Figuring out displacement on a mystery Olds motor

Steve Bakken

Steve Bakken

Not-quite-so-new-guy
Feb 20, 2015
45
9
8
#1
My son is looking to swap the 260 out of his 78 Calais for something bigger. A hardcore Pontiac friend of mine just bought a '74 Ventura with an Olds motor in it that he wants gone. The seller told him it was a 350. I know in '75 they started putting 260's in them, but this is definitely a '74 and they only used Pontiac 350's that year. So....... anyone know for sure how to determine what size it Is? And yes it is definitely Olds and not Pontiac.
 
Steve Bakken

Steve Bakken

Not-quite-so-new-guy
Feb 20, 2015
45
9
8
#3
You can tell by the casting number between the water pump and China wall, next to the oil fill tube.
If I remember correctly, it's just a series of numbers that need to be decoded. It doesn't actually show the displacement, right?
 
Steve Bakken

Steve Bakken

Not-quite-so-new-guy
Feb 20, 2015
45
9
8
#4
I have this in the Cutlass forum, but i figured I'd check here, too. My son is looking to swap the 260 out of his 78 Calais for something bigger. A hardcore Pontiac friend of mine just bought a '74 Ventura with an Olds motor in it that he wants gone. The seller told him it was a 350. I know in '75 they started putting 260's in them, but this is definitely a '74 and they only used Pontiac 350's that year. So....... anyone know for sure how to determine what size it Is? And yes it is definitely Olds and not Pontiac.
 
High Roller

High Roller

Greasemonkey
Aug 25, 2009
200
9
18
Cowtown USA, MN
#5
does it have the typical oil filler tube? if so what are the block casting # on block next to the filler tube? what # is on cylinder heads next to the #1 spark plug?
 
1bad79

1bad79

G-Body Guru
Dec 3, 2011
643
245
43
Allendale mi
#6
If I remember correctly, it's just a series of numbers that need to be decoded. It doesn't actually show the displacement, right?[/QUO
It’s a casting number snap a pic and post it we can tell you what it is snap a pic of the left front head there’s going to be a number there if it’s a sbo like a 5,6,7,7a,8 and so
 
Steve Bakken

Steve Bakken

Not-quite-so-new-guy
Feb 20, 2015
45
9
8
#7
Yes it has the typical oil fill tube. Not sure about the castings. The car is at his place yet. Won't be back over there til tomorrow eve. Trying to get my ducks all in a row before going back over there. Don't wanna go through all the hassle of trailoring it home tomorrow if it just has another 260 in it. The other no.s are just part #'s that will need to be deciphered, correct?
 
Steve Bakken

Steve Bakken

Not-quite-so-new-guy
Feb 20, 2015
45
9
8
#8
Will do
 
High Roller

High Roller

Greasemonkey
Aug 25, 2009
200
9
18
Cowtown USA, MN
#9
olds-casting-jpg.90123
olds-head-png.90126
 

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