Flexplate for 454 w/ small torque converter bolt pattern - The 1947 - Present Chevrolet & GMC Truck Message Board Network

BigDaddyCMU · 04-04-2003, 01:10 PM

Does anyone know where I can find a flexplate for my 454, that will bolt up to a torque converter with a smaller bolt pattern? If I am not mistaken, the stock pattern is 12.5", and the smaller one is 11.75". The previous owner of the truck just drilled holes in the old flexplate. I would really rather not have to do this on my new one.

Longhorn Man · 04-04-2003, 01:18 PM

I'll asume you are putting a TH350 on your 454, if that is the case, you can install a TH400 converter (with the large bolt pattern) into the TH350 with no mods.
I would replace that flex plate though. The 454 is an axternally ballanced engine (only a 454 plate wioll do, no 396/402 plate will have the weights) but you never know if the drilled holes are upsetting the ballance job, nor do you know if they are perfectly centering the converter, which if off center even just a hair, it will damage the seal and then the tranny, and throw the ballance out of whack.

johnw67 · 04-04-2003, 07:12 PM

summit racing sells them for 454 with both bolt patterens.

crazy longhorn · 04-04-2003, 07:32 PM

most aftermarket flex plates have both patterns. IMHO, I would spend the cash for a TCI, or B&M flexplate....they are a little thicker than a stocker. longhornmail is right on , 454 only on the balance weight........crazyL

Longhorn Man · 04-04-2003, 09:18 PM

Cool, i was unaware of the daul drilled ones from the aftermarket.

04-04-2003, 01:10 PM	#1
BigDaddyCMU Registered User Join Date: Oct 2002 Location: Memphis, MI Posts: 136	Flexplate for 454 w/ small torque converter bolt pattern Does anyone know where I can find a flexplate for my 454, that will bolt up to a torque converter with a smaller bolt pattern? If I am not mistaken, the stock pattern is 12.5", and the smaller one is 11.75". The previous owner of the truck just drilled holes in the old flexplate. I would really rather not have to do this on my new one.

04-04-2003, 07:32 PM	#4
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	most aftermarket flex plates have both patterns. IMHO, I would spend the cash for a TCI, or B&M flexplate....they are a little thicker than a stocker. longhornmail is right on , 454 only on the balance weight........crazyL __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

04-04-2003, 01:18 PM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	I'll asume you are putting a TH350 on your 454, if that is the case, you can install a TH400 converter (with the large bolt pattern) into the TH350 with no mods. I would replace that flex plate though. The 454 is an axternally ballanced engine (only a 454 plate wioll do, no 396/402 plate will have the weights) but you never know if the drilled holes are upsetting the ballance job, nor do you know if they are perfectly centering the converter, which if off center even just a hair, it will damage the seal and then the tranny, and throw the ballance out of whack.

04-04-2003, 07:12 PM	#3
johnw67 Registered User Join Date: Jan 2003 Location: western nc Posts: 7	summit racing sells them for 454 with both bolt patterens.

04-04-2003, 09:18 PM	#5
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Cool, i was unaware of the daul drilled ones from the aftermarket.



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