Valve spring installation question - installed height?

[1FastCSX289]

I got a set of Comp 942's for Christmas and I am going to install them with stock retainers and PT lifters. The seat load on the box reads 115 lbs @ 1.7". Does this mean I set the installed height to 1.7"? Or is there a specific installed height that is specific to our engines? In other words, is the installed height dictated by the spring or the engine?

If my head was set up with stock springs recently, is it imperative that I measure and set the installed height on the new springs? Or is it safe to use the same shims?

Thanks.

[mock_glh]

1.7 is about what our engines use. Little or no adjustment to the installed height should be necessary.

[1FastCSX289]

1.7 is about what our engines use. Little or no adjustment to the installed height should be necessary.

So, does that mean if my last springs were set at 1.7, then I can just drop these in with the same shims?

[2.216VTurbo]

Wait, are you using shims to adjust seat pressure or just the 'wear gaurds' that keep the springs from chewing into the aluminum? 115# should be plenty of seat pressure, did they list an open pressure at X amount lift?

[1FastCSX289]

Wait, are you using shims to adjust seat pressure or just the 'wear gaurds' that keep the springs from chewing into the aluminum? 115# should be plenty of seat pressure, did they list an open pressure at X amount lift?

I will be shimming to adjust seat pressure. The open rate is listed at 284lbs @ 1.2". Brian Bucar recommended the springs and I bought them through TU.

My machinist said to just double check that he set the installed height at 1.7 and then just drop them all in.

Anyone else have an opinion?

[turbovanman²]

Use the stock wear washer, install them. Stock height is 1.7"

[4 l-bodies]

Here is my .02 cents since your asking, Stock installed height is closer to 1.650" on our motors, than 1.700". I have no idea what you have for tip height on your valves, shims, retainers, keepers, etc. ALL of these effect installed height. Obviously, as well as how far down your sinking the valves into the seats too.
My thoughts are you will be very hard pressed to get 1.700" out of standard tip height valves and standard everything else, unless you are sinking the valves too far down.
I use this spring too with roller cams and I NEED to use a .015 thinner spring shim, .040 shorter than stock tip height on valves, +.025 installed height titanium retainer, and special machined keepers, to get installed heights slightly over 1.700"
If your not using that big of a cam, no worries run it at 1.650 or whatever it comes out to be. If you are using a .500+ lift cam, you better be around 1.700 or you will be hurting valve springs by getting them too close to coil bind. Sinking valves down any amount to gain installed height is a serious CFM flow no-no.
Todd Nelson

[2.216VTurbo]

Here is my .02 cents since your asking, Stock installed height is closer to 1.650" on our motors, than 1.700". I have no idea what you have for tip height on your valves, shims, retainers, keepers, etc. ALL of these effect installed height. Obviously, as well as how far down your sinking the valves into the seats too.
My thoughts are you will be very hard pressed to get 1.700" out of standard tip height valves and standard everything else, unless you are sinking the valves too far down.
I use this spring too with roller cams and I NEED to use a .015 thinner spring shim, .040 shorter than stock tip height on valves, +.025 installed height titanium retainer, and special machined keepers, to get installed heights slightly over 1.700"
If your not using that big of a cam, no worries run it at 1.650 or whatever it comes out to be. If you are using a .500+ lift cam, you better be around 1.700 or you will be hurting valve springs by getting them too close to coil bind. Sinking valves down any amount to gain installed height is a serious CFM flow no-no.
Todd Nelson

What's that 115# @ 1.7 like at 1.65 Todd? 125, 130? Sounds like a lot of seat pressure to me Todd, then again, I like those tiny little twice-as-many-per-cylinder valves, 80# on the seat is plenty for those

[1FastCSX289]

Here is my .02 cents since your asking, Stock installed height is closer to 1.650" on our motors, than 1.700". I have no idea what you have for tip height on your valves, shims, retainers, keepers, etc. ALL of these effect installed height. Obviously, as well as how far down your sinking the valves into the seats too.
My thoughts are you will be very hard pressed to get 1.700" out of standard tip height valves and standard everything else, unless you are sinking the valves too far down.
I use this spring too with roller cams and I NEED to use a .015 thinner spring shim, .040 shorter than stock tip height on valves, +.025 installed height titanium retainer, and special machined keepers, to get installed heights slightly over 1.700"
If your not using that big of a cam, no worries run it at 1.650 or whatever it comes out to be. If you are using a .500+ lift cam, you better be around 1.700 or you will be hurting valve springs by getting them too close to coil bind. Sinking valves down any amount to gain installed height is a serious CFM flow no-no.
Todd Nelson

Im using a stock cam. I just wanted to be able to retard the valve timing and rev er up a bit more, so I bought the tighter spring. I wont be sinking the valves anymore.....the head is on the car, already ported and machined, etc. Youre only talking about .050" of an inch difference in installed height. That should only be about 5 or 10 lbs more of closed seat pressure, right? And how much less before coil bind? Just that .050", right? Stock lift is only what, .450" at most? Coil bind is at 1.125". So, that .575" of spring travel.......subtract the .050" that I may be losing and that still .525" I will have. I could still probably run a little larger cam down the road like the FWD-P line or whatever, correct?

[4 l-bodies]

No worries running a bit more seat pressure with a roller cam. Sliders are a lot more sensitive to this than rollers. You are correct, it will be just a bit more than the supposed 115lbs @ 1.70. maybe 125lbs. Maybe less. Stock rollers are .430-.433 lift. That would put you @ 1.220 "if" your currently at 1.650. That give you about .095 before coil bind with the stock cam. As you can surmise, running a heavier spring puts you closer to the coil bind problem, as opposed to running stock springs. No worries until more lift, then it becomes a issue. SB Mopars have this same issue. In fact, the spring you are using is designed for that application.
I have run these springs many times with a stock cam. They work great for me. They are a whole lot better than using old tired 20 year old springs.
It would be nice to know what your machinist set the spring heights at just so you know where you stand in regard to seat pressure and coil bind (for future bigger lift cams). You wouldn't be the first guy that blew up a motor when valve springs coil bind and eject the keepers.
Todd Nelson

Im using a stock cam. I just wanted to be able to retard the valve timing and rev er up a bit more, so I bought the tighter spring. I wont be sinking the valves anymore.....the head is on the car, already ported and machined, etc. Youre only talking about .050" of an inch difference in installed height. That should only be about 5 or 10 lbs more of closed seat pressure, right? And how much less before coil bind? Just that .050", right? Stock lift is only what, .450" at most? Coil bind is at 1.125". So, that .575" of spring travel.......subtract the .050" that I may be losing and that still .525" I will have. I could still probably run a little larger cam down the road like the FWD-P line or whatever, correct?

[1FastCSX289]

It would be nice to know what your machinist set the spring heights at just so you know where you stand in regard to seat pressure and coil bind (for future bigger lift cams). You wouldn't be the first guy that blew up a motor when valve springs coil bind and eject the keepers.
Todd Nelson

Im gonna try and get ahold of a mic or just use a machinist's scale to get an idea. I would imagine he set the height to what stock it supposed to be. With a stock cam, I dont see how I would even be CLOSE to coil bind, especially if I made sure I was in the 1.7" ball park.

[The Pope]

No worries running a bit more seat pressure with a roller cam. Sliders are a lot more sensitive to this than rollers. You are correct, it will be just a bit more than the supposed 115lbs @ 1.70. maybe 125lbs. Maybe less. Stock rollers are .430-.433 lift. That would put you @ 1.220 "if" your currently at 1.650. That give you about .095 before coil bind with the stock cam. As you can surmise, running a heavier spring puts you closer to the coil bind problem, as opposed to running stock springs. No worries until more lift, then it becomes a issue. SB Mopars have this same issue. In fact, the spring you are using is designed for that application.
I have run these springs many times with a stock cam. They work great for me. They are a whole lot better than using old tired 20 year old springs.
It would be nice to know what your machinist set the spring heights at just so you know where you stand in regard to seat pressure and coil bind (for future bigger lift cams). You wouldn't be the first guy that blew up a motor when valve springs coil bind and eject the keepers.
Todd Nelson

I've had them installed 1.65 on the exhaust and 1.68 intake. But that also has a little to do with the seats too. On a used head and old seats 1.70 is fine and is slightly better for bind. Technically there is a flow gain from a 1.65 on our heads, but it increases the compression ratio and bind danger so it isn't worth it.

FYI if you dump the old POS springs and run the Comp beehives (26995) you don't get bing till .600" lift at 1.70 and .550" at 1.65 installed. Magnum engines have the same bind issue.

[1FastCSX289]

FYI if you dump the old POS springs and run the Comp beehives (26995) you don't get bing till .600" lift at 1.70 and .550" at 1.65 installed. Magnum engines have the same bind issue.

Even with them set at 1.65, my bind is still around .525 lift. I dont think I have to worry. And if I switched to beehives, I cant run a stock retainer and lock.