454 crank pulley question.... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**FRENCHBLUE72** · 09-01-2005, 10:29 PM

Need some help in ordering my new lower pulley for my 454 chevy in my 72.. Is there really a difference in 350 and 454 crank pulleys as long as they are for the same water pump (ie long or short??) I know there is a difference in diamater but what really is the big deal other than $$.. Any feed back would be great.. Thanks Luke..

**FRENCHBLUE72** · 09-04-2005, 10:24 AM

T.t.t. One More Time..

55454 · 09-04-2005, 10:37 AM

The hole the crank bolt goes thru is larger. PM if you need any measurements.

Tommy

**FRENCHBLUE72** · 09-04-2005, 11:04 AM

Can I use a small bock pulley ona big block or do I need to shell out the extra $$$ for the b.b. lower pulley???

JimKshortstep4x4 · 09-04-2005, 10:05 PM

Although you could bore out the small block pulley center hole to the big block size and possibly make the sb pulley work it is not recommended. I compared the sb pulley against a big block (sbc pn 3755820 BC, bbc pn 3874418 BS) and they are similar in some ways. Both pulleys are for the short water pump setup and they both had the same diameter and offset. The bolt circles are the same but the center holes are different as the bbc is much larger.

The problem difference is that the pulleys are made with pilots to insure concentricity with the harmonic balancer. If you bored a larger hole in a sb then you would lose the pilot and the pulley could run eccentric to the balancer.

I would suggest getting a bb pulley for your engine.

Jim

**FRENCHBLUE72** · 09-04-2005, 11:41 PM

Thanks jim as always you are a great wealth on knowledge..

09-01-2005, 10:29 PM	#1
FRENCHBLUE72 PROJECT 7DEUCE Join Date: Dec 2002 Location: GRANTS PASS OR Posts: 21,603	454 crank pulley question.... Need some help in ordering my new lower pulley for my 454 chevy in my 72.. Is there really a difference in 350 and 454 crank pulleys as long as they are for the same water pump (ie long or short??) I know there is a difference in diamater but what really is the big deal other than $$.. Any feed back would be great.. Thanks Luke.. __________________ GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P..

09-04-2005, 10:24 AM	#2
FRENCHBLUE72 PROJECT 7DEUCE Join Date: Dec 2002 Location: GRANTS PASS OR Posts: 21,603	T.t.t. One More Time.. __________________ GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P..

09-04-2005, 10:37 AM	#3
55454 55454 Join Date: Mar 2005 Location: Lafayette La. Posts: 340	The hole the crank bolt goes thru is larger. PM if you need any measurements. Tommy __________________ 72 Cheyenne 1956 3100 1955 210 19 year old Chihuahua (Factory Teeth)

09-04-2005, 11:04 AM	#4
FRENCHBLUE72 PROJECT 7DEUCE Join Date: Dec 2002 Location: GRANTS PASS OR Posts: 21,603	Can I use a small bock pulley ona big block or do I need to shell out the extra $$$ for the b.b. lower pulley??? __________________ GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P..

09-04-2005, 11:41 PM	#6
FRENCHBLUE72 PROJECT 7DEUCE Join Date: Dec 2002 Location: GRANTS PASS OR Posts: 21,603	Thanks jim as always you are a great wealth on knowledge.. __________________ GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P..

09-04-2005, 10:05 PM	#5
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Although you could bore out the small block pulley center hole to the big block size and possibly make the sb pulley work it is not recommended. I compared the sb pulley against a big block (sbc pn 3755820 BC, bbc pn 3874418 BS) and they are similar in some ways. Both pulleys are for the short water pump setup and they both had the same diameter and offset. The bolt circles are the same but the center holes are different as the bbc is much larger. The problem difference is that the pulleys are made with pilots to insure concentricity with the harmonic balancer. If you bored a larger hole in a sb then you would lose the pilot and the pulley could run eccentric to the balancer. I would suggest getting a bb pulley for your engine. Jim



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