# 400 engine ID tag



## spaz13811 (Jun 29, 2015)

HI,

I Need some help - bought a 1967 Pontiac 400 motor out of Florida for my GTO. The engine was built November 1966. It has a brass tag rivited over the engine "YS" code / unit number stamp. Anyone ever see this? The riveted tag has RC-26 and a 5 digit number on it. I can't find anyone that's seen this. I have attached a picture.Thanks for any help


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## 1968gto421 (Mar 28, 2014)

Hang in there and keep checking your post here. Some of the guys who really know their Pontiacs will chime in and give you authoritative info (like PH, Bear, OS, PJ).

I'm not really sure what it is...personally I suspect it's a tag from some engine re-builder service. 

Welcome to the Forum!!


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## spaz13811 (Jun 29, 2015)

Thanks - i'm thinking engine builder too. I just dropped it off at my machine shop, so i'll see if it's had anything done to it in the past.


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## PontiacJim (Dec 29, 2012)

Never heard of such a thing, nor read anything in all the documents I have. I suspect, like others, it was someone's way of inventorying the block or engine, or possibly used to maintain a warranty, ie "RB = Rebuilt + the inventory serial number", and had to remain on the engine for ID/Warranty claims. Don't think the factory would have ever tagged a block like that.


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## spaz13811 (Jun 29, 2015)

Thanks for the input.


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## NFDMedic (May 27, 2016)

It could be a factory rebuild or most likely a third party engine rebuilder


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## BearGFR (Aug 25, 2008)

That's a new one on me as well.

"Back in the day", there were all sorts of one-off's that happened at the factory so it's not likely anyone will ever know them all. Whether yours is one of those, or something that was done long after, such as by a rebuilder, I don't know how to tell.

Bear


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## Brandons70goat (Aug 22, 2016)

I just bought a 1970 gto with this same rage but next to the timing cover, different numbers and no letters, did yours have numbers under the bass tag, also can anyone help me decode this engine by the provided numbers


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## Pinion head (Jan 3, 2015)

[/QUOTE=Brandons70goat;747441]I just bought a 1970 gto with this same rage but next to the timing cover, different numbers and no letters, did yours have numbers under the bass tag, also can anyone help me decode this engine by the provided numbers[/QUOTE]

The block could be one of 3 different possibilitys. 

FIRST, & this is from being the near exclusive supplier providing select Pontiac engine castings to a well known national Pontiac engine builder for nearly a decade... When one observes the *(* in front of the assembly number, next to the two letter ID code,  this *(* points to the factory assembled engine being a '71-74 production piece. 

With that noted, the possibilitys are:
-mid to late '72 production 455, originally had 7M5 heads
-'73 400 with 4X 400 heads.
-'74 455 with 4X-1H heads ( big chamber doorstops)

The block casting date needs to be looked at, it is back by the distributor hole. it will read 
A-L, two digits, then a number.

Example: H182 would decode August 18th, 1972, and as such would be an early '73 model casting.

Another quick way to ID is carefully remove the mass rebuilder tag and look at the small string of numbers stamped in the face block along the pass side of the timing cover.

22X300001 would indicate 2 (Pontiac) 2 (production year 1972), X = Leeds KS big car plant (B series) 300001, the first Pontiac V8 out of Leeds Pontiac plant for '72 model year.

Pontiac A body plants VIN identifier A, G, P, Z began their last 6 digits with a 1, example 23P100001

Pontiac Firebird plant, Norwood began its last 6 digits of the VIN sequence with a 5, at least from '72 through '76

The block casting number is located on the cast flange area coming up from the oil filter boss. Look behind passenger head area. Real easy to spot if factory non AC car, or if AC box has been removed.

-'71-early '75 production 400 block was cast 481988
- mid '71-74 production 455 block was cast 485428


The above ought to get you there in ID'ing what the block is. W/o disassembly will be hard to tell what the overbore was. .030 and .040 is typical, though one local rebuilder was even casting their own 350 Chevy pistons during the '80's, & I have not disassembled examples of Pontiac engines out of a wide variety of mass rebuilders. When pulling cores, I usually shied away from Pontiac engines with mass rebuilder tags, as I knew the blocks had been prev bored, and the crank turned. Today, it wouldn't bother me, as long as the engine had not been setting getting rained in.

Welcome to the forum!


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