Small Block LS7 heads with LS9 Valves
Thread Starter
Joined: Sep 2007
Posts: 1,637
Likes: 18
From: Sandbox, Kuwait
Small Block LS7 heads with LS9 Valves I have my hands on a L92 engine, and i would like to swap the top end for LS7 heads and intake. I found RHS offer LS7 heads for smaller displacement blocks, but the valves sizes are 2.100" for intake and 1.575" for exhaust.
Since i have a 6.2, i was hoping to install LS9 valves and compcams conical springs on the LS7 heads.
My questions are
Will i have an issue with a lower valve spring install height?
Will i have to use LS7 rockers or may i use LS3 rockers
Will i run into geometry issues between the lower 1.800" and LS7 rockers?
Since i have a 6.2, i was hoping to install LS9 valves and compcams conical springs on the LS7 heads.
My questions are
Will i have an issue with a lower valve spring install height?
Will i have to use LS7 rockers or may i use LS3 rockers
Will i run into geometry issues between the lower 1.800" and LS7 rockers?
TECH Addict
Joined: Jul 2013
Posts: 2,189
Likes: 123
From: Portland, Oregon
You would need to use the LS7 rockers on the LS7 heads due to the intake valve offset.
Why not run a dual spring designed specifically for the LS7 heads? That way you have the correct install height, and no worries about geometry... plus, dual springs offer a safety net that conicals will never give you.
Do you already have the LS9 valves? Those Ti valves are not cheap and require lash caps, just make sure you do your research and have the heads properly set up to use titanium valves.
I have heard, but never personally tried it, that you can run unmodified LS7 heads on the 4.065" bore, just like running LS3 heads on a 4.00" bore. The cylinder shrouds the valves pretty bad, but you can do it. So, LS7 heads with LS3/9 sized valves seems like it should work without a hitch.
Why not run a dual spring designed specifically for the LS7 heads? That way you have the correct install height, and no worries about geometry... plus, dual springs offer a safety net that conicals will never give you.
Do you already have the LS9 valves? Those Ti valves are not cheap and require lash caps, just make sure you do your research and have the heads properly set up to use titanium valves.
I have heard, but never personally tried it, that you can run unmodified LS7 heads on the 4.065" bore, just like running LS3 heads on a 4.00" bore. The cylinder shrouds the valves pretty bad, but you can do it. So, LS7 heads with LS3/9 sized valves seems like it should work without a hitch.
Thread Starter
Joined: Sep 2007
Posts: 1,637
Likes: 18
From: Sandbox, Kuwait
Supposedly RHS LS7 heads 54503 are made for ls3 rockers, so that takes care of one problem, the other would be for me to make sure my machine shop can cut the valve seats to fit the larger 2.165/1.590 valves.
The Ti valves all come with lash caps, and the sodium filled exhaust valves are always good to go.
The Ti valves all come with lash caps, and the sodium filled exhaust valves are always good to go.
FormerVendor
Joined: Aug 2016
Posts: 90
Likes: 0
From: Harbor City, California
Why not just buy a set of properly reworked LS3 heads? We rework LS3 heads to flow almost as much as our LS7 heads.
http://www.americanheritageperformance.com/
http://www.americanheritageperformance.com/
Thread Starter
Joined: Sep 2007
Posts: 1,637
Likes: 18
From: Sandbox, Kuwait
the look of the LS7 intake is much nicer than the LS3, but i will take your advice and pass on the LS7 heads.
Like you said, ported LS3 heads will yield more for less than trying to modify the RHS heads for my application.
The RHS heads retail for $2400, plus new ls3 valves $500, machine shop costs to reseat the valves $$$, and ported LS7 intake $750.
Porting LS3 heads is about not that expensive, the valves are $0, rocker bearing upgrade $120, Trick flow HD pedestal stands $120, and a FAST 102 intake that is only $840, so its a huge savings already with more power yielded.
Like you said, ported LS3 heads will yield more for less than trying to modify the RHS heads for my application.
The RHS heads retail for $2400, plus new ls3 valves $500, machine shop costs to reseat the valves $$$, and ported LS7 intake $750.
Porting LS3 heads is about not that expensive, the valves are $0, rocker bearing upgrade $120, Trick flow HD pedestal stands $120, and a FAST 102 intake that is only $840, so its a huge savings already with more power yielded.
You could find LS7 small bore heads that allow you to run the MSD Atomic intake; however those valves to opt for Titanium would make the heads $$$$.
Are you staying naturally aspirated or nitrous/boosted with this setup?
I know of a set of LS9 heads (Ti intake valves) and even a longblock that needs a rebuild. Also (2) LSA longblocks also needing rebuilds. They are in Southern California.... but anything can be shipped and machined/rebuilt before shipping
Are you staying naturally aspirated or nitrous/boosted with this setup?
I know of a set of LS9 heads (Ti intake valves) and even a longblock that needs a rebuild. Also (2) LSA longblocks also needing rebuilds. They are in Southern California.... but anything can be shipped and machined/rebuilt before shipping
Thread Starter
Joined: Sep 2007
Posts: 1,637
Likes: 18
From: Sandbox, Kuwait
Am starting as Na at first with the option to go mildly boosted.
I will go with ported LS3 heads and valves, for my application it makes the most amount of sense. Save the $$$ for something else down the road...
I will go with ported LS3 heads and valves, for my application it makes the most amount of sense. Save the $$$ for something else down the road...
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