425->455

66starfire · 04-17-2007, 08:40 AM

Just wondering if anyone had done the 425 rotatin assembly into a 455? I am interested in this as it would offer better internals. Just wondering if anyone has any advice on the swap?

Eightupman · 04-17-2007, 09:41 AM

You will end up with a 425 in a different block and heads. Depending on the heads the 455 has, you may get some better power out of it. The 425 crank is forged, and much stronger.

You can purchase custom rods and do a little work to the 455 block to make a killer stroker motor out of the 425 crank from what I understand.

John

joe_padavano · 04-17-2007, 12:41 PM

As noted above, all you get is a 425 in a different block. The only reason to go through all the trouble is to get a block that uses the common 39 degree bank angle cam and 0.842" diameter lifters.

66starfire · 04-18-2007, 02:43 PM

Ok since I wasnt sure on this i have heard rumours. do the 455's have 2 different size lifters and bank angles?? I have from what the guy told me, a 1970 out of a olds 88.
but I was thinking of a performance motor for my starfire, and thought about the stronger factory 425 crank/rods.

joe_padavano · 04-18-2007, 06:41 PM

Quote:

Originally Posted by 66starfire

Ok since I wasnt sure on this i have heard rumours. do the 455's have 2 different size lifters and bank angles?? I have from what the guy told me, a 1970 out of a olds 88.
but I was thinking of a performance motor for my starfire, and thought about the stronger factory 425 crank/rods.

455s all have a 39 degree bank angle and 0.842" lifters.

425s could have come with either 39 or 45 degree bank angle and either 0.842" or 0.921" lifter diameter.

A 66 Starfire 425 SHOULD have a 45 deg bank angle and 0.842" lifters, but be sure to check.

If you do plan to swap parts between the 425 and 455, be aware that despite the common bore, the pistons are different. The 425 uses 7" rods; the longer stroke of the 455 requires 6.7" rods. The pistons have a different compression height as a result.

Kennybill · 04-19-2007, 03:48 AM

The "stroker" combo is to use a 455 crank with 425 rods and use Pontiac pistons. (I think a stock pontiac 455 piston is 0.028 thanthe stock Olds 455 bore) I think you end up around 470 cu. in. My Nephew has this combo with 0.030 pontiac 455 pistons. The rod bolts come close to hitting the cam lobes but DON"T. Great TORQUE engine. Later, Ken

66starfire · 04-19-2007, 08:39 AM

uhh i dont know where to put this or what to do. the forums wont let me see any new replies OR check my private messages. uhmm...anyone have any ideas?
i cant even see the new posts to this thread, even though i know there are some.

joe_padavano · 04-19-2007, 02:24 PM

Quote:

Originally Posted by Kennybill

The "stroker" combo is to use a 455 crank with 425 rods and use Pontiac pistons. (I think a stock pontiac 455 piston is 0.028 thanthe stock Olds 455 bore) I think you end up around 470 cu. in. My Nephew has this combo with 0.030 pontiac 455 pistons. The rod bolts come close to hitting the cam lobes but DON"T. Great TORQUE engine. Later, Ken

I must be missing something. If you're using the 455 crank, is that the stock stroke or are you having it offset ground? Is the purpose of the 7" rods and Pontiac pistons just to get longer rods? Do you really see the difference over a stock 455 stroke and rods (6.7") and stock Olds 455 pistons at 0.060" over? That gives you a 468 and there's no issue with rod bolt clearance or custom parts.

66starfire · 04-20-2007, 01:16 PM

oldsguy, yes it allows me to se my post after i post again, and all new posts.
the last post i can see before posting again is
"Ok since I wasnt sure on this i have heard rumours. do the 455's have 2"

thats the last post.

04-17-2007, 08:40 AM	#1 (permalink)
66starfire Member Join Date: Dec 2006 Posts: 61	425->455 Just wondering if anyone had done the 425 rotatin assembly into a 455? I am interested in this as it would offer better internals. Just wondering if anyone has any advice on the swap?

04-17-2007, 12:41 PM	#3 (permalink)
joe_padavano Moderator Join Date: Mar 2007 Location: Northern VA Posts: 1,535	As noted above, all you get is a 425 in a different block. The only reason to go through all the trouble is to get a block that uses the common 39 degree bank angle cam and 0.842" diameter lifters. __________________ Joe Padavano 64 Jetstar 88 Conv 66 442 L-69 Conv 68 W-30 69 H/O 69 442 70 W-30 72 442 84 Custom Cruiser 86 Caprice wagon (w/307 Olds)

04-19-2007, 03:48 AM	#6 (permalink)
Kennybill Senior Member Join Date: Aug 2005 Location: Youngstown, Ohio Posts: 196	The "stroker" combo is to use a 455 crank with 425 rods and use Pontiac pistons. (I think a stock pontiac 455 piston is 0.028 thanthe stock Olds 455 bore) I think you end up around 470 cu. in. My Nephew has this combo with 0.030 pontiac 455 pistons. The rod bolts come close to hitting the cam lobes but DON"T. Great TORQUE engine. Later, Ken __________________ A man has to know his limitations, especially with an Oldsmobile

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04-17-2007, 09:41 AM	#2 (permalink)
Eightupman Senior Member Join Date: Nov 2006 Location: Fayetteville, NC Posts: 252	You will end up with a 425 in a different block and heads. Depending on the heads the 455 has, you may get some better power out of it. The 425 crank is forged, and much stronger. You can purchase custom rods and do a little work to the 455 block to make a killer stroker motor out of the 425 crank from what I understand. John

04-18-2007, 02:43 PM	#4 (permalink)
66starfire Member Join Date: Dec 2006 Posts: 61	Ok since I wasnt sure on this i have heard rumours. do the 455's have 2 different size lifters and bank angles?? I have from what the guy told me, a 1970 out of a olds 88. but I was thinking of a performance motor for my starfire, and thought about the stronger factory 425 crank/rods.

04-19-2007, 08:39 AM	#7 (permalink)
66starfire Member Join Date: Dec 2006 Posts: 61	uhh i dont know where to put this or what to do. the forums wont let me see any new replies OR check my private messages. uhmm...anyone have any ideas? i cant even see the new posts to this thread, even though i know there are some.

04-20-2007, 01:16 PM	#9 (permalink)
66starfire Member Join Date: Dec 2006 Posts: 61	oldsguy, yes it allows me to se my post after i post again, and all new posts. the last post i can see before posting again is "Ok since I wasnt sure on this i have heard rumours. do the 455's have 2" thats the last post.