LS Valve Install Height Questions
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LS Valve Install Height Questions Hello, I am assembling an LM7 block with LS1 heads and have run into a few questions for more experienced engine builders.
I briefly worked for Texas Speed and Performance as an entry level cylinder head technician and received some free parts while with the company. I have a set of their LS1 heads, but needed to order and install valves. These heads use 2.1" intake and 1.6" exhaust valves. The intake valves that TSP supplies with the heads are hollow stem and therefor way too expensive for me, so I would like to use regular stainless valves. TSP support confirmed they previously used off the shelf Manley valves for these heads before switching to the hollow stem, so I ordered the set of valves that most closely matched the specs given to me by the TSP support. My problem is that these valves have a .049 difference in overall length, with the exhaust valves being the longer of the two. There were no intake and exhaust valves (with my required diameter) that had the same overall length, but these valves appeared to go with each other since they have near identical part numbers. I now have 4 valves installed (2 of each) and the difference in install height is very clear.
What is the easiest solution to this issue? Do the heads need to have a valve job done or do I need valves that are the exact same length? Would I be able to use a longer pushrod or shim of some kind to adjust the lash?
Part Numbers for items mentioned:
Heads: #PRC-SS237CNC
Exhaust Valves: 660-11365-8
Intake Valves: 660-11350-8
Thanks for the help!
I briefly worked for Texas Speed and Performance as an entry level cylinder head technician and received some free parts while with the company. I have a set of their LS1 heads, but needed to order and install valves. These heads use 2.1" intake and 1.6" exhaust valves. The intake valves that TSP supplies with the heads are hollow stem and therefor way too expensive for me, so I would like to use regular stainless valves. TSP support confirmed they previously used off the shelf Manley valves for these heads before switching to the hollow stem, so I ordered the set of valves that most closely matched the specs given to me by the TSP support. My problem is that these valves have a .049 difference in overall length, with the exhaust valves being the longer of the two. There were no intake and exhaust valves (with my required diameter) that had the same overall length, but these valves appeared to go with each other since they have near identical part numbers. I now have 4 valves installed (2 of each) and the difference in install height is very clear.
What is the easiest solution to this issue? Do the heads need to have a valve job done or do I need valves that are the exact same length? Would I be able to use a longer pushrod or shim of some kind to adjust the lash?
Part Numbers for items mentioned:
Heads: #PRC-SS237CNC
Exhaust Valves: 660-11365-8
Intake Valves: 660-11350-8
Thanks for the help!
Last edited by BMechanic; Aug 11, 2024 at 02:53 PM. Reason: Forgot part numbers
You could run shorter pushrods on the exhaust or you could run an .06 lash cap on the intake valve to make up the difference. Both will have the same install height and the difference is in the length above the keeper groove on the valve stem. The exhaust will be taller and you could machine the tips of the exhaust valve .049 in order to run same length pushrods.
