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Discussion Starter #1
So what I thought was a ZZ4 in my '82 appears not to be. I had a valve cover off earlier to look at the rockers and looked up the identification numbers stamped into the head (12558062) which ended up being Vortec heads. This got me going down a rabbit hole and ending up taking off the front accessories to check the front engine pad. That pad ended up being a short one and read:
1M0226
9G01

Can anyone decode those numbers and tell me what I have? All I know is it's got Vortec heads now and that it has a 1 piece rear main seal.

135025


135026
 

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vortec heads use a different intake manifold than other heads, only 8 bolts going straight down not on a angle. also on the front of the head there will be wut looks like a saw tooth pattern and center bolt valve covers. hope this helps you out.
 

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Discussion Starter #4
I already know its a Vortec top end, seems to be some sort of aftermarket block made by GM but that's as far as I've gotten with it. Reaching out to a few places basically has led me to believe that there's no good way to decode it. I also tried calling GM customer service on it being that it's a GM-made block but the person on the phone didn't seem to know what a crate motor is in the first place, let alone anything about them. At some point I'll install a set of Edelbrock heads I have for it and while the top end is apart I'll be able to get more information on what exactly is inside it.
 

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mortec.com

CASTING#.....SIZE...YEAR.....NOTES
12558062........350......98..........L31 Vortec, truck, 64cc chambers, 1.94/1.5, 170cc intake port

12558060 - Vortec "L31" '96 350 complete cylinder head, cast iron, 1.94"/1.5" valves, 170cc intake runner volume, 64cc chambers, comes with springs, retainers and valves, has bracket/accessory holes, use with Vortec style intake manifolds (PN-12366573). Pressed in 3/8" rocker studs, use self aligning rocker arms (PN-12495490 1.5 stamped rocker arm kit). Straight plug location. Does not have heat riser passage. Excellant performance and flow (239cfm @ .500" lift unported) for the price. Head can be cut for 2.02"/1.6" valves and screw in studs. Use on Gen.I style blocks only. Use with cams up to .475-.480" lift. Larger cam lifts will require a different valve spring and machine work to the valve guide bosses for clearance. Casting number 10239906 or
12558062


searching these numbers found this....
1M0226
9G01

How to Decipher SBC Engine Code Serial Stamping Numbers
"The folks over at NastyZ28.com have managed to compile one of the most complete suffix code databases online currently that we could find, so if you want to dig into your small block a bit more, give them a look. "


 

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Discussion Starter #7
Well I found the casting stamp on the back of the block on the passenger side last night. It was 10243880 which came up as 350, 4 bolt, crate engines and ZZ4, roller cam, one piece rear seal. From what I can tell it was also used for L31 Vortec truck motors as well. Based off the stamp on the front I'm thinking this is a replacement L31 engine, probably a Targetmaster/Goodwrench. Its a little disappointing being that I thought it was a ZZ4 but once I tear the top end off for a heads and cam upgrade it shouldn't make too much of a difference. Its already decently powerful for what it is, at least based off the butt dyno.
 

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Well I found the casting stamp on the back of the block on the passenger side last night. It was 10243880 which came up as 350, 4 bolt, crate engines and ZZ4, roller cam, one piece rear seal. From what I can tell it was also used for L31 Vortec truck motors as well. Based off the stamp on the front I'm thinking this is a replacement L31 engine, probably a Targetmaster/Goodwrench. Its a little disappointing being that I thought it was a ZZ4 but once I tear the top end off for a heads and cam upgrade it shouldn't make too much of a difference. Its already decently powerful for what it is, at least based off the butt dyno.
10243880...350...95-00...2 or 4...Vortec truck, Gen.I crate motors and "ZZ4", roller cam, one piece rear seal

so it sounds like the same engine block as what I had in my 99 Suburban, which had about 250hp/350tq. don't think it was a 4bolt though.

 

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Discussion Starter #9
10243880...350...95-00...2 or 4...Vortec truck, Gen.I crate motors and "ZZ4", roller cam, one piece rear seal

so it sounds like the same engine block as what I had in my 99 Suburban, which had about 250hp/350tq. don't think it was a 4bolt though.

Think it'll take a bit of abuse with basic heads/cam upgrade? I'm not exactly nice to my cars but it won't ever see nitrous and probably not more than the very occasional drag strip pass. When I learned it wasn't the ZZ4 I thought it was I debated throwing a 6.0 LS into the car I've had sitting in the corner of my garage... If this engine is stout enough though I'd rather run what I have with some upgrades and keep it old school, even if it won't be as fast.
 

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Think it'll take a bit of abuse with basic heads/cam upgrade? I'm not exactly nice to my cars but it won't ever see nitrous and probably not more than the very occasional drag strip pass. When I learned it wasn't the ZZ4 I thought it was I debated throwing a 6.0 LS into the car I've had sitting in the corner of my garage... If this engine is stout enough though I'd rather run what I have with some upgrades and keep it old school, even if it won't be as fast.

 
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