862 heads!
#1
862 heads!
So my friend gave me a pair of 862 heads for free! I'm planning on sending them to Texas speed for the port and valve job. I have a 1999 Trans Am ls1 A4, slp lid, chris1313 ram air, mild cam (218/227 .600/.600 valve lift 112+2 LSA), LS1 intake, 1 3/4 long tubes contacted to a 3" y pipe. Car put down 376rwhp. What would I expect to see when I put these 862 head on?
#2
These will raise your compression ratio, so a slight power gain will be expected from that alone. With the porting job and the possibility for slightly larger valves, they will knock your 853's or 241's out of the park! You'll want to ensure to install valve springs that can handle the .600 lift from your cam.
Last edited by Treyvs; 01-14-2018 at 07:28 AM.
#5
TECH Senior Member
Kinda makes a guy wonder if the quest for 243/799's is worth it? Especially when once ported, the truck heads do nearly as well! And by nearly I mean close enough!
#6
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I remember TSP saying their stage 2.5 LS6 heads were worth about 8-10 hp over their stage 2.5 5.3 heads. Now that was at peak power as well. The PRC 5.3 head might have a 8-10 hp advantage down low and midrange. Either way the heads are very close when done by the same company to keep it a fair comparison
#7
TECH Senior Member
The CNC program likely removes a bit more material from the truck heads to make them "more equal" to the LS6 head. As said, there are still some differences, but not enough to turn down a nice CHEEEP set of truck heads! lol
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#8
I like what im hearing I got the heads completely free. And I already have PAC racing 1218 valve springs in my current heads on the car so I'll just swap them over so the 5.3 heads when I get them back.
#9
TECH Senior Member
Free is SO good! lol Lets you justify putting money into them to get their full potential.
I'm assuming they're getting the Stage 2.5 porting job. This way you'll have nice-size valves and pretty decent ports. You are well on your way, my friend!
I'm assuming they're getting the Stage 2.5 porting job. This way you'll have nice-size valves and pretty decent ports. You are well on your way, my friend!
#10
Yeah theyll be getting the stage 2.5. Just a question might sound like a dumb question but me putting this on my car will it change the push rod length?
#11
TECH Senior Member
That is a GOOD question! If the heads are milled, you should measure for pushrod length as the vertical height is changed. The top of the head will be closer to the deck, to put it simply. When building an engine it is just good sense to measure anyway. Head gasket thickness could be different, etc.
#13
That is a GOOD question! If the heads are milled, you should measure for pushrod length as the vertical height is changed. The top of the head will be closer to the deck, to put it simply. When building an engine it is just good sense to measure anyway. Head gasket thickness could be different, etc.
Right now I have stock push rods right now and planned on changing them with the heads
#14
TECH Senior Member
#16
Also just wanted to know it looks like the head itself has some scratches on it not really that deep but wanted to know if they'll still be okay. Can also see the one exhaust valve doesn't look the best but I'll be changing valves.
#17
TECH Senior Member
On the pushrods, if once you check the length and you need the same length as the present ones, check them for straightness. If ALL are PERFECTLY straight, you might get away with using them again. Your call. I think I would get new, stronger ones.
#18
If they use the same size as stock ones then I'm probably gonna get hardened ones. Did you see my picture above about the scratches? Don't know if those are anything to worry about or not