mahoneybags21

how can i tell if the cars got the 350 or the 455?

mahoneybags21

and is the 1970 350 a big block or only the 455 was a big block

citcapp

Here's a couple of ways (others will chime in with more)

Big Block 425 and 455

425 painted red ,455 painted blue, 350 painted gold

letter designation above the number one cylinder A or B or C or D or E or F or G or Ga etc.

number designation above the number one cylinder 5 or 7 etc

Thats for starters

jensenracing77

the 350 is a small block. the fastest way to tell a small from a big is to measure the intake manifold. the big block is 14 inches wide and the small block is 12 inches wide. small blocks are 260 330 350 and 403. the big block is 400 425 and 455.

joe_padavano

Well, paint and cylinder heads can be changed. The only foolproof (and very easy) way to tell is to look at the block casting number. This is located on the small shelf above the water pump, where the oil fill tube goes into the block. Compare that number to these:

http://www.oldsmobilewiki.com/index.php/Category:Blocks

Also be aware that conventional terminology with Olds motors uses small block to refer to the short deck motors and big block to refer to the tall deck motors. Small blocks came in 260, 307, 330, 350, and 403 cu in displacements (including 260 and 350 diesel motors). The big blocks came in 400 (long and short stroke), 425, and 455 cu in displacements.

jensenracing77

thanks joe, i forgot the 307. oops

mahoneybags21

im goin to look at a 1970 delta 88 and the guy says it has the big block engine so the best way is too look at the casting number?

mahoneybags21

or does the vin number tell if the 455 would be in it?

marcar1993

Look next to the oil fill tube, if the # is "396021" then it is a 455.
This is where it will be (this is a torn down 68-76 350, location will be the same, also this is the casting # if it's a 350.)
100_3521.jpg

joe_padavano

The engine code was not included in the VIN before the 1972 model year, so no.

mahoneybags21

kk the pic helped alot thanks

serta1

I have the exact same casting number on my engine. 395558-2. Is there any way to narrow it down any more?

joe_padavano

Resurrecting a SEVEN year old thread...

Narrow what down, exactly? That casting is a 350 Olds from 1968-1976. The VIN derivative stamp will tell you the model year of the block. The head casting numbers will tell you the year of the heads. More than that requires disassembly to check specific parts.

serta1

Sorry I did not check the date of the postings. I just did a search on the site. The heads have a large number 7 on them by number one plug. I believe that means 70 or 71. Non hardened valves. Thank you for the information.

joe_padavano

Not sure where you searched, but No. 7 heads were used in the 1971 model year only and the DO have induction hardened valve seats, as to all Olds heads from the 1971 model year forward.

serta1

I looked on one of the Olds sites. It said that 7A were hardened but of course it could have been incorrect. Thank you for the information.

oldsmobiledave

Drive the car. If your fillings come loose on acceleration that is a 350. if your fillings pull out of their teeth then you have a 455. Simple.

joe_padavano

FYI, starting with the 1971 model year, every Olds engine was required by federal law to be compatible with then-new low-lead gasoline (and shortly thereafter, no-lead). That required hardened seats and lowered CR. Keep in mind that the hardened seats on factory Olds heads are simply an induction hardening of the cast iron that only goes a few thousandths of an inch deep. These heads did not use press-in seats.

There's a lot of incorrect info on-line. Those of us who were alive then remember it clearly.

rocketraider

Oh lord. That puts it as succinctly as I've ever heard it!