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Discussion Starter · #1 ·
I was wondering if anyone can help me identify a gm crate engine? I bought this engine two years ago that the guy claimed is a 10yr old "never been run" zz4. It has all of the carictoristics of a zz4. Aluminum angle plug heads, plastic timing chain cover, block says "hencho de Mexico" ect. But the problem I see is every ware I've read says the stamp on the block must say zz4 and mine does not. Here is the number stamped in mine on the block near the water pump in front of the right cylinder head. 1M1221-2P04. Can anyone decode this for me?
 

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Discussion Starter · #3 ·
I called my local gm dealer and the only number he could look up is the 8 digit casting number wich comes back as a zz block. The serial number I gave came back as built on dec 21st 2004. But he also said if it was a zz4 it should have that stamped at the end of it. Mine does not. Still don't know any more than I already did. Circle track engine maybe?
 

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What heads are on there? Chances are that if it has the L98 #463 heads it's probably the ZZ4. Normally "ZZ4" will be on the machine pad after the part number. It was on mine.
 

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Heads are #10088113 cast under the right valve cover. I was also told that there should be a zz4 stamped after the serial number on the machined pad but mine does not. That's why I'm questioning wether its a tru zz4 or not.
 

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What is it you want us to say? You bought a crate engine from some guy who said it was a ZZ4. You didn't check the numbers before you laid down the cash TWO years ago. Are you trying to sell it? If you're going to use it, what does it matter? You've identified the heads. You can pull the pan and see what the bottom end is. It's easy enough to measure your cam lift. What exactly is it you need us to say about your mystery engine? I'm not getting it at all.
 

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Just like to know what I'm putting in my car is all. This is my first engine install so I don't want to be telling people it's a zz4 if it isn't. Didn't think it would be that hard to decode if I had the serial number but even gm can't tell me what it is.
 

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Budz71 said:
Just like to know what I'm putting in my car is all. This is my first engine install so I don't want to be telling people it's a zz4 if it isn't. Didn't think it would be that hard to decode if I had the serial number but even gm can't tell me what it is.
How deep is the oil pan? If it has an originally-installed deep sump pan (~ 7" deep; 7-8 qt., w/a kick out on the side), and stock-style v-covers w/two breathers on the driver side, you prolly have a circle track "spec" engine used for racing where the engines are basically run as-is. Some had tamper-proof hardware, some not. Look for bolts or tags that look different in some obvious way- I do not know exactly what was done to make them tamper proof (or more like tamper evident, i.e. it'll show if you jacked w/the engine to get inside it), but something will be obvious if it's one like that. If it's not a tamper proof engine, there will be no such thing, but it also won't say "ZZ4", either.

Otherwise you may have a clone of a ZZ4 engine. I would want to look closely at the cam to see if it was a flat tappet or hydraulic roller (or solid if aftermarket/non- GMPP crate engine), and to see what the numbers on it were. With that info and finding the deck height and the piston volume, the compression can be calculated (the nominal head volume is known). Knowing the CR will tell you if the cam is compatible.
 
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