# 1969 GTO engine decoding HELP!



## Majestic (Feb 27, 2011)

I have a 1972 GTO with what I'm pretty certain is a 1969 400ci engine. I want to be 100% sure and also would love to know all the details reguarding this engines original production specs. I was browsing this forum and found it very helpful but I still can't find concrete answers so I decided to join. 

If anyone can help me decode the numbers I have or help me find the remaining ones I need (on the block and heads) I would be very grateful. 

On the front passengers side of the block it shows : 60128 YC 

On one of the heads it shows: D108 
The other one shows: C298

I looked on the area under the distributor and dont see any code 

Also I cant find the spot by the #8 cylinder that has the 979**** code.

Thanks for any help you all can provide


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## QwikSilver04 (Dec 25, 2010)

The "YC" engine code was in three years of GTOs, '71, '72, and '73, so it may be possible you have the original engine in your car and that would be a 455 automatic car but you need to find that a number that says 485428, if you find that number it is a 1972 455 and if its a "979" number it is Pre-1971. Hope this helps a little. If you give me a little more info I could help more.


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## GTO JUDGE (May 14, 2005)

Majestic said:


> I have a 1972 GTO with what I'm pretty certain is a 1969 400ci engine. I want to be 100% sure and also would love to know all the details reguarding this engines original production specs. I was browsing this forum and found it very helpful but I still can't find concrete answers so I decided to join.
> 
> If anyone can help me decode the numbers I have or help me find the remaining ones I need (on the block and heads) I would be very grateful.
> 
> ...


D108= Built April 10 1968
C298= Built March 29, 1968

979 casting number is located on the back of the block passenger side behind and down from valve covers not at the top of intake.

Not sure of code at dist.


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## 68greengoat (Sep 15, 2005)

Here's the locaton for the block casting # and date code cast by the distributor.


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## Majestic (Feb 27, 2011)

QwikSilver04 said:


> The "YC" engine code was in three years of GTOs, '71, '72, and '73, so it may be possible you have the original engine in your car and that would be a 455 automatic car but you need to find that a number that says ,485428 if you find that number it is a 1972 455 and if its a "979" number it is Pre-1971. Hope this helps a little. If you give me a little more info I could help more.


I had the engine rebuilt about 10 years ago and the guy said it wasn't the original motor. I thought I remembered him saying it was a "1969 400ci H.O. RA IV" motor and on the receipt it does say that. Who knows if he just built it to RA IV specs or what. I think the heads have the D ports not O ports so who knows. I will look for the 485428 number though. Thanks a lot


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## Majestic (Feb 27, 2011)

GTO JUDGE said:


> D108= Built April 10 1968
> C298= Built March 29, 1968
> 
> 979 casting number is located on the back of the block passenger side behind and down from valve covers not at the top of intake.
> ...





68greengoat said:


> Here's the locaton for the block casting # and date code cast by the distributor.


Ok perfect. I did look in that general area but the dam air conditioning "box" housing is blocking that area. I'll take a closer look when I get back over to the car. (It is garaged in another location, not at my house)

I appreciate it a lot


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## 68greengoat (Sep 15, 2005)

Majestic said:


> I had the engine rebuilt about 10 years ago and the guy said it wasn't the original motor. I thought I remembered him saying it was a "1969 400ci H.O. RA IV" motor and on the receipt it does say that. Who knows if he just built it to RA IV specs or what. I think the heads have the D ports not O ports so who knows. I will look for the 485428 number though. Thanks a lot


If it was a '69 Ram Air IV, it would be stamped XP or WW. A '69 YC engine would have been in a b-body, Bonneville, Gran Prix etc.....


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## Majestic (Feb 27, 2011)

68greengoat said:


> If it was a '69 Ram Air IV, it would be stamped XP or WW. A '69 YC engine would have been in a b-body, Bonneville, Gran Prix etc.....


Yeah thanks.. thats good to know, even my mechanic said theres just about no chance its a RamAir IV since they were very rare. It's probably just a 1969 400 built to the original HO 366 hp specs. I know it was put on a dyno right after the build and was 375+ Horsepower at the rear wheels because of the .30 overbore and some performance parts on the motor and heads.


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## BearGFR (Aug 25, 2008)

68greengoat said:


> Here's the locaton for the block casting # and date code cast by the distributor.


:agree All decoding efforts have to begin with the date code. Until you know the model year, everything else is in question. That's because all the other codes (like the 2 character block code on the front) were used for more than one year and used in some cases for very different engines.

Your two head codes, C298 and D108 indicate the heads were cast in early 1968, March 29th for one and April 10th for the other. What code is cast into the tops of the center exhaust ports? More than likely it will be two characters: (17, 18, 14, 15, 31, 16, 62, ...)

Bear


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## Majestic (Feb 27, 2011)

BearGFR said:


> :agree All decoding efforts have to begin with the date code. Until you know the model year, everything else is in question. That's because all the other codes (like the 2 character block code on the front) were used for more than one year and used in some cases for very different engines.
> 
> Your two head codes, C298 and D108 indicate the heads were cast in early 1968, March 29th for one and April 10th for the other. What code is cast into the tops of the center exhaust ports? More than likely it will be two characters: (17, 18, 14, 15, 31, 16, 62, ...)
> 
> Bear


I did see numbers on the end exhaust ports and on the middle but they were hard to read. I will check it out and get back to ya. The 979**** code it gonna be a bitch to read because of the air conditioning box in the way and the distributor area (date code) I couldn't seem to find before. I will look again and post my results as soon as I go back to the car in my storage garage. Thanks


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## BearGFR (Aug 25, 2008)

Majestic said:


> I did see numbers on the end exhaust ports and on the middle but they were hard to read. I will check it out and get back to ya. The 979**** code it gonna be a bitch to read because of the air conditioning box in the way and the distributor area (date code) I couldn't seem to find before. I will look again and post my results as soon as I go back to the car in my storage garage. Thanks


I'm sort of holding my breath here.... usually the codes on the heads are very easy to see, being 2-3 times the size of the date codes. If you've got very small numbers, and they're on the end ports... and if those date codes are correct... there's a chance you could have some round-port 68 Ram Air II's there. Here's another thing to look for: the shape on top of the center 2 exhaust ports. If the outsides of the ports seem to slant towards each other as they get closer to the exhaust manifold, sort of in a "V" shape, they're D-ports. If however the outsides run parallel with each other, staying the same distance apart both "next to" the valve cover and "next to" the exhaust manifold, they very well could be round ports.

Bear


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