Author Topic: Big Block Water Pump info??? (Short)  (Read 7972 times)

kcandc

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Big Block Water Pump info??? (Short)
« on: July 04, 2006, 03:15:10 AM »
I bought a short big block water pump for my 68 396 project and would like to I.D. it.
The casting # is 336100, it may be 386100, but I'm sure it's 336100
The part number on the GM box is 3990993.
Anybody know what this is for??? Thanks, Karl

bertfam

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Re: Big Block Water Pump info??? (Short)
« Reply #1 on: July 06, 2006, 10:35:26 PM »
I believe the 3990993 number is a new number for the short BB pump. Can't help you with the 336100 number, sorry.

Ed

My68SS

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Re: Big Block Water Pump info??? (Short)
« Reply #2 on: January 27, 2007, 06:33:27 PM »
An old thread in need of an update. Seems 386100 may have been the actual number and after doing a google, looks to be mentioned in 'Chevrolet by the numbers 1970 - 1975'
My casting - 3856284 which appears correct for 68 396.
What was the original shaft diameter? Mine has a 3/4" size, should it be 5/8"?
Rob
1968 12C SS
L34/M40
12 bolt posi 3.55

Jerry@CHP

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Re: Big Block Water Pump info??? (Short)
« Reply #3 on: January 27, 2007, 08:59:47 PM »
284 is the correct WP casting number for '68,

Jerry

My68SS

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Re: Big Block Water Pump info??? (Short)
« Reply #4 on: January 29, 2007, 03:29:12 PM »
Thanks Jerry, do you know what the pump shaft diameter for 68 L34 396 is - 3/4" ?
Rob
1968 12C SS
L34/M40
12 bolt posi 3.55

Jerry@CHP

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Re: Big Block Water Pump info??? (Short)
« Reply #5 on: January 29, 2007, 03:32:44 PM »
I'll have to check one for you when I have a minute. 

Jerry

My68SS

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Re: Big Block Water Pump info??? (Short)
« Reply #6 on: February 08, 2007, 05:32:21 PM »
Just a prompt bump for Jerry or anyone on this shaft diameter detail as above
Rob
1968 12C SS
L34/M40
12 bolt posi 3.55

1968RSZ28

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Re: Big Block Water Pump info??? (Short)
« Reply #7 on: February 08, 2007, 06:24:13 PM »
Hi Rob -

   If I'm reading the drawing correctly in the book "Chevrolet by the Numbers 1965-69" the shaft diameter for water pump casting number 3856284 is .64" which is about 5/8"  (5/8" is .625" to be exact).

Paul

JohnZ

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Re: Big Block Water Pump info??? (Short)
« Reply #8 on: February 09, 2007, 04:40:26 PM »
The 284 casting was machined in two configurations. The one used on BB Corvettes from '65-'69 had the big bearing, a 3/4" diameter shaft, and a 5/8" pilot with a 3" bolt circle on the hub. Starting in '71, all Corvette water pumps went to a 3/4" pilot and a 3-1/4" bolt circle on the hub.
'69 Z/28
Fathom Green
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