# Engine ID questions



## 66GTO7.5L (Jan 8, 2009)

I could use some help, and I know you guys are my knowledge resource. My engine is a 455 and some of the numbers are throwing me for a loop. Here is what I have so far.........

YC - 455
485428 Back Passenger side behind head - 455?
cast in valley is 55

Driver side exhaust ports (the double one center) is a 62 = 68 heads?
Cast driver side, on ridge below valve cover is B289 = Feb 15 69?

Is there another number I need to determine what year the block is?
If I have 400 heads on a 455 block, will a 455 valley pan gasket fit?

Am in process of changing the valley pan gasket, intake gasket, power steering pump, etc. Able to see some of these numbers now and they have me a little confused. Thanks for any help you can provide.


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## 05GTO (Oct 6, 2004)

66GTO7.5L said:


> YC - 455
> 485428 Back Passenger side behind head - 455?
> cast in valley is 55
> 
> ...


The letter code YC was used in 1973 on the 455 and in 1974 on the 350, the casting number 485428 was the 455 casting number for 71, 72, 73 and 74.

The 455 letter codes for 1974 were; 

1974 W8 455 290 4 
1974 Y8 455 290 4 
1974 AU 455 215/250 4 
1974 YR 455 215/250 4 
1974 YU 455 215/250 4 
1974 YW 455 215/250 4 
1974 YX 455 215/250 4 
1974 YY 455 215/250 4 
1974 ZU 455 215/250 4 
1974 ZW 455 215/250 4 
1974 ZX 455 215/250 4 
1974 A4 455 215/250 4 
1974 Y4 455 215/250 4 
1974 Y6 455 215/250 4 
1974 Y9 455 215/250 4 
1974 Z4 455 215/250 4 
1974 Z6 455 215/250 4 


The block date code should be on the pad next to the distributor.


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## 68greengoat (Sep 15, 2005)

485428 is the block casting number for a 455 for multiple years. Heads are '69. Feb 28th 1969 to be exact. Check the vin code on the front passenger side of the block next to the timing cover for the year of the block. Ex. 23X123456. The second digit "3" is the year. My block is a YC 455 from '73. YC 455 blocks with a casting number of 485428 were used in '71, '72 and '73. They used YC 455 blocks in '70 also, but with a different casting number.


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## 66GTO7.5L (Jan 8, 2009)

Thanks 05GTO - I've been doing a little more digging, and have found some good info at the spotts performance website. The head casting number 62 is for the 68/69 400. The Head cast date-code seems to confirm as a 1969 400 head...B289, D port. Time for more digging. Thanks again


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## 66GTO7.5L (Jan 8, 2009)

Thanks 68greengoat. Beside the timing cover....I looked there and didn't see anything. I will try and look a little harder. May have just missed that. At least then I would know the exact 455 block year which is what I need.

Compression calculator, however accurate, at spotts performance shows 11.25:1 comp. Engine components indicate 450hp...heck, may be more. Gotta hit a dyno around Super Chevy Show time in Commerce.


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## 68greengoat (Sep 15, 2005)

It's really difficult to see. You need a flashlight and the proper angle to look at it. Heavy paint can sometimes fill in the numbers. The radiator hose gets in the way too. Like 05GTO said, you also can find the block date code by the distributor.


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## 66GTO7.5L (Jan 8, 2009)

Behind distributor is also D1528D N. Does that mean April 15 1972 and the 8D and N are disregarded? (Regarding production date)


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## 68greengoat (Sep 15, 2005)

It's my understanding the date code should be like the other date codes D223. Maybe 05 can decipher that number you posted. The code should be on the drivers side of the distributor and slightly back.


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## 66GTO7.5L (Jan 8, 2009)

This number set was pretty much center behind the distributor. Too bad everything isn't 'text book'.


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## 68greengoat (Sep 15, 2005)

On mine, between the distributor and plug(which is used for a mechanical oil gauge) was the number 73 which was upside down(maybe you have something similar). I took that to mean 1973 and verified it against the block vin. Once I located where the vin code was by the timing cover, I used steel wool to clean up the numbers. Made it much easier to see. Some of these codes are a bear to find/see.


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## 66GTO7.5L (Jan 8, 2009)

I'll have to check that out tomorrow. I will also verify the D152 is driver side behind distributor and the 8D and N are over more to the Dist. hole on either side. I don't remember any large 73/72 or other numbers to the side of the dist. hole but will check that out too. Thanks for your help and I'll post whatever I find out. Spotts performance.com website shows a pic of the numbers behind the dist., so that's what I'll check for.


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## 05GTO (Oct 6, 2004)

The 8 is not used for IDing the engine, the D & N should have an arrow which point to one to indicate whether the block was cast during the day shift or night shift. Here is a picture of a 68/69 0071 400 block which also has the 8.


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## 66GTO7.5L (Jan 8, 2009)

Thanks for the info. I got the info together, spoke with a rep at Butler Performance, and got verifications as well as some parts I needed. Put the blower motor back on so had to drop from 4 inch valve covers to actual Pontiac chrome covers; got a new valley pan gasket; and got a little setup to relieve the increased pressure that's been spitting oil out of my valve cover breathers. Would like to pick up the Moroso Evac System, but a little rich for me at this particular time...$700 +/-. 

05GTO - I didn't see an arrow regarding what shift. I'll get a brighter light and see what I come up with.


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## 05GTO (Oct 6, 2004)

66GTO7.5L said:


> 05GTO - I didn't see an arrow regarding what shift. I'll get a brighter light and see what I come up with.


It is actually a triangle and I've seen blocks without it being used and only having the D & N cast in the block.


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## xcmac26 (Dec 1, 2008)

I'm about to Hijack this thread, but I've got a similar question. Finally got all the code off my block, buried in grime and paint, but it's a YD code translating to a 66 389 with a 2 barrel carb producing 290 HP. Just curious if anyone can dive into a few details about this motor a bit further than the info I provided. Guess I'm looking for which car model it came from and if you've got any handy links to the 4 barrel carb or better yet 3-2 barrel setup. Basically I thought I had all kinds of information stacked up about the 350 and I've been researching the wrong motor:willy:


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## 66GTO7.5L (Jan 8, 2009)

I looked at wwwPontiacpower.org site and saw YD listed for the 389 as well as the 400 and 455 blocks. Check out the spots on your block and heads for date codes like just below the valve cover on the driver side, back-left and the date code for the block like 05GTO shows in the picture above. Then you will know which engine it really is you have. Lot of great information and those able to share it. Good luck.


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