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Discussion Starter #1
I dont have a deep groove pulley here and need to know what the depth difference is between a standard small block crank pulley(1/2 in.) and the deep grove pulley. Thanks
 

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These parts were sold across the counter as service parts as late as 2001 (they may still be available at GM for all I know).

3829387 Pulley, 302 thru 350 with special high horsepower (W/SP/HP) 3 5/8th inch Dia. 43/64ths shaft dia. Single groove deep 1/2 inch wide.

3770245 Pulley, Water pump, 1963-69 Corvette W/SP/HP, '67-'69 Camaro W/302 engine; 2 grove, deep groove (small hub 5/8th inch shaft) 7 1/8th inch diameter.

3720616 Reinforcement, water pump pulley (3770245 small hub 5/8th inch shaft)

To my knowledge GM never had a special deep groove BBC crankshaft pulley using the standard small diameter three groove pulley instead. These numbers are for a short water pump driven at 75% of crank speed (Note: BBC water pumps have a 3/4 inch shaft so the pulleys for SBCs need to be bored out to use them). Moroso and a host of other circle track vendors make a number of BBC V-belt pulleys which though admittedly not concours original but they do have a wow factor of their very own. Only the L-88 427 in the Corvette had deep V-pulleys, and they were uncommon back in the early seventies. You will probably have to go with aftermarket chromed steel or billet aluminum from March or Zoom.

Larger Dave
 

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Here are a bunch of deep groove pulleys.

deep groove

Pulley # 3858533 is a deep two groove crank pulley for short pump small blocks (will work for big block with short pump too) and is available from GM Parts Direct for about $25.00 + shipping.
 

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67 L-35, I dug out some matching deep and shallow small block pulleys to compare the depth. These are old genuine GM, not reproduction. The big block pulleys should be simular in depth.

3770245CC .735" front groove, .710" rear groove, short w/p top pulley, deep groove 67-68
3900434AB .540" front groove, .550" rear groove, short w/p top pulley, shallow groove 67-68

3956668CG .630" front groove, .615" rear groove, long w/p crank pulley, deep groove 69
3956666AG .470" front groove, .450" rear groove, long w/p crank pulley, shallow groove 69

3995647AP .630" single groove, long w/p top pulley, deep groove 70

Like a fool I left the only 3858533 67-68 Z-28 deep crank pulley I have at the shop so I cant measure it tonight. If you need that info I can measure it tomorrow and post that too.
 

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Last one I have,

3858533 BJ .610" front groove, .610" rear groove, short w/p, crank pulley, 67-68

This one is a GM pulley, a new one (not vintage) made in Canada.
 

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Discussion Starter #6
Thanks for the goin the extra mile Jon & Dave, thats exactly what I was lookin for.
 

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Here's one on e-pay you might wanna take a look at. 67-68 L78 deep groove water pump pulley.

3906656

Probably gonna get pretty pricey though.......
 
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