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Username Post: Big block gmc        (Topic#363793)
gfm64 
Poster
Posts: 99

Reg: 09-06-16
12-29-20 11:49 AM - Post#2810961    

My grand son has a 72 GMC 1 ton dually. Some one some where dropped a big block of unknown size in it. Now he wants me to find out what it is. I'm guessing a 402 but I'm no expert. The number on the block above the water pump is cast in. number is 557752 3B any one know what that is?



 


dgstarr 
"4th Year" Silver Supporting Member
Posts: 265
dgstarr
Loc: Portland, OR
Reg: 04-16-13
12-29-20 04:47 PM - Post#2810977    
    In response to gfm64

Believe it or not: 1977-1980 Oldsmobile 350 V8

Dave



 
wagonman100 
Site Ambassador
Posts: 15361

Loc: Baltimore, MD
Reg: 11-27-04
01-02-21 09:26 AM - Post#2811190    
    In response to dgstarr

Yes, that is the casting number for the Olds 350. The Olds valve covers do not look like Chevy ones and may make you think it is a big block. A picture of the engine would help or do a search for pictures of the Olds engine and see if it looks like the one in the truck and report back.

Jay
Friends don’t let friends drive Fords.

1999 Silverado Z71 4X4 extra-cab short bed
1983 Malibu Fauxmad - tubbed
1978 El Camino Kustomized
1972 Monte Carlo
1957 210 handyman wagon
1957 Nomad sport wagon
1957 Cameo Carrier


 
DZAUTO 
Member #51
Posts: 9080

Loc: Mustang, OK, USA
Reg: 12-25-99
01-02-21 09:44 AM - Post#2811193    
    In response to wagonman100

  • wagonman100 Said:
Yes, that is the casting number for the Olds 350. The Olds valve covers do not look like Chevy ones and may make you think it is a big block. A picture of the engine would help or do a search for pictures of the Olds engine and see if it looks like the one in the truck and report back.



Unless a person specifically knows the difference between a SB and BB Olds engine, it is nearly impossible to tell (unless you know your Olds casting numbers, or, what to look for).

Unlike Chevy SB and BB engines, Olds simply raised the block decks 1in. ALL, I mean, ALL Olds SB and BB valve covers, oil pans, brackets, accessories, exhaust manifolds, heads, pulleys, water pump, etc, etc, etc are a bolt on swap between SB and BB Olds engines.
OF COURSE, since Olds BB block decks are 1in taller, that means the BB intake manifolds are wider (and accessory belts are longer ------------------BUT THE BOLT PATTERNS ARE THE SAME AS SB MANIFOLDS.
In ultra simple terms, to replace a SB Olds (ie, 350) with a BB (ie, 455), you simply unbolt the exhaust manifolds from the heads, pull the 350, drop in the 455 and bolt the exhaust manifolds to the 455. NO, it's not exactly that simple ------------------------ but DAMN close.
The SB Olds are 260, 307, 330, 350, 403. The BB Olds are 400, 425, 455. And of course, internals are completely different. But on the outside, swapping a SB/BB Olds is TOOOOOOOOOOOOO EASY!

And yep, I've done it 2-3 times.
Oh ya, and Pontiac V8s are pretty much the same way.




 
DZAUTO 
Member #51
Posts: 9080

Loc: Mustang, OK, USA
Reg: 12-25-99
01-02-21 09:48 AM - Post#2811194    
    In response to wagonman100

  • wagonman100 Said:
Yes, that is the casting number for the Olds 350. The Olds valve covers do not look like Chevy ones and may make you think it is a big block. A picture of the engine would help or do a search for pictures of the Olds engine and see if it looks like the one in the truck and report back.



Unless a person specifically knows the difference between a SB and BB Olds engine, it is nearly impossible to tell (unless you know your Olds casting numbers, or, what to look for).

Unlike Chevy SB and BB engines, Olds simply raised the block decks 1in. ALL, I mean, ALL Olds SB and BB valve covers, oil pans, brackets, accessories, exhaust manifolds, heads, pulleys, water pump, etc, etc, etc are a bolt on swap between SB and BB Olds engines.
OF COURSE, since Olds BB block decks are 1in taller, that means the BB intake manifolds are wider (and accessory belts are longer ------------------BUT THE BOLT PATTERNS ARE THE SAME AS SB MANIFOLDS.
In ultra simple terms, to replace a SB Olds (ie, 350) with a BB (ie, 455), you simply unbolt the exhaust manifolds from the heads, pull the 350, drop in the 455 and bolt the exhaust manifolds to the 455. NO, it's not exactly that simple ------------------------ but DAMN close.
The SB Olds are 260, 307, 330, 350, 403. The BB Olds are 400, 425, 455. And of course, internals are completely different. But on the outside, swapping a SB/BB Olds is TOOOOOOOOOOOOO EASY!

And yep, I've done it 2-3 times.
Oh ya, and Pontiac V8s are pretty much the same way.


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rrausch 
"16th Year" Silver Supporting Member
Posts: 14674
rrausch
Loc: L.A, Cal. & St. Louis...
Reg: 04-07-03
01-02-21 11:29 AM - Post#2811201    
    In response to DZAUTO

I have a buddy who has used the BPO 455 engines in several hot rods. He also has a '73 Buick Riveria with the 455. I've driven that Riv, and MAN ALIVE that thing burns up the road.

1953 210 Convertible, 261 with dual Carter YF 966S carbs, P.S., Remote Bendix P.B. Booster... shade-tree restoration about done.




 
DZAUTO 
Member #51
Posts: 9080

Loc: Mustang, OK, USA
Reg: 12-25-99
01-02-21 11:53 AM - Post#2811203    
    In response to rrausch

  • rrausch Said:
I have a buddy who has used the BPO 455 engines in several hot rods. He also has a '73 Buick Riveria with the 455. I've driven that Riv, and MAN ALIVE that thing burns up the road.



The Olds 455 is a long stroke (stroke is bigger than bore!!!), long rod engine. They are not famous for top end rpm, but the low-mid torque is awesome. On the street, a well tuned W30 Olds will embarass an LS6 Chevelle. The 455 above that I built for the Cutlass is bored .060 and built to W30 specs. With the 3.27 1st gear in the Richmond 5sp and the 2.41 rear, it is a street killer and Interstate cruiser. The factory air cond is cold and still on R12. The cruise works just like it did when I bought it new. Very plain jane on the outside.



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gfm64 
Poster
Posts: 99

Reg: 09-06-16
06-19-21 09:54 AM - Post#2821799    
    In response to dgstarr

Well! the intake looks a lot larger than a 350 the distributor is on the back but from the pictures Ive seen you may be right.



 
gfm64 
Poster
Posts: 99

Reg: 09-06-16
06-19-21 09:56 AM - Post#2821800    
    In response to DZAUTO

Nice car . The engine matches yours even down to the exhaust manifold.



 


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