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Feb 13, 2015 | 08:43 AM

Tom454

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Le Mans Master

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From: Raleigh North Carolina

Water Pump question

Did GM switch to the "long style" water pump (small block) at some point after 1966? If so, which year?

Feb 13, 2015 | 11:03 AM

MelWff

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to my knowledge all corvettes up to and including C3 use the short SB pump. There are other threads on this site that go into the detail with measurements of the differences between long and short .

Feb 13, 2015 | 03:35 PM

Tom454

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Le Mans Master

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From: Raleigh North Carolina

Thanks. I need to order a later year TC cover without the tab on it so that I can use a aftermarket harmonic balancer.

This one:
https://www.paragoncorvette.com/p-34...ing-cover.aspx
or this one
https://www.paragoncorvette.com/p-35...ing-cover.aspx
should fit behind a short leg OEM water pump.

I have both of these and one tab hits the balancer and the other tab is too far away.
https://www.paragoncorvette.com/p-35...ing-cover.aspx
https://www.paragoncorvette.com/p-35...ing-cover.aspx

The aftermarket ones are too tall and hit the water pump. I'm not a fan of double/triple gasketing the water pump to clear the TC cover. Misaligns the belts.

Feb 13, 2015 | 04:41 PM

MelWff

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the paragon 6732 is too far away with an 8" balancer?

Feb 13, 2015 | 05:00 PM

Tom454

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Le Mans Master

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From: Raleigh North Carolina

Quote:

Originally Posted by MelWff

the paragon 6732 is too far away with an 8" balancer?

I'm trying to fit the Summit #161350 6.75" balancer. It's 3/4"+ away from the 6732 tab. That will make it too hard to get an accurate tune. I'd like it to be a little closer to the tab.

Feb 14, 2015 | 12:25 AM

Ibanez540r

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From: Medina Ohio

I was able to bend the tab back and forth several times and get the tack weld to seperate removing the tab from the cover with no damage. I then used a bolt on timing pointer for the appropriate size balancer.

(in my case the cover was already off and I powder coated it after, but no reason you couldn't remove it while installed and leave as is)

Feb 14, 2015 | 10:00 AM

Tom454

Thread Starter

Le Mans Master

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From: Raleigh North Carolina

Quote:

Originally Posted by Ibanez540r

Thought about doing that, but decided to keep the cover with the original 327 and cob up a new setup for the 383.

Feb 14, 2015 | 02:25 PM

pws69

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From: Eastern US XX

Quote:

Originally Posted by Tom454

Did GM switch to the "long style" water pump (small block) at some point after 1966? If so, which year?

Short-Style Pump for most 1955-72 cars & trucks (5/8" pilot shaft)
- Fits all 1955-68 S/B Chevy passenger cars, 1969-70 350 c.i.d. Corvettes and 1955-72 light duty trucks.
- Has 3/4" ball/ball bearing.
- Dimension from block surface to hub: 5-5/8".
- Inlet diameter: 1.80".

Long-Style Pump for 1969-87 V8, 90° V6 & 1973-86 truck (5/8" pilot shaft)
- Fits all 1969-87 S/B Chevy or 90° V6 passenger cars and 1973-86 light duty trucks.
- Does not fit Corvettes (use #8810 or #8812) or late-model vehicles with serpentine accessory drive belts (use #8881).
- Has heavy-duty 3/4" ball/roller bearing.
- Dimension from block surface to hub: 6-15/16".
- Inlet diameter: 1.80".

Short-Style Pump for 1971-82 Corvettes 3/4" pilot shaft)
- Fits all 1971-82 S/B Corvettes.
- Comes with heavy-duty 3/4" ball/roller bearing.
- Dimension from block surface to hub: 5-13/16".
- Inlet diameter: 1.80".

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Feb 15, 2015 | 08:08 AM

Tom454

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From: Raleigh North Carolina

Thanks for that info... I'll print it and keep it with the build sheet on my engine.

Feb 16, 2015 | 12:03 AM

#10

Barry's70LT1

Melting Slicks

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From: Halifax, Nova Scotia, Canada

Quote:

Originally Posted by Tom454

Thanks for that info... I'll print it and keep it with the build sheet on my engine.

Just a little more trivia. Not all Short-Style Pumps (1955-70 ) were created equal.
The dimensions are all the same, however there are different castings. Some pump belt pulleys do not fit all the different castings.
The pump pulley on my '70 needs a "step" in the body casting, otherwise the pulley will hit the pump casting before limiting on the pump flange.

Feb 16, 2015 | 12:35 AM

#11

doorgunner

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From: New Or-leens Loo-z-anna

Also......my rookie understanding..............LONG and SHORT represents the distance from the engine block water inlet surfaces to the rear cover on the water pumps.

The distance is shorter on the '55-'72 short pump.......

Short-Style Pump for most 1955-72 cars & trucks (5/8" pilot shaft)
- Fits all 1955-68 S/B Chevy passenger cars, 1969-70 350 c.i.d. Corvettes and 1955-72 light duty trucks.
- Has 3/4" ball/ball bearing.
- Dimension from block surface to hub: 5-5/8".
- Inlet diameter: 1.80".

The distance is is........longer......on '71-'82 short pump.......

Short-Style Pump for 1971-82 Corvettes 3/4" pilot shaft)
- Fits all 1971-82 S/B Corvettes.
- Comes with heavy-duty 3/4" ball/roller bearing.
- Dimension from block surface to hub: 5-13/16".
- Inlet diameter: 1.80".

So the short style pump has a short and a long casting/the "short casting" is 3/16" shorter than the "long casting"....which causes some water pumps to need thicker gaskets in order for the rear cover of the water pump to clear "heavy-duty" timing covers and also causes a mis-alignment on the water pump pulley.

Feb 17, 2015 | 09:57 AM

#12

pws69

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From: Eastern US XX

Quote:

..........LONG and SHORT represents the distance from the engine block water inlet surfaces to the rear cover on the water pumps.

Not correct - as it says - from the BLOCK to the FACE of the HUB that the fan bolts to.

Feb 17, 2015 | 10:24 AM

#13

Tom454

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Le Mans Master

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From: Raleigh North Carolina

Quote:

Originally Posted by pws69

Not correct - as it says - from the BLOCK to the FACE of the HUB that the fan bolts to.

And I think that would also mean no gasket in the mix. I just rebuilt a OEM pump and the directions provide measurements from the block face of the pump. IE- not the block face of the block, pump installed with gasket. Just a minor clarification.

Feb 17, 2015 | 11:30 AM

#14

doorgunner

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From: New Or-leens Loo-z-anna

Quote:

Originally Posted by pws69

Not correct - as it says - from the BLOCK to the FACE of the HUB that the fan bolts to.

Yep! You are right. That's what it says. But I'm talking only about the two versions of the short style pump (when you measure the two versions of the early pumps you will find the distance from the hub to the block is different at the length of the casting where the water flows on each side of the pump body/this different length---5 & 5/8" verses 5 & 13/16" can cause the pump rear cover to jam against the timing cover)

I always thought that the early "long pump" meant a long "nose"/shaft casting on the front of the pump housing which would cause the pulley mis-alignment also.

(Then there is the "long style" pump which is noticeably longer by approx. 1" which I am not referring to because that block-to-hub- length is so obvious)

Basically....we're talking about the same things (pump lengths) which can cause installation problems....I just stumbled upon the difference one day when laying the two versions of the short pump side-by-side because my replacement pump jammed against the timing cover, and I didn't want to stack pump gaskets together to solve the problem and then create a fan-belt problem.