Help an Aussie 6l cam l92 heads
Thread Starter
Staging Lane
Joined: Nov 2009
Posts: 57
Likes: 0
From: Australia
Help an Aussie 6l cam l92 heads Hi all HELP!!!!!
I own a G8 ute with a 6l or L76 for you guys i had a 224/244 crane cam with all the good bolt ons 1 7/8 headers 3" exhaust FAST 102 and N/W 102 throttle body made good power 317rwkw's(sorry were in kw's not hp) in a M6 but decide go further. New comp lsr cam 239/247 114lsa with ported heads(flow 370cfm intake) milled 40 thou and the LSXR ported aswell. Yes big cam but this is a weekender with some trackwork fun and my daily has a 232/234 comp in a 5.7.
We'll the 239/247 .624 .624wouldn't fit due to PTV issues not even close i've now fitted a second hand 227/239comp lsr 112lsa .617 .624 and even with 80thou flycuts still won't fit i only have 10 thou on intake and 40 thou on exhaust. Looks like the heads have been milled to much only 60cc chambers
Any ideas on a lower lift decent sized cam that will fit, i'm running comp lsr double springs with there retainers.
Cheers for any advice
I own a G8 ute with a 6l or L76 for you guys i had a 224/244 crane cam with all the good bolt ons 1 7/8 headers 3" exhaust FAST 102 and N/W 102 throttle body made good power 317rwkw's(sorry were in kw's not hp) in a M6 but decide go further. New comp lsr cam 239/247 114lsa with ported heads(flow 370cfm intake) milled 40 thou and the LSXR ported aswell. Yes big cam but this is a weekender with some trackwork fun and my daily has a 232/234 comp in a 5.7.
We'll the 239/247 .624 .624wouldn't fit due to PTV issues not even close i've now fitted a second hand 227/239comp lsr 112lsa .617 .624 and even with 80thou flycuts still won't fit i only have 10 thou on intake and 40 thou on exhaust. Looks like the heads have been milled to much only 60cc chambers
Any ideas on a lower lift decent sized cam that will fit, i'm running comp lsr double springs with there retainers.
Cheers for any advice
Yeah I'd say the same about the heads..That 227/239 cam is similar to the one I installed in my engine but my heads aren't milled.... Here's a short vid clip:
https://ls1tech.com/forums/generatio...3-cam-vid.html
Here's one you may be interested in:
the stats are at the bottom of the vid:
http://www.youtube.com/watch?v=HJrmB...eature=related
https://ls1tech.com/forums/generatio...3-cam-vid.html
Here's one you may be interested in:
the stats are at the bottom of the vid:
http://www.youtube.com/watch?v=HJrmB...eature=related
How about a Comp LSR LSL 223/231 or the EPS tweaked version of the LSL lobe @ 222/230. It works great in my G8 with the heads milled .030, no fly cuts and oem head gasket. Results are in my signature below. Good Luck
Thread Starter
Staging Lane
Joined: Nov 2009
Posts: 57
Likes: 0
From: Australia
Thanks guys will dummy fit the other head and manifold to see if any issues there(if say 60 thou machined ther will be an issue there).
How can i measure how much has been milled off heads apart from measuring chamber????
How can i measure how much has been milled off heads apart from measuring chamber????
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Max lift occurs when the piston is travelling down the cylinder on the intake stroke. So unless you have .900" lift you're generally ok.
Judging from the heads being 60cc, it looks like they were milled .048"
If you wanted to make a cam around the PTV issue, it would need intake opening at or after TDC and exhaust closing before TDC..... no overlap.
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Thread Starter
Staging Lane
Joined: Nov 2009
Posts: 57
Likes: 0
From: Australia
Overall lift isn't the issue, depending on cam specs, most often the issue is the intake opening, 240º duration with 110 ICL the intake will be opening 10º Before Top Dead Center, the piston is going up on the exhaust stroke, the exhaust valve is closing, the intake valve is opening before the piston is even at TDC, see the problem?
Max lift occurs when the piston is travelling down the cylinder on the intake stroke. So unless you have .900" lift you're generally ok.
Judging from the heads being 60cc, it looks like they were milled .048"
If you wanted to make a cam around the PTV issue, it would need intake opening at or after TDC and exhaust closing before TDC..... no overlap.
Max lift occurs when the piston is travelling down the cylinder on the intake stroke. So unless you have .900" lift you're generally ok.
Judging from the heads being 60cc, it looks like they were milled .048"
If you wanted to make a cam around the PTV issue, it would need intake opening at or after TDC and exhaust closing before TDC..... no overlap.
I understand your comments cheers.
The specs of my 227/239 are 8 degrees overlap intake opens 1 degree BTDC exhaust close's 7 deg ATDC. Specced from WCCH. 112 lsa on 112 ICL
It's just as the intake valve opens that there close so going to play with cam timing and see if that helps.
Thanks
You've got several problems here that are going to keep you from making good power. The first being PV clearance with any cam with more than a few degrees of overlap - if that. The second problem is going to be running enough timing with that much compression. Any cam that will fit is going to net extremely high cylinder pressure. These heads love timing. Best power seems to be made running 28-30 degrees of advance. I'd be surprised if you can get 20-22 before you run into serious knock. The third issue may be getting the manifold to sit down on the heads with that much milling.
Just my $.02
Just my $.02
Last edited by WKMCD; Jun 13, 2010 at 06:05 PM.
Thread Starter
Staging Lane
Joined: Nov 2009
Posts: 57
Likes: 0
From: Australia
You've got several problems here that are going to keep you from making good power. The first being PV clearance with any cam with more than a few degrees of overlap - if that. The second problem is going to be running enough timing with that much compression. Any cam that will fit is going to net extremely high cylinder pressure. These heads love timing. Best power seems to be made running 28-30 degrees of advance. I'd be surprised if you can get 20-22 before you run into serious knock. The third issue may be getting the manifold to sit down on the heads with that much milling.
Just my $.02
Just my $.02
I'm running 100 octane so comp should be fine. The PTV and manifold not so easy just about to start playing again
Keep the ideas coming
Thread Starter
Staging Lane
Joined: Nov 2009
Posts: 57
Likes: 0
From: Australia
I just couldn't work out why i had such a PTV issue when others have been ok even with out flycutting.
Just worked out as i tighten rocker down its opening the valve even when on base circle of cam pushrods are way to long 7.350 thought they'd be close.
Of to by a pushrod lenght checker and do it right
Dumbarse
Just worked out as i tighten rocker down its opening the valve even when on base circle of cam pushrods are way to long 7.350 thought they'd be close.
Of to by a pushrod lenght checker and do it right
Dumbarse 
Teching In
Joined: Feb 2009
Posts: 15
Likes: 0
Hey Aussie 6L,
I have fitted that exact cam to a few LS3's and had around .080'' PTV on the inlet from memory.
My suggestion is get some new stock heads, .040'' gaskets and keep that cam. You may be suprised how cheap the bare castings are.
I have fitted that exact cam to a few LS3's and had around .080'' PTV on the inlet from memory.
My suggestion is get some new stock heads, .040'' gaskets and keep that cam. You may be suprised how cheap the bare castings are.
Thread Starter
Staging Lane
Joined: Nov 2009
Posts: 57
Likes: 0
From: Australia
Got a pushrod checker tonight so with shorter rods the big cam should be back in soon.
I want the comp up for dynamic compression so i'll stick with the ported one's for now. Dummy fitted manifold and fits well.
Last edited by Aussie 6L; Jun 16, 2010 at 03:35 AM.
TECH Apprentice
Joined: Jan 2008
Posts: 366
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From: Gladstone, Queensland, Australia
I had 36 thou off heads, stock gaskets, with a 240 intake lobe I had 120 thou ptv clearance on 160 thou reliefs so 40 thou interference on a 108 ICL.
The question I ask Paul is. Are you running the Higgins heads.. Do you have stainless valves? If so this is the issue go back to stock LS3 valves and problem solved mate...good luck
The question I ask Paul is. Are you running the Higgins heads.. Do you have stainless valves? If so this is the issue go back to stock LS3 valves and problem solved mate...good luck