# Need help identifying engine size



## gotyorgoat (Jun 19, 2011)

Just picked up a 67 lemans and the guy told me it had a 389 motor in it from a GTO. How do I verify this? Here is the only information that I could find on the block.


On the front passenger side of the block
C148340
YC

On the headcover
B082
7M5

I am looking to verify year and displacement. Thanks for the help!


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## 05GTO (Oct 6, 2004)

The head code (7M5), the head date code and the engine letter (YC) all were used on a 1972 455, the casting number for a 72 should be behind the #8 cylinder and will be 485428.

If the engine is a 389 the casting number will be located next to the distributor along with the engine date code. YC was used in 65 and 66 for the b-body (290hp 2-bbl) 389, the block casting will be 9778789.


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## gotyorgoat (Jun 19, 2011)

You know your stuff. I just crawled under to see how many freeze plugs it has (3 per) and I saw the 455 on the bottom of the block. 3 plugs tells me post 67 and the transfer lug on the passenger side of the distributer tells me it is not the 389 or 400. I think we figured it out. Not sure if that is a good thing. I'll have to do some reasearch on the 72 455.

Thanks for the help!


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## gotyorgoat (Jun 19, 2011)

Do you know if there is any way to verify what model of pontiac this came out of?

Can I refer to it as a 455 HO? Am I correct that all 455's were high outputs in 72? 

Thanks again...


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## 68greengoat (Sep 15, 2005)

It is not an HO. HOs were stamped YB or WM in '72. YC was the only non HO. A and B body, '71/'72, 455s had a block casting #485428. Along with '73 F and B bodies. You need to check the casting date by the distributor.  It's a '71 - '73. Even tho the heads are '72, they could have been attached to a different block. 455s didn't enter production until '70.


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