Help identifying my engine? (aluminum)
Thread Starter
11 Second Club
iTrader: (14)
Joined: Aug 2008
Posts: 444
Likes: 0
From: Hendersonville TN
Help identifying my engine? (aluminum) Ok... to start off I'm 28, have been a mechanic off and on for the past 9 years, and have been around the block (no pun intended) when it comes to hot rods.
That being said, I'm stumped. I recently did a 6 speed swap on my car and when I pulled the flex plate off I saw a 5.3 raised casting mark with a circle drawn around it and an R drawn under that. I was told the engine was an LS1 when I bought the car and the previous owner told me the pistons were flat tops with a 5.7 marked on the head gasket.
The owner before him had a comp cam in it with ported 243 heads making somewhere in the low 4xx at the rear tires.
What do you guys think I have going on here? Can the aluminum 5.3 be bored out to accept 5.7 stuff or do I have the 4.8 pistons in there? Is there anywhere else I can check on the block to identify it?
Oh... It currently has 317 truck heads on it if that makes any difference.
That being said, I'm stumped. I recently did a 6 speed swap on my car and when I pulled the flex plate off I saw a 5.3 raised casting mark with a circle drawn around it and an R drawn under that. I was told the engine was an LS1 when I bought the car and the previous owner told me the pistons were flat tops with a 5.7 marked on the head gasket.
The owner before him had a comp cam in it with ported 243 heads making somewhere in the low 4xx at the rear tires.
What do you guys think I have going on here? Can the aluminum 5.3 be bored out to accept 5.7 stuff or do I have the 4.8 pistons in there? Is there anywhere else I can check on the block to identify it?
Oh... It currently has 317 truck heads on it if that makes any difference.
Yes, it is very common to bore the 5.3L block out to the 3.90x" bore like the LS1 guys do. They even throw 4.0" cranks in them and make them 383's quite often too! Without pulling the heads and measuring the bore of the block, it'll be hard to say if you've got 5.3L or 5.7L of displacement there!
__________________
Largest Stocking Distributor of LS-x Engines / CHECK OUT OUR NEW WEBSITE!
COMP - FAST - PACESETTER - DIAMOND RACING - EAGLE SPECIALTY PRODUCTS - CALLIES - COMETIC GASKETS
RAM CLUTCHES - MOSER ENGINEERING - KOOK'S HEADERS - ARP - GM BOLTS AND GASKETS - MSD - NGK
POWERBOND - ASP - AND MORE!
Largest Stocking Distributor of LS-x Engines / CHECK OUT OUR NEW WEBSITE!
COMP - FAST - PACESETTER - DIAMOND RACING - EAGLE SPECIALTY PRODUCTS - CALLIES - COMETIC GASKETS
RAM CLUTCHES - MOSER ENGINEERING - KOOK'S HEADERS - ARP - GM BOLTS AND GASKETS - MSD - NGK
POWERBOND - ASP - AND MORE!
Block casting numbers are behind one of the heads, IIRC. (on the block)
These sites STILL call it a "350."
12561358...325...99-up...Gen.III, used with 5.3L motors
12550592...350...97-up...crossbolted block, Gen.III, "LS1", aluminum
12559378...350...99-up...crossbolted block, Gen.III, "LS1", aluminum
12559846...350...98-up...crossbolted block, Gen.III, "LS1", aluminum
12560621...350...98-up...crossbolted block, Gen.III, "LS1", aluminum
12560626...350...99-up...crossbolted block, Gen.III, "LS1", aluminum
12560629...350...99......crossbolted block, Gen.III, "LS1", aluminum
12561168...350...01-up...crossbolted block, Gen.III, "LS1", aluminum
These sites STILL call it a "350."
12561358...325...99-up...Gen.III, used with 5.3L motors
12550592...350...97-up...crossbolted block, Gen.III, "LS1", aluminum
12559378...350...99-up...crossbolted block, Gen.III, "LS1", aluminum
12559846...350...98-up...crossbolted block, Gen.III, "LS1", aluminum
12560621...350...98-up...crossbolted block, Gen.III, "LS1", aluminum
12560626...350...99-up...crossbolted block, Gen.III, "LS1", aluminum
12560629...350...99......crossbolted block, Gen.III, "LS1", aluminum
12561168...350...01-up...crossbolted block, Gen.III, "LS1", aluminum
