# engine id help



## eclipse668 (Jun 3, 2011)

Hi I recently got a 67 GTO and the owner I got it from was horrible to say the least. I am trying to ID the engine that is in it but can't quite narrow it down. Its a 400 ci I have saw those marking but on the front passanger side it says MCCLAIN eng enr 140 and I can also see 0365653 xs on the block but nothing raised where it should be located. Can you help me out at all? I know its not the original engine just cant narrow down what it was from.


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## Mr. P-Body (Jan 20, 2011)

In the back, next to where the distributor goes in, there's a "date code" cast into it. It's a 4-digit "tag" (looks like it was "screwed down" but is really cast in). The first digit is a letter, indicating the month (A- Jan, B- Feb, etc.). The second and third are numbers indicating the day of that month. The last digit is a number indicating the last digit of the year it was cast. "A237" in this case would mean Jan 27, '67 or '77. You can narrow it down further by mounting holes. 

Get that code and we can help. Is the "XS" stamped into the block, passenger's side, next to the timing cover? That's the "engine code". If we know what year, that code will tell us what HP, and what car it was originally installed in.

Jim


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## eclipse668 (Jun 3, 2011)

Thanks for the help so its G316. So is that July 31 66 or 76? I see the engine code is xs so does that make it a 66? Because I am not seeing a 66 come in 400ci? 

Does the motor unit number mean anything to help ID it?

Also, there is a D with a weird pointy thing then the letter N in big print right above if that helps at all.

Thanks again


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## 68greengoat (Sep 15, 2005)

Your right. A '66 XS code was a 389. They didn't make an XS block in '76. What is the block casting number that is located by the #8 cyclinder next to the firewall? See if it matches below.
Here's your XS options:
XS A-body 66 389 360 4-speed 802 3x2 *9778789 *2 GTO Ram Air 
XS A-body 67 400 360 4-speed L-67 1x4 *9786133* 2 GTO Ram Air 
XS A-body 68 400 360 4-speed L-67 1x4 *9792506* 4 GTO Ram Air 
XS A-body 69 350 265 Turbo 350 L-30 1x2 9790079 2 int seat 45 
XS A-body 79 301 150 Turbo 350 L-27 U 1x4 525934 2 
XS B-body 79 301 150 Turbo 350 L-37 U 1x4 525934 2 
XS B-body 79 301 150 Turbo 350 L-37 W 1x4 525934 2


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## 05GTO (Oct 6, 2004)

Next step would be to find the casting number (9786133) for 67, The first part of 67 the CN was located on the distributor pad with the date code (could be 6133). Mid year in 67 the casting number was moved behind the #8 cylinder. (see the pictures posted by 68greengoat)

The early 67 engines were identified with an engine unit number which is the number with the letter code on the front of the block, this number will be listed on the PHS billing history. The later 67 engines included the car's vin number on the front of the block next to the water pump.. 

The D / N indicates *D*ay shift / *N*ight shift. It is possible the engine is an early production 67 400 HO.


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## eclipse668 (Jun 3, 2011)

Thanks for all the help I am getting frustrated. Ok so the block casting number is 5??557 cant make out the other 2 numbers but from what I am seeing it's got to be a 76 then correct?

Is this not the the right xs number that I am looking at then? Its just to the left(passanger side) of the water pump.


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## 05GTO (Oct 6, 2004)

Lets narrow it down, how many bolts are used on the water pump? 8 or 11


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## eclipse668 (Jun 3, 2011)

8 on the water pump


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## 05GTO (Oct 6, 2004)

8 = 67-68 if indeed a 400,
11 = 69 and newer,

What are the raised codes on the center exhaust ports of the heads?


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## eclipse668 (Jun 3, 2011)

6x is the center numbers or are you talking about the raised D026?


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## 05GTO (Oct 6, 2004)

6X = 1975 - 1979, date code (D026=April.02,1976)

Where is the casting number? behind the #8 cylinder or on the distributor pad? Can you post a picture?


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## eclipse668 (Jun 3, 2011)

G316 is the cast number on the distributer pad. The D026 is the cast under the valve cover.

I can't get a good picture of the cast number behind the #8 because it so tight in there. I posted the passenger side pic. that has the 6x and D026.

I really appreciate the help.


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## eclipse668 (Jun 3, 2011)

5??557 is on the side of the block behind the #8

G316 is on distributer pad

6x on center exhuast

D026 under valve cover


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## 05GTO (Oct 6, 2004)

eclipse668 said:


> G316 is the cast number on the distributer pad. The D026 is the cast under the valve cover.
> 
> I can't get a good picture of the cast number behind the #8 because it so tight in there. I posted the passenger side pic. that has the 6x and D026.
> 
> I really appreciate the help.


Here are the block casting numbers for 1976, do any of these look familar, also, are there any codes next to the timing chain cover on the passenger side?

500810 = 350 
500557 = 400 
500813 = 455 

The numbers are not making sense, maybe a 76 block that may have been re-stamped with the 67 H.O. letter code. The timing chain cover / water pump may have been switched as well.


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## 05GTO (Oct 6, 2004)

We are both posting at the same time, arty:


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## eclipse668 (Jun 3, 2011)

So I am assuming 76 as well thanks for the help. The guy I got it from I think did a little to much drinking while working on it and I am paying for it now. 

How do I find what kind of car it was from from here? I think it has the wrong oil dipstick in it and want to be able to get the correct one.


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## 05GTO (Oct 6, 2004)

The engine was used in the A-body, B-body and the Firebird, is the dipstick too short or too long?


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## eclipse668 (Jun 3, 2011)

way to short


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## Mr. P-Body (Jan 20, 2011)

A "557" block with that casting date is a '77 model. Any date after July 4, would be for the following model year. Since all the heads are interchangeable, one cannot go strictly by the head casting, though if "6X", more than likely, the heads that came on the block.

Jim


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## 05GTO (Oct 6, 2004)

Mr. P-Body said:


> A "557" block with that casting date is a '77 model. Any date after July 4, would be for the following model year. Since all the heads are interchangeable, one cannot go strictly by the head casting, though if "6X", more than likely, the heads that came on the block.
> 
> Jim


:agree

Jim, What is your opinion on the xs letter code and the 8 bolt WP? 





eclipse668 said:


> way to short


Dipsticks came in 2 lenghts, A/C (long) and non-A/C (short),

Here are several from OPGI, call first to verify the correct dipstick;

http://www.opgi.com/searchpart.asp?search=yes&catmainid=&keyWord=dipstick&submit.x=43&submit.y=6

One last note on the block casting date and number, the 2nd and 3rd digit will ID the block as being a 76 (500557) or 77 (568557). If indeed the block is a 76 the date code is more than likely C316 which would be "date correct" for the heads D026.


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## ALKYGTO (Mar 29, 2010)

Jim and Randy, you guys know your Pontiacs. :cheers


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## Mr. P-Body (Jan 20, 2011)

The "XS" is a 170 HP 2-bbl. 400 in '76.

The older water pump/timing cover design was installed to be able to use all the correct pulleys with the brackets and accessories the car already had.

There's a very good database for Pontiac "codes" on "wallaceracing.com".

Jim

p.s. AlkyGTO, "that's my job!" -


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## 68greengoat (Sep 15, 2005)

Interesting. Pontiac Power doesn't show an XS for '76. They list it for '79. That's the problem, some sites may have discrepencies and/or incomplete information which leaves a guy scratching his head......


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## eclipse668 (Jun 3, 2011)

Thanks so much for the help everyone you guys know your Pontiac that is for sure! Pretty cool community you have here.:cheers


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## 05GTO (Oct 6, 2004)

Jim, Thanks for the wallace racing link, I generally use Fred Teufert's Website which only list single digit letter codes for 76 - 78 pontiac engines. I believe WR's site is the better resource. 

Thanks ALKYGTO, you also have a ton of knowledge and many members of this forum appreciate your assistance and passion for the GTO.


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