Valve Spring Installed Height 1.900 ????
cant remember which ones they are... but there are 2 types... one version has seats built in with them... the other version is just the vale guide seal with no seat
and they are different for the intake and the exhaust....brown and black...cant remember which is which off hand, but its says on the bag...
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The question about which valve guide seals would be used was to the OP since he's saying that he is using the PAC valve seats. I was just wondering if he realized the OEM valve guide seals have a built in spring seat.
BTW - I like the OEM guide seals. In 2002 is when GM made them one piece. Brown is EX, black is IN ... it's also stamped on the top of the rubber piece on each seal.
BTW - I like the OEM guide seals. In 2002 is when GM made them one piece. Brown is EX, black is IN ... it's also stamped on the top of the rubber piece on each seal.
The question about which valve guide seals would be used was to the OP since he's saying that he is using the PAC valve seats. I was just wondering if he realized the OEM valve guide seals have a built in spring seat.
BTW - I like the OEM guide seals. In 2002 is when GM made them one piece.
BTW - I like the OEM guide seals. In 2002 is when GM made them one piece.
both are OEM and both can be bought at any GM Parts counter..cheap too..
1st design or 2nd design
GM Part #'s
Intake: 12533586 (1st) & 12482063 (2nd)
Exhaust: 12457652 (1st) & 12482062 (2nd)
1st design is without seats
2nd design is with seats
if you use shims with the 2nd design, your shims will go on top of the seats, not underneath..if you put shims under the second design it doesnt seal because you have also shimmed the seal up by that far as well...
I prefer the ones without seats as it allows you to use a much higher quality seat, shims, and you can use a larger diameter seat/shim for larger diameter springs
also, depending on the head and what valve guide is on it... you cant use the all in one 2nd version...if you have the bigger valve guides(like PRC heads have) then they wont even go down... the seal is the same size at the top... the hole for the valve guide needs to be bigger in the case of some aftermarket heads.
Thread Starter
Staging Lane
Joined: Mar 2006
Posts: 74
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From: Metro Detroit
So i got the correct tool for measuring...BIG Difference. Now i am showing my installed height at 1.750
So i guess i am too short. It must be the spring seats.
Thread Starter
Staging Lane
Joined: Mar 2006
Posts: 74
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From: Metro Detroit
So it looks like i will be getting new springs.
1.750 - 1.140 gives me 610. So realistically with my current setup i should not be running a cam with a cam larger then 560 to stay .50 away from coil bind.
1.750 - 1.140 gives me 610. So realistically with my current setup i should not be running a cam with a cam larger then 560 to stay .50 away from coil bind.
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Verdad Gallardo sounds like you need new springs... and possibly thinner seats...dont know how thin your current ones are or if you can even get something thinner or not..
also..if your top measures 1.75...it may be smarter to look into some different valves that get you to the correct 1.8 install height...especially if the heads were bought from a vendor and are currently off the car..
Thread Starter
Staging Lane
Joined: Mar 2006
Posts: 74
Likes: 0
From: Metro Detroit
sounds like you need new springs... and possibly thinner seats...dont know how thin your current ones are or if you can even get something thinner or not..
also..if your top measures 1.75...it may be smarter to look into some different valves that get you to the correct 1.8 install height...especially if the heads were bought from a vendor and are currently off the car..
also..if your top measures 1.75...it may be smarter to look into some different valves that get you to the correct 1.8 install height...especially if the heads were bought from a vendor and are currently off the car..
are you 100% positive you measured correctly, and did you check more than one valve?
also, did you properly seat the retainer and locks...sometimes you have to give them a little tap with a socket or a hammer to get them to fully seat...which could make up the height difference..
Did the retainer fit correctly in the micrometer, i.e., the beehive retainers may not sit on the correct measuring surface of the micrometer.
stock z06 heads should be a 1.8 installed height.
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When I put some PAC 1518 valve springs in my stock Z06 w/ LS6, I measured the installed spring height was 1.775 ~ 1.777". I think the Service Manual says 1.800 +/- 0.025" if I recall correctly.
Of course, in my case I didn't really have to worry about being so close to coil bind.
Of course, in my case I didn't really have to worry about being so close to coil bind.
On The Tree
Joined: Feb 2009
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I say +/- .025 is crap, but COMP says +/- .020 is OK. I still don't like it. That could be up to a .050 swing from one valve to the next, could be the difference between a long happy life and coil bind. When I build heads I set them up to +/- .005 for installed height.
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Well, obviously a stock LS1 or LS6 isn't going to so critical in the cam/spring combo that +/- 0.025" from target 1.800" installed spring height it going to grenade an engine or not. When you got guys using 0.650" lift cams with springs that are rated for 0.650" lift, then you've basically got zero room to spare and setup is obvious very critical.
Obviously none of you know that the LS6 valves are longer than a standard LS2 valve in a 243 head. They are longer because the LS6 cam (02-04) were regrinds and used alot smaller dia base circle lobe. They used longer valves in the LS6 applications so they could still use a 7.400 pushrod. That is why when using the LS6 cam in most other LS applications, you have to normally use 7.450 pushrods to get close to the correct preload.
IF that is why you see a higher installed height then that is why. I would not just use a valve spring mic, but also maybe a vernier caliper with the height checker on the other end will back up your results.
IF that is why you see a higher installed height then that is why. I would not just use a valve spring mic, but also maybe a vernier caliper with the height checker on the other end will back up your results.
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that measurement doesnt sound correct unless you have replaced the valves with non stock valves...
are you 100% positive you measured correctly, and did you check more than one valve?
also, did you properly seat the retainer and locks...sometimes you have to give them a little tap with a socket or a hammer to get them to fully seat...which could make up the height difference..
Did the retainer fit correctly in the micrometer, i.e., the beehive retainers may not sit on the correct measuring surface of the micrometer.
stock z06 heads should be a 1.8 installed height.
are you 100% positive you measured correctly, and did you check more than one valve?
also, did you properly seat the retainer and locks...sometimes you have to give them a little tap with a socket or a hammer to get them to fully seat...which could make up the height difference..
Did the retainer fit correctly in the micrometer, i.e., the beehive retainers may not sit on the correct measuring surface of the micrometer.
stock z06 heads should be a 1.8 installed height.
Last edited by Redchevy1540; Jul 6, 2013 at 01:52 AM.
My stock 241's came in at 1.765" installed height stock. The 1.800" number you see everyone quoting is simply a number used by spring manufacturers as a base for seat value, nothing more. I have never set up stock heads with new springs that came in at 1.800", they have all come in at a lower value.
