What is the safe margin on coil bind vs max valve lift (in general and on the ecotec)? I've heard anythign from 0.025" to 0.060"

I'm looking at using ZZP's 78# springs with comp stage II. ZZP says with their retainers, coil bind occurrs at 0.475" when using their retainers. Comp stage II as you know has a max lift of 0.440/0.436" int/exh.

Using the 0.025" rule I'm more than safe, but using the 0.060" rule, I'm definately not. If i need to have the spring seats machined a mm or two I can, but I'd rather not if this spring is adequate. FWIW I will not be revving above 7500rpm.

Thoughts/concerns?

Listening...

No suggestions? i guess I'll go with the zzp springs and see what happens.

Whats the install height? I have read that .060" is a VERY save margin, and is the margin that is used with most DOHC higher revving motors. Doesn't the GM build book recommend 0.060" to be safe......

Revving to 7500 I would be more worried about the stock crank pulley expanding and taking out the stock oil pump gears. If you want to rev to 7500 I would get the GM hardened oil pump gears...to be safe.

GM wrote:These hardened oil pump drive gears are a direct replacement for your stock oil pump gears. When extended time is spend on your rev limiter, or 2 step rev limiter, failure of your stock oil pump drive gears can occur due to the expansion of the crank pulley. The expansion is just enough to crack or shatter the inner drive gear and damage your engine. These hardened gears are a direct replacement and eliminate the fear of causing further engine damage.

GM Racing Hardened Oil Pump Drive Gears 2.2L & 2.0L Ecotec [AE-0022]





Edited 2 time(s). Last edited Thursday, March 11, 2010 1:29 PM

PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO

IIRC , .060 is pretty much the "Standard" for a safe,higher reving motor, .100 for a "High" rev motor. I know alot of guys run .040-.045 all day long on motors that are in the 62-6500 range and don't have a problem.





"The FACTS are always subject to CHANGE once the TRUTH is applied"
"In the entire history of man the only stupid questions are the ones that don't get asked"

I have a question

how many people on this site even knows how to check coil bind on a spring compressor?

-Ben

I have a question

how many people on this site even knows how to check coil bind on a spring compressor?

-Ben

"The FACTS are always subject to CHANGE once the TRUTH is applied"
"In the entire history of man the only stupid questions are the ones that don't get asked"

To check the coil bind height, you continue to compress the spring and the linear increase in pressure suddenly spikes, the back off the the last progressive pressure reading. This height will be the coil bind height.

As for safety margin, 0.060" is standard. Some coil manufactures use more. IIRC, Comp Cams typically uses 0.100". Things that will affect the amount of the safety margin are max lift (duh), ramp rate and operating rpm. Typically, using the cam grinders recommended spring are best.

I definitely would not use a spring with 0.025" safety margin, unless you like rebuilding your motor. Always double check (or have the shop show you on the head ) the spring installed height to verify it is correct. I even had a shop try to tell me the installed height of the stock springs would be okay for my cam, which I knew better. I took my head and parts to another shop 40 miles out of town. The check everything for me right there and I was correct. If I had turned the motor over with the other shops specs, I would have broken parts. The second shop did my work for me, even custom making a pilot guide for cutting my spring seats (10 minutes on a lathe with a piece of bar stock.)

Ben, the springs were designed for the eco head, and the coil bind figure was given at 0.475"

Thanks for the feedback everyone. With such margins, it makes one wonder how any of the cars with stock valve springs running any of the comp grinds are running. They are probably about 0.060" PAST coil bind lol.

So, after all, i should not run anything more aggressive than the "stage I" grind with these springs to be in that generally safe range. If I want to take a chance and deal with a total of 0.035" safety margin, i could run the "stage II" grind.

Thanks again

I think ZZP has these springs to help with people running stock lsj cams that maybe want to turn a little higher rpm and still be safe.

jmarks82 wrote:I think ZZP has these springs to help with people running stock lsj cams that maybe want to turn a little higher rpm and still be safe.

Maybe. They have the coil bind spec right on their site as 0.475" when using their retainers. That does give some room for more lift though - just how much? It would seem 0.415" would be perfectly acceptable. More at your own risk

Like i said, with all the people running comp grinds on stock valve springs, I think any upgrade would be a big plus

Madjack wrote:
To check the coil bind height, you continue to compress the spring and the linear increase in pressure suddenly spikes, the back off the the last progressive pressure reading. This height will be the coil bind height.

ding ding ding we have a winner

one thing i want to add, first you pull the handle down to 1.35" witch is installed height on an eco head. that will give you seat pressure. then you pull the handle all the way to full compression of the spring. that will now be coil bind and max spring pressure. then find out how far you pulled the handle, lets say you pulled it to .750. that will give you .600 lift springs. but good engine builders say you need .050 clearance at your cams rated lift, thats why i used a spacer to bring mine to about 1.28ish installed height. witch in my case gave me about 20 more lbs of seat and around 50 more lbs of "over the nose" pressure.

thats all i can think of now, dont be scared to call or txt
989 798 0518
-Ben

Madjack wrote:
To check the coil bind height, you continue to compress the spring and the linear increase in pressure suddenly spikes, the back off the the last progressive pressure reading. This height will be the coil bind height.

ding ding ding we have a winner

one thing i want to add, first you pull the handle down to 1.35" witch is installed height on an eco head. that will give you seat pressure. then you pull the handle all the way to full compression of the spring. that will now be coil bind and max spring pressure. then find out how far you pulled the handle, lets say you pulled it to .750. that will give you .600 lift springs. but good engine builders say you need .050 clearance at your cams rated lift, thats why i used a spacer to bring mine to about 1.28ish installed height. witch in my case gave me about 20 more lbs of seat and around 50 more lbs of "over the nose" pressure.

thats all i can think of now, dont be scared to call or txt
989 798 0518
-Ben

sorry computer is slow


Overall Best times

60' - 1.857 (6/24/07)-(Drag Radials 205-50-15)
330' - 5.552 (6/24/07)-(Drag Radials 205-50-15)
1/8 - 8.644 (7/25/08)-(Hoosier Drag Radials 225-50-15)
M.P.H. - 82.05 (4/20/08)-(Hoosier Drag Radials 225-50-15)
1000' - 11.229 (7/25/08)-(Hoosier Drag Radials 225-50-15)
1/4 - 13.410 (7/25-08)-(Hoosier Drag Radials 225-50-15)
M.P.H. - 104.95 (4/20/08)-(Hoosier Drag Radials 225-50-15)

** ALL MOTOR **
* 193whp @ 7600 rpm *
* 149 tq @ 5100 rpm *

Website: www.benwenzeljr.com

2005 GM Small Car Bash - Lost 2nd rd - H2 Class
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2009 GM Tuner Bash - #6 in the Q8 (2008 ponitac solstice)