Big Block Water pump swap
Thread Starter
Race Director
Joined: Apr 2011
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From: North of Toronto - Ontario
Big Block Water pump swap
So it looks like the pilot on pre-71 (or is it 70) big blocks was 5/8 and on post it was 3/4, and they might be slightly longer (conflicting info there and I haven't measured)
Is there any reason a person couldn't use a spacer/sleeve to allow a 5/8 pilot pump on a 3/4 pulley setup? Everything else seems the same
Mooser
Is there any reason a person couldn't use a spacer/sleeve to allow a 5/8 pilot pump on a 3/4 pulley setup? Everything else seems the same
Mooser
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they have short and long pumps for big blocks just like the small block
http://www.chevellestuff.com/qd/water_pumps.htm
http://www.chevellestuff.com/qd/water_pumps.htm
Thread Starter
Race Director
Joined: Apr 2011
Posts: 11,183
Likes: 3,335
From: North of Toronto - Ontario
Thread Starter
Race Director
Joined: Apr 2011
Posts: 11,183
Likes: 3,335
From: North of Toronto - Ontario
they have short and long pumps for big blocks just like the small block
http://www.chevellestuff.com/qd/water_pumps.htm
http://www.chevellestuff.com/qd/water_pumps.htm
But, it looks like the 70 (maybe 71) through 74 BB vettes had a 3/4 pilot while all the rest of the GM had 5/8 pilots
Everything else seems to be exactly the same, looks like I'm going to go ahead and make up an adapter for the pilot size and change the pump over the winter.
Thanks
Mooser
Thread Starter
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Joined: Apr 2011
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From: North of Toronto - Ontario
It seems like GM made 2 different short pumps, one for most cars and then one for the vettes (depending on which article I read, from 69 on or from 71 on).
The vette ones are about 3/16 longer (about 5-13/16) and have a 3/4 pilot rather than a "normal" short pump (5-3/4) and have a 5/8 pilot.
I haven't measured one myself and haven't found out for sure if this was only SB or both SB and BB so it's only info I've found on the various vette forums
Thanks
Mooser
Here's one of the links I followed
http://forums.corvetteforum.com/c3-t...ater-pump.html
Last edited by Mooser; Sep 4, 2012 at 03:37 PM. Reason: added reference info
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Thread Starter
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Joined: Apr 2011
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From: North of Toronto - Ontario
The pump (sitting on my desk now) is a 8850, 5/8 pilot
Fits all 1965-68 Big-Block Chevy passenger cars, 1966-72 trucks and 1969-70 Big-Block Corvettes. Has 3/4" ball/ball bearing.
Dimension from block surface to hub: 5-3/4".
Inlet Diameter: 1.95"
The "Proper" vette pump is 8852 3/4 pilot
Fits all 1971-74 B/B Corvettes. Comes with heavy-duty 3/4" ball/roller bearing.
Dimension from block surface to hub: 5-3/4".
Inlet Diameter: 1.95".
So the difference looks like only the pilot diameter change, which is why I tend to think the height difference I mention above for the short pump is only for small blocks.
If anyone has a factory BB waterpump off a 71-74 off and can measure the 5-3/4 hieght, I'd like to know for sure. (mine is on the car with the fan etc so I won't know until this winter
Mooser
Fits all 1965-68 Big-Block Chevy passenger cars, 1966-72 trucks and 1969-70 Big-Block Corvettes. Has 3/4" ball/ball bearing.
Dimension from block surface to hub: 5-3/4".
Inlet Diameter: 1.95"
The "Proper" vette pump is 8852 3/4 pilot
Fits all 1971-74 B/B Corvettes. Comes with heavy-duty 3/4" ball/roller bearing.
Dimension from block surface to hub: 5-3/4".
Inlet Diameter: 1.95".
So the difference looks like only the pilot diameter change, which is why I tend to think the height difference I mention above for the short pump is only for small blocks.
If anyone has a factory BB waterpump off a 71-74 off and can measure the 5-3/4 hieght, I'd like to know for sure. (mine is on the car with the fan etc so I won't know until this winter
Mooser