2.17" Intake Valves - WTF...
Thread Starter
Joined: Nov 2001
Posts: 5,649
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From: Warr Acres, OK
2.17" Intake Valves - WTF... A friend and I looked at a set of LS1 heads today that were worked over by a local "performance" machine shop that has a pretty good reputation of doing good work. They were ported, and had larger valves installed. We disassembled one cylinder to see what they used and how they were set up. They had 2.17" intake valves and 1.6 exhaust valves. (Manley) They had Comp 941 springs that were set at 1.665 installed height.
1. Doesn't that seem like too large of an intake valve for a non bored LS1? (valve shrouding)
2. The 1.665" installed height seems way wrong for 941 springs, hence my other post about installed height and coil bind.
We measured 1.800" from the head with no spring seat to the bottom side of the retainer. If you use a stock LS1 spring seat (.035") that would set the installed height at 1.765". If you use a stock LS6 spring seat (.045") that would set the installed height at 1.755". These heads had the LS6 spring seats plus .090" of additional shims. We were looking at converting these heads over to 918 springs and installing on them on my friends car, but when we saw the 2.17" intake valves, we stopped and thought we would get some opinions on them since 2.08 valves are the largest we've heard of people using.
<small>[ August 04, 2002, 11:47 PM: Message edited by: 2xLS1 ]</small>
1. Doesn't that seem like too large of an intake valve for a non bored LS1? (valve shrouding)
2. The 1.665" installed height seems way wrong for 941 springs, hence my other post about installed height and coil bind.
We measured 1.800" from the head with no spring seat to the bottom side of the retainer. If you use a stock LS1 spring seat (.035") that would set the installed height at 1.765". If you use a stock LS6 spring seat (.045") that would set the installed height at 1.755". These heads had the LS6 spring seats plus .090" of additional shims. We were looking at converting these heads over to 918 springs and installing on them on my friends car, but when we saw the 2.17" intake valves, we stopped and thought we would get some opinions on them since 2.08 valves are the largest we've heard of people using.
<small>[ August 04, 2002, 11:47 PM: Message edited by: 2xLS1 ]</small>
Re: 2.17" Intake Valves - WTF... I didn't think anyone made a valve larger than 2.100" for the LS1/LS6 heads. Could your valves have been machined from blanks? If they are custom machined from valve blanks, then you should check the tip height relative to the spring pad on the head. It should measure 2.00". Any more or less could cause some issues with pushrod length. Just my $.02
Richard <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Richard <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Thread Starter
Joined: Nov 2001
Posts: 5,649
Likes: 9
From: Warr Acres, OK
Re: 2.17" Intake Valves - WTF... I don't think they were made from blanks. They had Manley stamped on them. I had some stock LS1 valves to compart them to. The stock intake I checked measured 2.000", so I'm pretty sure I was measureing them correctly. They were the same height as the stock valves and the keeper slot was in the same location. The problem is that the person that had the heads built doesn't really know how they were built. I think he just took some new bare castings to the machine shop and said "build me some performance heads". He's now trying to sell them to my friend.
Teching In
Joined: May 2002
Posts: 48
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From: Houston
Re: 2.17" Intake Valves - WTF... On a stock bore LS1 I would not use anything larger than a 2.055" intake valve. Any larger than this and shrouding becomes a problem. Also, port cross sectional area would have to be seriously increased to take advantage of a 2.17" intake valve.
Paul J.
Paul J.
