71 Water pump/pully help

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Aug 28, 2006 | 09:04 AM

HunterPayne

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From: Woodbridge VA

71 Water pump/pully help

I am having a really hard time determining the correct set up for water pump/pully/clutch setup. 350 base engine, no A/C, W/PS

I have a 3891398 water pump (rebuilt)
3890419 pulley (per assembly manual)

Did they make two different bolt patterns for the water pump? The water pump I have has a 3/4 inch hub and 2 1/8 inch cross measurement on the mounting studs. The pulley has a 5/8 inch hub and 1 3/4 inch cross measurement on the mounting studs.

Please help.

Last edited by HunterPayne; Aug 28, 2006 at 11:58 AM.

Aug 28, 2006 | 09:05 AM

Duke94

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From: Ann Arbor Michigan

What engine do you have? (Fill out your profile)

My parts book shows a 3998205 pump for a 350 and 3998214 for BB. Can't find any listing for 3891398. Pulley P/N is 3991423 for SB. It shows your 3890419 pulley as used on 69-70 SB.

Last edited by Duke94; Aug 28, 2006 at 09:16 AM.

Aug 28, 2006 | 09:13 AM

HunterPayne

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From: Woodbridge VA

Sorry, I got carried away. I have a 350 base engine, no A/C, W P/S

The assembly manual calls for the 3890419 pulley

Aug 28, 2006 | 12:55 PM

Duke94

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From: Ann Arbor Michigan

Quote:

Originally Posted by HunterPayne

Sorry, I got carried away. I have a 350 base engine, no A/C, W P/S

The assembly manual calls for the 3890419 pulley

I have the same car! Red no option convert. I'll go see what's on mine. Is yours missing these parts?

Aug 28, 2006 | 01:27 PM

jackson

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From: Unreconstructed, South Carolina

Quote:

Originally Posted by Duke94

I've had 2 71's w/L48 ... one w air ... one without. Both had 3/4" pilot & pulley hole ... don't recall the bolt pattern. It's so that sbc vettes had 5/8" pilot in 70 & back ... and 3/4" pilot beginning MY1971. Also, note that a plain jane non-vette "short " 71 sbc pump is not a vette "short" 71 pump ... 71 sbc vette pumps have a different hub-to-block dimension than other short pumps.

Last edited by jackson; Aug 28, 2006 at 01:30 PM.

Aug 28, 2006 | 01:28 PM

Duke94

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From: Ann Arbor Michigan

Just checked my 71'. It has a two groove pulley P/N 3991423 with 2 1/8" bolt centers (as near as I can measure). WP shaft is 3/4". Checked my 78' and it is exactly the same. Checked my parts book a little closer and 3991423 is correct for 71-72 (350).

Hope that helps.

Aug 28, 2006 | 01:37 PM

HunterPayne

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From: Woodbridge VA

The problem is that the 3891398 water pump has a 3/4 inch shaft but the pulley has a 5/8 inch mounting hole. I am not sure if I have the wrong water pump or pulley. The casting number for the pump is correct from the Engine Casting Numbers book, and the pulley is correct from the assembly manual. PLEASE HELP

Aug 28, 2006 | 01:55 PM

jackson

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From: Unreconstructed, South Carolina

Quote:

Originally Posted by HunterPayne

First, I suggest you may have the wrong pulley. Second, when a pump is rebuilt, builder can install either 5/8" or 3/4" shaft in the core casting ... either are direct fit into casting. Unless it was rebuilt by a specialty house ... they simply disassemble MANY pumps of all sorts ... tumble em to get rust off ... then assemble w/ new parts ... usually new shafts too. I don't have any books w/ casting/part numbers ... but I've had 2 MY1971 w/ base L48 ... both were survivors when I got em ... personally did extensive work to both. I remember chasing after shaft/pulley issues when I changed stuff.