# 1964 76xw tri power



## tguggino (Aug 31, 2013)

is there really anything special about this motor in a 64 GTO?


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## Koppster (Jul 27, 2008)

Yes, read the thread linked below, especially John V.'s inputs.

64 389 engine question - PY Online Forums

In my observations finding a 64 76X or 78X in rebuildable condition is rare. Those who are restoring 64s and seeking numbers matching configurations will pay for a 78X or 76X.

Rick


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## tguggino (Aug 31, 2013)

Thanks. Is this the case even if it is not the original block from the car. Also why the xw?


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## ibarbuckle (Feb 24, 2014)

tguggino said:


> Thanks. Is this the case even if it is not the original block from the car. Also why the xw?


I believe the 64 block had an engine unit (identification) number that was different from the VIN. So "numbers matching" really isn't for the early GTOs. And the W code = 4 speed, X means both automatic and manual flywheels can be mounted.


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## geeteeohguy (Feb 2, 2008)

Numbers matching _IS_ for the early GTO's. The Engine Unit Number, listed on the factory Protect-O-Plate, I.D's the engine to the car. VIN numbers did not appear on GTO engines until the '68 model year, and were different from the EUN. Agree that the 76XW is a real rarity these days.


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## ibarbuckle (Feb 24, 2014)

Learn something new every day.

Pontiac Ident-O Plate & Protect-O Plate History Programs - Specific Codes - High Performance Pontiac Magazine


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## Roger that (Feb 6, 2010)

From my understanding the code 76 alone tells you it is a 1964 389 cid 348hp tri-power with a manual transmission. The X stamped tells you that the car was for the standard manual transmission. The standard 64 GTO came with a 3 speed manual. If you optioned for the 4 speed wide ratio that is where the W stamp came in. The code number 8 was stamped on the block if the engine was matched to the 4 speed close ratio trans which was offered later in the 64 model year. So 76XW is the optional 4 speed wide ratio 389 tri power.


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## geeteeohguy (Feb 2, 2008)

I concur with Roger that. Right on the money. The '65-up engines weren't as specifically coded as the '64's.


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## tguggino (Aug 31, 2013)

*76xw*

So should the block say 76xw or 76w if the manifest says it is a 76w


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## Roger that (Feb 6, 2010)

Pictures of 2 different 64s with XW on the block. The second picture show the W way over on the right side. These are 78s and not 76s


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## tguggino (Aug 31, 2013)

Thanks. If the phs doc says the engine is 76 and Trans is w, should the block say 76w or 76xw or could either be the original block?


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## tguggino (Aug 31, 2013)

*1964 76xw*

pic of the block


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## tguggino (Aug 31, 2013)

The PHS paperwork simply has 76 for engine and W for transmission. Would the original order form have said 76xw or just w?


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## Roger that (Feb 6, 2010)

1964 is an odd year for engine codes. Paperwork wise (passenger broadcast sheet and PHS) will just have numbers to show what kind of engine you have. 76 like your asking about is the 64 389 tri pwr with manual trans rated at 348hp. For some reason someone in the plant stamped letters on the block to make it easy to determine where that engine is destined to go such as the letter X for manual transmission cars. Later down the road another letter was stamped to show what kind of manual trans it was to be mated with on the engine. That is why you see the one picture i posted a few post back of the W being way off to the side.

65's WS tri-pwr engine codes does not tell me if the car came with a 4 speed or a 3 speed, just a manual transmission. Your 1964 76XW tells you everything about that engine.

So 76 is all you need on the block but the plant gave you some more info by the extra stampings.


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## tguggino (Aug 31, 2013)

Awesome. Great info. So a 76 xw would be an original Tri power engine for a 64. Very cool. 


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## Koppster (Jul 27, 2008)

Not necessarily, 76XW is a 389 w/a 4-speed. Read John V.'s post (#7) in the link below, he is a well known 64 aficionado:

64 389 engine question - PY Online Forums


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## tguggino (Aug 31, 2013)

Thanks for the link. Very helpful. Looks like the 76 is for tri power and x is standard 3 speed while xw is 4 speed. 


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## tguggino (Aug 31, 2013)

Last question on this topic. Is there any other way to correlate an original block with the phs paperwork? Some other code or number? Try to understand a claim of authenticity. 


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## geeteeohguy (Feb 2, 2008)

On '64-'66, no. Only the Protect-O-Plate will bear the original EUN. (Engine Unit Number). The PHS will just have the letter code, but not the EUN that came with that particular car.


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## tguggino (Aug 31, 2013)

Thanks. And where is the EUN on the block?


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## Roger that (Feb 6, 2010)

In your picture on post #12, those numbers below the 76xw code, is your EUN. Looking at you EUN numbers I would say it was a later build (June/July 64)


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## tguggino (Aug 31, 2013)

Roger that said:


> In your picture on post #12, those numbers below the 76xw code, is your EUN.






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## tguggino (Aug 31, 2013)

Perfect thanks for your help. 


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## tguggino (Aug 31, 2013)

Roger that said:


> In your picture on post #12, those numbers below the 76xw code, is your EUN. Looking at you EUN numbers I would say it was a later build (June/July 64)



Why do you say later build?


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## tguggino (Aug 31, 2013)

Looks like May from the phs. 


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## Roger that (Feb 6, 2010)

Your EUN is in the 400,000 range almost to 500,000. The 1st engine made for the 64 model year would have been 000,001. No way your engine could be an early build.


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## tguggino (Aug 31, 2013)

Got it. So is it possible this EUN would have been produced in May?


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## Roger that (Feb 6, 2010)

On the back of the block on the distributor pad will the date code for the engine. It should be very close to your cowl tag/PHS build date.


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