Chelsea-Vick

All right guys, I need some help. I just picked up a 5.3 that is supposed to be out of a 2006 Silverado, but I suspect it may possibly be from an '07. Anyway, I'm having a hard time figuring out exactly which LS it is.

Here is what I have:

-5.3 iron block, 40k miles on everything
-799 heads w/ beehive springs
-Flat top pistons
-Stroke measures ~3.6 inches (indicating it's a 5.3 and not a 4.8)

I haven't seen anything specifying a 5.3 with flat top pistons, although I know the newer 5.3s can come with 799 heads.

I'm going to try decoding my casting numbers when I get home from work, but I figured I'd post here out of curiosity. I can't seem to find anything by searching.

Thanks in advance guys, and I apologize if this seems like a stupid question. Just trying to figure out what I have.

bobfig

i think the get iv had flattop pistons as they were used in both 4.8 and 5.3. they used the 799 heads to keep the compression up for the 5.3l to like 9.9:1 where they didn't do anything for the 4.8l to keep the compression up so it was a 8.8:1.

another thing if i remember right the timing cover is different.

sounds like you may of gotten a gen 4 5.3. imo keep the heads if possible and ether new crank with the correct reluctor wheel or get another short block.

i would probably get another short block as a few sensors were moved around so you would have to move them back with old parts.

76larkman

is the block aluminum? if so you probably have a L33 5.3 which do have 799 heads, flat top pistons. vin code B from 04-06 silverado/sierra 4x4 havent seen any in 2wd form. if this is a L33 its factory rated at 315 horsepower. back of block behind flywheel says litre size as well as behind steering altenator bracket. my 06 engine has 4.8/5.3 there on it but has dished piston by using screw driver in plug hole.

Tuskyz28

The casting number should help you decode the motor fully. Casting number should be located under the 5.3 stamp on the front facing of the block.

Chelsea-Vick

Thanks for the replies, guys. It's an iron block, so not an L33. I think what I've got is an LY5. Casting numbers reveal its an '07-09, so I'm guessing '07. This is not a replacement engine, it's for a jeep project of mine. I've already picked up a Lingenfelter box from another member here, and I have many of the parts I'll need for the DOD delete from another (blown up) LM7 I have it the garage. Cam and some other goodies are in the mail.