455 Rebuild - Block already 60 over

M

marcus mcgee

New member
Sep 29, 1997
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My luck is holding - all bad. The engine is out and it is already 60
over. We will try to get a 455 block from a local yard. What is the
best block to get and will a RWD 455 block interchange with my hardware
for the Toronado drive train?

Marcus
 
>My luck is holding - all bad. The engine is out and it is already 60
>over. We will try to get a 455 block from a local yard. What is the
>best block to get and will a RWD 455 block interchange with my hardware
>for the Toronado drive train?
>
>Marcus

If the 455 and the 403 are the same blocks except for deck hieght, why
would you worry about over boring until after you reached at least the same
bore of the 403 (4.351")? Looks to me like you've got another .165" to go
before even starting to be concerned about thin cylinder walls.

Big Block CIDs

CID Years Bore Stroke VIN Color
455 '72 - '76 4.126 4.250 U metallic Blue

Small Block CIDs

CID Years Bore Stroke VIN Color
403 '77 - '79 4.351 3.385 K metallic Blue

Plus, it'd have more displacement which adds up to more HP.

What's wrong with this observation? Anything?

********************************************************************
bdub Billy Massey
Life in th' Slow Lane bmassey
Lake Brownwood, Texas http://www.web-access.net/~bmassey/
future GMC'r http://wwp.mirabilis.com/202333
********************************************************************
 
NOT TRUE YOU CAN'T BORE THE 455 FOR 403 PISTONS.

marcus any of the 455 engines will work they all have the same bolt
patterns. Be sure that you use the oil pan and pickup from the toro engine
though.

If you can't find a block you might consider this:

X-Sender: ninex
Date: Mon, 20 Apr 1998 09:36:35 -0600
To: warner (thomas Warner)
From: Ninex Engine
Subject: Re: Price Quote Email

>This e-mail is in response to your form on www.ditell.com
>---------------------------------------------------------
>Quote_for = Engine - Long Block
>Year = 1976
>Make = GMC
>Model = motorhome
>Engine_Size = olds 455 CI (toronado engine)
>VIN = TZE166V100496
>Name = thomas Warner
>Address = 3692 Hogan road
>City = Vernon Center
>State = NY
>Zip = 13477
>Phone = 315-829-3398
>FAX = 315-829-3398
>Email = warner
>AT = on
>AC = on
>PS = on
>---------------------------------------------------------
>HERE IS YOUE ESTIMATE YOU REQUESTED YOUR ENGINE WILL BE $1138.00 and the
core deposit will be $225.00 THIS CORE NEEDS TO BE SENT TO THE FACTORY TO
BE INSPECTED BEFOR CREDIT CAN BE ISSUED. ANYTHING ELSE THAT WE CAN DO
PLEASE LET US KNOW.

THANK YOU

OFFICE MANAGER
NINEX ENGINE
>

>>My luck is holding - all bad. The engine is out and it is already 60
>>over. We will try to get a 455 block from a local yard. What is the
>>best block to get and will a RWD 455 block interchange with my hardware
>>for the Toronado drive train?
>>
>>Marcus
>
>If the 455 and the 403 are the same blocks except for deck hieght, why
>would you worry about over boring until after you reached at least the same
>bore of the 403 (4.351")? Looks to me like you've got another .165" to go
>before even starting to be concerned about thin cylinder walls.
>
>Big Block CIDs
>
>CID Years Bore Stroke VIN Color
>455 '72 - '76 4.126 4.250 U metallic Blue
>
>
>Small Block CIDs
>
>CID Years Bore Stroke VIN Color
>403 '77 - '79 4.351 3.385 K metallic Blue
>
>Plus, it'd have more displacement which adds up to more HP.
>
>What's wrong with this observation? Anything?
>
>********************************************************************
> bdub Billy Massey
>Life in th' Slow Lane bmassey
>Lake Brownwood, Texas http://www.web-access.net/~bmassey/
> future GMC'r http://wwp.mirabilis.com/202333
>********************************************************************
>
>
 
>NOT TRUE YOU CAN'T BORE THE 455 FOR 403 PISTONS.
>

WHY NOT, THOMAS?

I thought I had this 403 vs. 455 thing all figured out. But I can't find
any pistons bigger than .60" over available for the 455.
But this quote is taken from the Olds FAQ at
http://www.en.com/users/thall/olds/ofrbd.htm Rebuilding Engine
"I do believe sonic testing is necessary for .125 over bore. That's 482 CID
with stock stroke!"

Can you shed some light on my confusion?

Thanks

********************************************************************
bdub Billy Massey
Life in th' Slow Lane bmassey
Lake Brownwood, Texas http://www.web-access.net/~bmassey/
future GMC'r http://wwp.mirabilis.com/202333
********************************************************************
 
>

> >My luck is holding - all bad. The engine is out and it is already 60
> >over. We will try to get a 455 block from a local yard. What is the
> >best block to get and will a RWD 455 block interchange with my hardware
> >for the Toronado drive train?
> >
> >Marcus
>
> If the 455 and the 403 are the same blocks except for deck hieght, why
> would you worry about over boring until after you reached at least the same
> bore of the 403 (4.351")? Looks to me like you've got another .165" to go
> before even starting to be concerned about thin cylinder walls.
>
> Big Block CIDs
>
> CID Years Bore Stroke VIN Color
> 455 '72 - '76 4.126 4.250 U metallic Blue
>
> Small Block CIDs
>
> CID Years Bore Stroke VIN Color
> 403 '77 - '79 4.351 3.385 K metallic Blue
>
> Plus, it'd have more displacement which adds up to more HP.
>
> What's wrong with this observation? Anything?
*******

Bill;

These are not the same blocks by any means. The 403 block is entirely
different in size and setup. It is a SB not a BB.

Marcus
 
My remark was that you cannot bore the 455 for a 403 piston and I believe
that is true. The 403 piston diameter is 4.350" and the 455 is 4.125". You
would have to overbore the 455 .250" so the 403 pistons would fit. However
look at the chart and see the difference between the two pistons, 403's
being flat top pistons.

Two reasons:

1. Piston Dish Volumes

dish dish calc'd msr'd
CID CR dia. depth vol(cc) vol(ci) Notes
260
307
330 HC 10.25 2.42 .063 4.7 5.0
330 LC 9.0 2.5 .240 19.3 19.0
350 HC 10.5 W-31 piston (til '70??)
350 HC 10.25 14.0
350 LC 9.0 At least til '70
350 LC 8.5 2.85 .230 24.0 24.0
403 8.5
E400 FT 0 0 0
L400 LC
L400 HC
425 HC-T 10.5 2.75 .047 4.5 4.5 Tornado/Starfire piston
425 10.25 2.75 .065 6.3 7.0 Std. HC 425 piston
455 10.25 2.85 .150 15.7 15.0
455 10.0
455 9.0 3.010 .350 40.8 37.0
455 8.5 40.0
2. About 0.060" is about all that is safe to overbore a cylinder without
going to much inspection expense; and the casting may not be square enough
to support more anyway.

>>NOT TRUE YOU CAN'T BORE THE 455 FOR 403 PISTONS.
>>
>
>WHY NOT, THOMAS?
>
>I thought I had this 403 vs. 455 thing all figured out. But I can't find
>any pistons bigger than .60" over available for the 455.
>But this quote is taken from the Olds FAQ at
>http://www.en.com/users/thall/olds/ofrbd.htm Rebuilding Engine
>"I do believe sonic testing is necessary for .125 over bore. That's 482 CID
> with stock stroke!"
>
>Can you shed some light on my confusion?
>
>Thanks
>
>********************************************************************
> bdub Billy Massey
>Life in th' Slow Lane bmassey
>Lake Brownwood, Texas http://www.web-access.net/~bmassey/
> future GMC'r http://wwp.mirabilis.com/202333
>********************************************************************
>
>
 
>These are not the same blocks by any means. The 403 block is entirely
>different in size and setup. It is a SB not a BB.
>
>Marcus

Ok, I think I got it through my very thick skull now.

Here's another option. Perhaps another .015 would clean it up? Got this
reply this evening from mondello:
==============================================
"I have a .075 over 455 olds piston with a net bore 4.200."
Sincerely
Joe Mondello
==============================================

The owner of the '77 Royale called this evening to offer me $2k off the
$15k price if I'd take it "as is". He's afraid that it's slung a rod cap
or something by the way it sounds but he hasn't been able to get anyone out
to look at it yet.

I'd like to know what the estimate is for your overhaul. I think that this
455 is untouched except for general maintenance, I'll find out for sure
tomorrow.

How does that engine come out of there anyway? Does the front sheet metal
come off? Also, what about towing the coach with it's automatic
transmission? What precautions should be taken?

Good Luck on your rebuild! I'm gonna go search the GMCnet archives.

********************************************************************
bdub Billy Massey
Life in th' Slow Lane bmassey
Lake Brownwood, Texas http://www.web-access.net/~bmassey/
future GMC'r http://wwp.mirabilis.com/202333
********************************************************************
 
Hi "L" Block with a nickle content of 6. Chuck

> My luck is holding - all bad. The engine is out and it is already 60
> over. We will try to get a 455 block from a local yard. What is the
> best block to get and will a RWD 455 block interchange with my hardware
> for the Toronado drive train?
>
> Marcus
 
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