only had 2, short or vette.

If you mix one pump with another set of brackets-pulleys you WILL have belt misalignment & many headaches. (unless you correct with PIA shims, washers etc.)

boltnut

i understand that it may not have come with the setup OE. just trying to figure out what i have and the info i am reading online seem off. seems like im confusing SBC and vette SBC i have a long pump but its the vette long pump not the chevy long pump !

Mike Ward

Very honestly, you're doing a good job of confusing yourself. If you read the info provided above, there's only ONE length of pump for C3. '71 and up had the larger diameter shaft.

Study pete74s diagram.

69 Chevy

boltnut

i agree.

noonie

Here are the specs I had for all vbelt sbc pumps

Small Block Corvette

1970 and earlier Corvette
5.625” Length Block face to hub face
.750” bearings
.625” shaft


1970 and earlier Severe Duty Corvette
5.625” Length Block face to hub face
.750” bearings
.750” shaft


1971 to 1982 Corvette
5.795” Length Block face to hub face
.750” bearings
.750” shaft

-------------------------------------------------------------

Traditional Short Pump
1968 and earlier passenger cars
1972 and earlier trucks
5.625” Length Block face to hub face
.625” shaft

Traditional Long Pump
1969 to 1986 passenger cars
1973 to 1983 trucks
6.932” Length Block face to hub face
.625” shaft

boltnut

Thanks noonie. Do you know how those numbers apply to the different bosses on the top for bypass ? Were they on severe duty pumps ? Truck pumps ?