Rear end choice

GLMP1968 · August 7th, 2004, 08:52 AM

I have rebuilt a 1970 455 with Forged Speedpro pistons, comp cam 490/490 lift, new comp cam springs, mildly or portmatched heads to my Torker 455 intake, and the whole assembly was balanced. Do you think that the 355 posi I have in is the correct gearing or should I go steeper? It is not a daily driver, just a weekend warrior. I have had people tell me to go as steep as 390 or 410 gears. Do you thnk that is too high of RPMs on my big block?

Oldsguy · August 9th, 2004, 07:26 AM

I wish I could answer directly but I can't, I recommend you ask the guys at Realoldspower.com, they have a "race" forum where you could get a very good answer probably on the first day. Good luck.

monzaz · September 5th, 2007, 03:32 PM

Well I talk to alot of Buick guys and they have the 455 low end torque monster rears too. they will not go over a 3.90 for even a serious race car. I would say spend your money on a set of slicks and have some fun with all that torque. Alot of the Buick guys are even going to 3.08 gears because with all the torque and with slick you really do not loose that much ET from a mid 3 series ratio like 3.42 3.64 ratio. Just some info for you. Jim

J D Race.com

August 9th, 2004, 07:26 AM	#2 (permalink)
Oldsguy Hot Rodder at heart Administrator Join Date: May 2004 Location: Lees Summit MO Posts: 5,360	I wish I could answer directly but I can't, I recommend you ask the guys at Realoldspower.com, they have a "race" forum where you could get a very good answer probably on the first day. Good luck. __________________ Dan '77 Cutlass Supreme '46 2 door "The rocket 455.....it's a sledgehammer approach to a thumbtack world" LuxBlue of HAMB.

September 5th, 2007, 03:32 PM	#3 (permalink)
monzaz Registered User Join Date: Jul 2006 Location: Richfield, Oh Posts: 209	questions differential ratio Well I talk to alot of Buick guys and they have the 455 low end torque monster rears too. they will not go over a 3.90 for even a serious race car. I would say spend your money on a set of slicks and have some fun with all that torque. Alot of the Buick guys are even going to 3.08 gears because with all the torque and with slick you really do not loose that much ET from a mid 3 series ratio like 3.42 3.64 ratio. Just some info for you. Jim J D Race.com

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August 7th, 2004, 08:52 AM	#1 (permalink)
GLMP1968 Junior Member Join Date: Jul 2004 Location: Lansing,mi Posts: 1	I have rebuilt a 1970 455 with Forged Speedpro pistons, comp cam 490/490 lift, new comp cam springs, mildly or portmatched heads to my Torker 455 intake, and the whole assembly was balanced. Do you think that the 355 posi I have in is the correct gearing or should I go steeper? It is not a daily driver, just a weekend warrior. I have had people tell me to go as steep as 390 or 410 gears. Do you thnk that is too high of RPMs on my big block?