I have a 1968 Chevelle SS that at some point someone put a 454 in. I am trying to figure out what 454 it is. The numbers on the engine pad at the passenger side, just below the front of the head are OA131456.
Can anyone help me out?

0-1970 A-Atlanta 131456 is the partial VIN of the car it came out of. There should be an alphnumeric stamp next to this one, and a number cast into the block.

It looks like the numbers you have posted may be the CON vin from the original car it was installed in..
0=70
A=Atlanta
131456=sequence number

Just to the left of that number should be the engine assembly date followed by the enging sufffix code.

Check the casting number! If it is a 512 block it could possible be an LS5 or LS6 block.

Check the casting number! If it is a 512 block it could possible be an LS5 or LS6 block.

We need that casting munber and suffix code!! It certainly could be but there were lot's of 454's built.

Where do i find the casting munber and suffix code?

The suffix code will be a 3 letter code at the end of the other engine stamp - should be next to the one you posted. Do you know if it has 4 or 2 bolt mains?

From Mortec:

BLOCK CASTING NUMBER
The block casting number on smallblock and big block Chevy V-8 motors is located on a ledge found at the rear of the block, most often on the driver's side. This ledge is below the deck of the block and the ledge forms the mating surface between the block and the transmission bellhousing. Some of the later model blocks have the casting number on the passenger side of this ledge. The number itself can have 6, 7 or 8 numeral digits.

I am not sure if its a 2 bolt or 4 bolt main. Am i going to be able to read the block casting number with the motor in the car?

http://www.yearone.com/updatedsinglepages/Id_info/gm_engine_id/gmidimages/endinedetail1.jpg

I got the rest of the code off the front pad of the engine
The whole pad reads

T0I27CTW 10A131456

any help with that?

T0I27CTW = 396 ci with 350hp

Like Vince said it is a 350 horse 396 (actually a 402).
T0127CTW breaks down as:
T=Tonowanda
01=January
27=27th day
CTW=402/350 Horse with a Turbo 400 transmission.

Your engine casting number by the bellhousing flange should be 3969854.
It also should have a casting date that precedes the assembly date listed above. That would look something like: K 28 9, or L 16 9, or, A 10 70, etc.

You will find the casting date by looking down between the firewall and the back of the engine, and just to the left of the distributor area. You'll probably need a flashlight to see down there.

The block casting number would be below the power brake booster area with the engine in car.

I guess you'll have to change your screenname to 1968ChevelleSS396:D

yeh i guess your right. Right after i find the guy that sold me the car and kick his ass!! Guess i should have done more research. Oh well. Its supposed to have a 396...just wish it was the correct year 396.

CTW 1970 396 350HP Chevy II HP
CTW 1970 396 375HP Chevy II SHP
CTW 1970 396 350HP Camaro HP
CTW 1970 396 350HP Chevelle HP

You should pull off the valve covers and see what the head casting numbers are...

I pulled the passenger side valve cover and this is what i found.

Toward the top front the numbers
3933148

middle top
GM4T

2/3 way back top
TRUCK

back top
D3 9

It does have Crane aluminum roller rockers though so thats good.
Also the intake is a Edelbrock 454-R Victor JR.

Did someone put 454 heads on the 396?

3933148....69-84...oval...OPEN...'69 396/265hp, 366T, 427T, 112cc chamber

Different Source...

Casting #
3933148

Years
1969

CID
366/396

Intake
2.06

Exhaust
1.72

Chamber
Open

CC
112.1

Is there anyway of telling if its a 350hp or 375hp motor?

Is there anyway of telling if its a 350hp or 375hp motor?
the ctw engine code shows a 350hp when originally made.....:yes: