Please help decoding a 5.7 LG SGI


New Member
Aug 3, 2012
67 F-Body

I'm new here and need your help for decoding a 350 V8. I'm a german guy living in munich and restoring a 67 F-Body.
The engine is reputed to be a Chevrolet Vortec ZZ4 Centerbolt 350cui.
On the left side at the back of the block ist a big "8", with "GM 5.7 LG. SGT (or SGI) under it.
On the passsnger side is the Number 10243880.
No other casting numbers were found at the moment....

My search on the web was frustrating.

Please help me.

Thank you ! Greatings from Germany.


Staff member
Oct 7, 2012
1976 Chevy Cheyenne 1500 P/U
Hello George,
I'm new at this forum, but I am hopeful I can help you a little.
In the past, one could look up engine, head, intake manifold and exhaust manifolds by the casting number and get information about their casting, from this website (
Apparently, that function has been moved and no one on this forum responds to inquiries about where that information may be!
I have found another website with some information about Small Block Chevy (SBC) casting numbers, here's the URL to that site;

Here's the home page URL;

Click the link; Chevrolet casting numbers

Now, about your engine block; the Number 10243880 is the engine block casting number, the best info I've been able to come up with on it is; "1996 - up, 350 cubic inch (5.7 liter), 2 & 4-Bolt Vortec Roller".
So, your engine is definitely a VORTEC ZZ4, with a roller cam, with any luck, yours is the 4 bolt mains, a stronger bottom end and most desirable engine for building horsepower and torque.

By my personal experience, this is a great engine to build a lot of horse power and torque, relatively inexpensively, at least on this side of the pond!
High performance parts are relatively affordable and easy to get here.
Just a $100 and a couple of hours will get approximately 10 - 12% gain in hp and 12 - 15% gain in torque, by simply replacing the valve rocker arms with a set of stamped, roller tip 1.6 ratio rockers, just as an example.
Of course, one would want to replace the adjustment nuts (they usually don't come with the roller tip rocker arms), about $1 each (requires 16), then one would want to replace the valve cover gaskets as well, about $9 - 10, so the reality would be about $125 probably plus some taxes.
But still affordable.

Using the before mentioned website, it would be beneficial to look up your heads, intake manifold and exhaust manifold by their casting numbers to see if they are proper for the engine.
Of course, if one has some spare change laying around, I'd replace the exhaust manifolds for headers (I prefer Flowtech Afterburners for best torque performance and affordable price) and replace the intake manifold for an Edelbrock AirGap intake manifold, then a Demon 750 cfm (Cubic Feet per Minute) carburetor on top of that.
Depending on the actual heads you have on your engine and the cam (of course assuming the upgrade of the roller tip rockers), you would be pushing an additional +125 horse power and +150 foot/pounds of torque!
So, for an invest of about $1250 or about $10 per horse power (less per foot/pound of torque) you would have noticeable acceleration and general performance increase.
There's a lot more to do as well, replace the cam with a higher lift, longer duration hydraulic roller cam (oh yeah, now we're getting serious! :eek: ), replace the distributor with a DUI high voltage, preset vacuum advance curve distributor . . . . and so it goes . . .

Lastly, here's a website/store that has much to offer for general repair and high performance parts for pretty much any engine;

Check out the stuff I just mentioned on their website!
I have no idea if they will ship to Germany, but all it would take to find out, is sending them an email, through their website.
Actually, they have a 'chat' function on their website, so one could find out in a few minutes on line!

Hopefully some of this helps, so, greetings from South Texas and best of luck with your project!

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