455 Olds in place of 454 in 76 GMC (frame to engine mounts?)

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

OldBlueDually

Full Access Member
Joined
Jun 8, 2020
Posts
2,372
Reaction score
8,293
Location
Minnesota
First Name
Justin
Truck Year
1976 GMC
Truck Model
C30
Engine Size
455 Olds
Heck, it is worth a try! And as I always say "what could possibly go wrong" :anitoof:

When I get to this, I will let you know how it goes!
 

OldBlueDually

Full Access Member
Joined
Jun 8, 2020
Posts
2,372
Reaction score
8,293
Location
Minnesota
First Name
Justin
Truck Year
1976 GMC
Truck Model
C30
Engine Size
455 Olds
I just called the local Napa in the town I work, and they have those frame to engine mounts, $9.69 each so I am getting them both. If they fit to the mounts on the engine I will see if everything lines up properly to drop in the engine when I get to that point.
 

Craig 85

Full Access Member
Joined
Jan 25, 2017
Posts
3,889
Reaction score
4,024
Location
Nashville, TN
First Name
Craig
Truck Year
1985
Truck Model
K30 SRW
Engine Size
454/TH-400/NP205
It's been a while since I've talked Olds stuff, but one thing I do remember is with regards to Olds motors in "A" bodies. IIRC you have to use either SB frame mounts and motor mounts or BB. If you intermixed them it created either a height issue or misalignment problem. This could be related specifically to cars do to hood clearance. It shouldn't be an issue with a truck.

I love the sound of an Olds 455. Here's one of the first Olds I drove. My friend bought this in HS back in 1982. He still owns it today.

You must be registered for see images attach
 

bucket

Super Moderator
Staff member
Super Moderator
Joined
Aug 3, 2010
Posts
28,956
Reaction score
23,465
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
The Chevy engines don't use frame mounts. The rubber mount bolts right to the frame pad and then the bracket connects the rubber mount to the block. The Olds seems to have the rubbers bolted to the block and a frame stand will connect the rubber to the frame pad- much like a 60's Chevy.
 

Matt69olds

Full Access Member
Joined
Jan 8, 2018
Posts
2,338
Reaction score
3,569
Location
Central Indiana
First Name
Matt
Truck Year
81
Truck Model
GMC 1/2 ton
Engine Size
455 Olds
Olds A body’s with the 455 factory had different frame mounts and matching engine mounts. The key to getting things to fit easily and correctly is to use the the 350 engine mounts with the 455. Dimensionally, the engine blocks are identical starting with the “mighty” 260 Olds all the way to the 455. The deck height is a 1/2 taller (centerline between the crank and the cylinder head deck) which makes the engine about an 1 1/2 wider than the small block.

Next time I’m at my dads house I’ll take some detailed pics of the frame mounts. It a easy engine to work on
 

Blue Ox

Turning Diesel Fuel Into Fun
Joined
Mar 27, 2018
Posts
4,831
Reaction score
10,631
Location
LI-NY
First Name
Derek
Truck Year
MCMLXXXV
Truck Model
K20HD
Engine Size
6.2L
Right. There is no Olds "Big Block". It's a "tall block". You have to think of them as stroked small blocks. Hence the great torque numbers.

IIRC correctly the mounts on my Olds engines were blocks of rubber with studs sticking out that bolted through a hole in the chassis mount. But I never had one in a truck.
 

OldBlueDually

Full Access Member
Joined
Jun 8, 2020
Posts
2,372
Reaction score
8,293
Location
Minnesota
First Name
Justin
Truck Year
1976 GMC
Truck Model
C30
Engine Size
455 Olds
Craig 85, I WILL have one of those 68 Olds 442's some year! It is my favorite year Oldsmobile! Love the Hurst Olds pictured! Is it the 4 speed, 10 bolt posi, red plastic inner fender wells? If so only 520 some of them ever made! In '69 they were the W30. 68 was just Hurst/Olds I believe, not a W30 badge. Damned near had one, kid I worked with sold it before he moved to this area....his boss would not sell it back. I then told him why because he sold the car I describe above for a grand....and it ran & drove!

BTW I did NOT get those mounts yesterday, I decided to hold off until I know what I was getting is correct.

You guys speak of direct bolt rubber mount? If I have to I will get some mounts, be sure trans is lined up correctly, engine is set at correct angle, and level side to side and just weld in the set of mounts. IF all is correct. I don't necessarily have to bolt in mounts, I don't mind welding them right to the frame.

This 455 Olds made my 51 Ford truck (F1) haul some major you know what. The Flatty-8 is going back in that, hence why this engine is available.
 

Craig 85

Full Access Member
Joined
Jan 25, 2017
Posts
3,889
Reaction score
4,024
Location
Nashville, TN
First Name
Craig
Truck Year
1985
Truck Model
K30 SRW
Engine Size
454/TH-400/NP205
Is it the 4 speed, 10 bolt posi, red plastic inner fender wells? If so only 520 some of them ever made! In '69 they were the W30. 68 was just Hurst/Olds I believe, not a W30 badge. .

There were 515 built in '68. All were 455's with TH-400's. I believe all were W-30 cars. This one has the red fender wells and Ram-air (intakes under the bumper). This is the under hood of another H/O. I can't recall if my friend's car had A/C, but I believe it did.

You must be registered for see images attach
 

Matt69olds

Full Access Member
Joined
Jan 8, 2018
Posts
2,338
Reaction score
3,569
Location
Central Indiana
First Name
Matt
Truck Year
81
Truck Model
GMC 1/2 ton
Engine Size
455 Olds
If you have ever seen a 455 on a engine dyno, you will see they don’t have a torque curve. They have a torque plane! They start out with excellent torque, hit their torque peak, and levels off with excellent torque.
 

bucket

Super Moderator
Staff member
Super Moderator
Joined
Aug 3, 2010
Posts
28,956
Reaction score
23,465
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
@HotRodPC used to have the Olds engine mounts for a truck I think. Maybe he still has pictures.
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,008
Reaction score
8,973
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
@HotRodPC used to have the Olds engine mounts for a truck I think. Maybe he still has pictures.
Yep, I had some. Ended up selling them things on eBay. Think I got $100 for those things. I got them out of that 80 GMC that came with the 5.7 Olds Diesel and later Converted to Olds Gas 350.

Yep, Olds Big Block is just a tall small block. Most parts interchange from small block to big block. Intake won't fit of course, but the heads will interchange, water pump, some of the front engine brackets etc. Cranks could even interchange if the journals were ground down a bit to fit small block journal size.
 

OldBlueDually

Full Access Member
Joined
Jun 8, 2020
Posts
2,372
Reaction score
8,293
Location
Minnesota
First Name
Justin
Truck Year
1976 GMC
Truck Model
C30
Engine Size
455 Olds
Thanks for the info! Wish I could find some, I am not to the point of engine install yet, but I like having parts on hand so I am ready.

Kinda like a "Square Body Christmas" here the last couple days! All my engine/transmission stuff arrived, my gauge cluster arrived, carpet samples and other misc items.

If anyone has a set of those mounts just let me know, and thank you all for the help and advice!!!

Also, unrelated but why can I not post a wanted ad? Do I need to have certain permissions? Thanks!!
 

Big Chip

Full Access Member
Joined
Oct 19, 2017
Posts
4,656
Reaction score
6,728
Location
Michigan
First Name
Kevin
Truck Year
1979
Truck Model
C35
Engine Size
454
Thanks for the info! Wish I could find some, I am not to the point of engine install yet, but I like having parts on hand so I am ready.

Kinda like a "Square Body Christmas" here the last couple days! All my engine/transmission stuff arrived, my gauge cluster arrived, carpet samples and other misc items.

If anyone has a set of those mounts just let me know, and thank you all for the help and advice!!!

Also, unrelated but why can I not post a wanted ad? Do I need to have certain permissions? Thanks!!
You need 50 posts. Just keep saying welcome to everyone that shows up and it goes pretty quickly.
 

jetmech

Junior Member
Joined
May 14, 2011
Posts
10
Reaction score
7
Location
Tx
First Name
Robert
Truck Year
1986
Truck Model
1500
Engine Size
350
Yes, they are specific mounts for the olds engine. I have been on the look out for some for a couple of years now with no luck. I will fabricate some if it gets to that point in the project but would rather find the originals.
 

Battlac40

Full Access Member
Joined
May 27, 2017
Posts
191
Reaction score
97
Location
New Mexico
First Name
James
Truck Year
1981
Truck Model
K1500 Sierra Classic
Engine Size
350
Thanks for the info! Wish I could find some, I am not to the point of engine install yet, but I like having parts on hand so I am ready.

Kinda like a "Square Body Christmas" here the last couple days!!

Since your at it what about a custom engine cross-member? DIY4x4 and ORD may have a solution, even though it sounds like you are a 2wd application. Good squarebody resources.
 

Latest posts

Forum statistics

Threads
41,849
Posts
903,439
Members
33,362
Latest member
Dhatch84
Top