I Picked up a a Set of LS1 Heads at a Swap meet. The Down side the guy didn't have the Spec's, So the Price was Good. This is what the Guy told me

" I Sold my 2000 WS6 Trans Am for an Numbers/Project 73 Trans Am. I got the Heads from a friend(Friend was upgrading heads & Cam), I Sent them out had them Freshed up and check out. But Sold Car be for I could put them on. They where from SLP, But Patriot Perfomance at that time was making them for SLP. And I have lost the Matching Cam"

And Handed me 2 computer print outs:
one from SLP site Dated 9/15/2004 showing these heads on Clearance from SLP's site. Reg $1,949 Now $1,599. But No Spec's Can also see SLP Copyright date of 2004 on print out

2nd print out, Patriot Performance LS1 5.7L Stage 1 heads with Price, Dated Early April 2007 showed as Price comparison. As claim the SLP heads where Done by Patriot at the time when these heads where made

The heads are #853 Casting

Stamped on end of one is
CNC
2286
SLP 001 D

And Other
CNC
2286
SLP 001 P

I would like to track down the Spec's of these be for I have them Checked out and flowed to help in my search for a cam.
Also I'm looking for a creditable shop to check and flow these heads in the area of Kenosha, Wis or St Charles, ILL Thanks

 

853s are old LS1 castings. They are probably very mildly ported and probably aren't comparable to anything that's out today for the LS1 power-wise.

 

853 = paperweight

 

Times in sig with ported stock LS1 heads. Pretty fast paperweights, huh.

 

Why when there is an exception to the rule it always pops up when I open my mouth?

 

Not bad for paperweights.
But really. how much did u have your heads ported? I haven't looked much into the heads this week since i'm back to working. But they gotta be a newer casting than the stock 98 heads
There was/is 2 or more different types of ls1 stock heads Right? didn't the valve covers change in like 1999?

AL - Mind sharing what ball park of a cam your running?

 

I'm running an 853 on one side and a 241 on the other but they both were ported on the same CNC machine/program. They only have stock sized valves with dual springs and I have never flowed them but they work.
97-98 Vettes and 98 f-bodies are the only ones with the 856 perimeter valve covers.
Cam is a custom grind 228-236 .614-.607 (with 1.75 rockers) with a 114 LSA ground 2 degrees advanced.

 

The casting isn't going to matter when the heads are ported. My old Stage 1 853 heads on my P1SC Procharged setup making stock boost with a 212/218 cam put down 514rwhp through an auto.