Installed Spring Height
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Installed Spring Height 2002 LQ4, 862 heads, stock cam reground. My question involves the heads. The company that reground the cam suggested use of Pac 1218 springs. Information regarding these springs reported they were drop in with use of OE retainers, locks etc. They first thing that I noticed was the the ID of the springs was larger then the OD of the retainer so in my mind the spring could possibly move around. It was suggested that I use the top hat style one piece valve seal so I went with that style. After cleaning up and lapping the valves I installed the seals on one head then measured (using a cheap valve height micrometer) and the measurement read 1.95" while the installed valve height specified for the Pac 1218 springs is 1.8", I contacted a local home based headshop to see if I could have them check my measurement. They said not to worry, just install the springs and move forward. They said that the hydraulic lifters will take care of the difference. I have not found this guidance within any information that I have read on the internet. I've also read varying views on where spacers might be installed when the top hat style one piece seals are used and it appears that I cannot remove those that I have installed without damaging them. At this point I am thinking that I need to remove the top hat style one piece seals and go with the other style, purchase retainers that fit the ID of the spring, and add spacers to get to 1.8" installed height.
Can those of you who are experts within this area provided advice on how I should move forward?
Thanks,
Jerry
Can those of you who are experts within this area provided advice on how I should move forward?
Thanks,
Jerry
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From: Florida
Wow lifters will make up for spring installed height that’s a new one lol
Show me pics of how you measured, some height mics have a step that an ls retainer will fit into that changes the read height. Wouldn’t be surprised if that’s where your 0.150 went.
as far as the retainers fitting the 1218 diameter, it’s fine I think half the ls cars on the road have those springs in them by now.
Show me pics of how you measured, some height mics have a step that an ls retainer will fit into that changes the read height. Wouldn’t be surprised if that’s where your 0.150 went.
as far as the retainers fitting the 1218 diameter, it’s fine I think half the ls cars on the road have those springs in them by now.
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Teching In
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I tried using the installed height micrometer differently. I set the micrometer up as you see in the pictures, marked the results on the tool then removed it. I set that measurement up again and set the micrometer on a flat surface. I used the hole measuring part of calipers to measure from the flat surface to where the retainer set on the micrometer. I measured all the valves on one head that way. The installed height as measured that way for all 8 ranged from 1.7965 to 1.8020". The PAC 1218 springs specify 1.8." I don't know what the tolerance range might be.
I am uncertain about how the micrometer should have worked. The keeper set easily upon the indented shelf in the top of the micrometer. It is a cheap micrometer costing $16 and did not come with any instructional information.
Jerry
I am uncertain about how the micrometer should have worked. The keeper set easily upon the indented shelf in the top of the micrometer. It is a cheap micrometer costing $16 and did not come with any instructional information.
Jerry
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Verdad Gallardo TECH Addict
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From: Florida
that design is for older engines that tend to use much larger spring retainers. you need to measure the depth of that recess. it looks like about 0.100 to me. then subtract that depth from the height you read from the gauge.
LS motors were the first commonly used beehive springs so the older designed tools dont fit. first time i did an ls head back in like 2001 it was a pain getting my spring compressor to fit those tiny retainers since my usual work was mostly dual and triple spring bbc and sbc stuff.
LS motors were the first commonly used beehive springs so the older designed tools dont fit. first time i did an ls head back in like 2001 it was a pain getting my spring compressor to fit those tiny retainers since my usual work was mostly dual and triple spring bbc and sbc stuff.
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The depth of the recess measured .1425". When checking height does it become more of a challenge when the top hat style seal is used? I'm wondering if the ones that I have installed are seated all the way down. One of the measurements using the micrometer on an intake valve, was 1.925". Subtract .1425" you end up with 1.7825" which is a bit short for the needed 1.8". I can see the measurement being shorter if the top hat seal is not fully seated but if it is, how does this distance become too short. I can understand through wear that the distance could increase but not reduce. Do you know what the tolerance installed valve spring height is?
Thanks,
Jerry
Thanks,
Jerry
The installed height they specified is more of a reference. You should shoot for an installed height that equals your coilbind height, plus valve lift, plus .060” for clearance.
So a spring with a 1.10” coilbind height with a .600” lift cam, should be installed at about 1.760” installed height.
So a spring with a 1.10” coilbind height with a .600” lift cam, should be installed at about 1.760” installed height.
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From: Wilmington, De
I just noticed that this is a stock cam you are using. I'm not sure why 1218s were recommended for a stock cam. LS6/LS3 springs would have been my suggestion.
As far as install height is concerned, I wouldn't fret over .0175". You'll just be running slightly more pressure. In the case of the 1218, 5.48 extra pounds on the seat.
As far as install height is concerned, I wouldn't fret over .0175". You'll just be running slightly more pressure. In the case of the 1218, 5.48 extra pounds on the seat.
I tried using the installed height micrometer differently. I set the micrometer up as you see in the pictures, marked the results on the tool then removed it. I set that measurement up again and set the micrometer on a flat surface. I used the hole measuring part of calipers to measure from the flat surface to where the retainer set on the micrometer. I measured all the valves on one head that way. The installed height as measured that way for all 8 ranged from 1.7965 to 1.8020". The PAC 1218 springs specify 1.8." I don't know what the tolerance range might be.
I am uncertain about how the micrometer should have worked. The keeper set easily upon the indented shelf in the top of the micrometer. It is a cheap micrometer costing $16 and did not come with any instructional information.
Jerry
I am uncertain about how the micrometer should have worked. The keeper set easily upon the indented shelf in the top of the micrometer. It is a cheap micrometer costing $16 and did not come with any instructional information.
Jerry
The installed height they specified is more of a reference. You should shoot for an installed height that equals your coilbind height, plus valve lift, plus .060” for clearance.
So a spring with a 1.10” coilbind height with a .600” lift cam, should be installed at about 1.760” installed height.
So a spring with a 1.10” coilbind height with a .600” lift cam, should be installed at about 1.760” installed height.
Good post Sir.
