Open/closed pressure of 987's vs 918's
 

Anybody have the #'s to compare?

Re: Open/closed pressure of 987's vs 918's
 

Thet are almost the same, i dont like how close 987 is to coil bind with around .585" lift. I will post numbers later.

Re: Open/closed pressure of 987's vs 918's
 

Josh....here ya go......

CC987: 1.440 dual spring
130 @1.800
325 @ 1.250
Coil bind: 1.150

Seat pressure: 148
130
Installed height: 1.765
Coil bind: 1.02.....on my TEA 5.3's.

Don't have 918 specs....go with 987's <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Re: Open/closed pressure of 987's vs 918's
 

I disagree about 987 springs being better, they are too close to coil bind to be reliable with valve lift in the .585" range. If you specs listed are with 987 springs than you are wrong about coil bind point, it doesnt change.
Here are 918 specs: 130lbs at 1.800" installed height 318 lbs at 1.200" open(.600")valve lift, and they coil bind at 1.085". With a .585" lift cam like mine that leaves .130" before coil bind, way better than 987 spring!

Re: Open/closed pressure of 987's vs 918's
 

I'll leave the specs to those more knowledgeable than myself. All I can say is 15,000 miles, a hundred or so passes at the track, and playing on the street some, and zero problems with my 987s with 566 lift!!!Im sold!!

Re: Open/closed pressure of 987's vs 918's
 

I have brand new in the box 987s, spring seats retainers and all for sale, goin solid roller. :0 Email me if interested at LTOne4Fun@aol.com

Re: Open/closed pressure of 987's vs 918's
 

LS1derfull....reading the specs straight from TEA's invoice on my 5.3's. I agree coil bind point does not change. Wonder why they read as listed <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

Brian says these springs specs are right and will do .600" lift with no issues.

If you look at the actual specs listed above for the 987, you'll see the 987 and the 918's both have 130lbs @1.800" installed height, though the 987's have a bit more room @ .600" valve lift(325 lbs. @ 1.250"(open)vs.318 lbs. @ 1.200 on the 918, and also have more room before bind at 1.150" vs. the 1.085 on the 918, so based on those specs how is it that the 918 is way better?

Again I agree coil bind should not change and did not notice that the assembled spring heights/pressure and bind specs look funny until you brought this to my attention. I'll give Brian a shout and have him confirm the assembled specs I recieved w/my invoice.

Re: Open/closed pressure of 987's vs 918's
 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by GrannySShifting:
<strong> I have brand new in the box 987s, spring seats retainers and all for sale, goin solid roller. :0 Email me if interested at LTOne4Fun@aol.com </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">GrannySS, you have mail!

Mike, let us know what Brian says....

Re: Open/closed pressure of 987's vs 918's
 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by LowETz:
<strong> LS1derfull....reading the specs straight from TEA's invoice on my 5.3's. I agree coil bind point does not change. Wonder why they read as listed <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

Brian says these springs specs are right and will do .600" lift with no issues.

If you look at the actual specs listed above for the 987, you'll see the 987 and the 918's both have 130lbs @1.800" installed height, though the 987's have a bit more room @ .600" valve lift(325 lbs. @ 1.250"(open)vs.318 lbs. @ 1.200 on the 918, and also have more room before bind at 1.150" vs. the 1.085 on the 918, so based on those specs how is it that the 918 is way better?

Again I agree coil bind should not change and did not notice that the assembled spring heights/pressure and bind specs look funny until you brought this to my attention. I'll give Brian a shout and have him confirm the assembled specs I recieved w/my invoice. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">You are reading the coil bind point backwards, 918 has more space with said lift before coil bind than 987 spring does. 987 isnt 130 at 1.80" either its 138 at 1.750" and thats a closer starting point to coil bind as well. Comp doesnt recc: over .500" with 987 spring im sorry but its true.

Re: Open/closed pressure of 987's vs 918's
 

Well,

Despite the listed specs., fact is I can count A LOT more instances of broken 918's than I can 987's. I haven't heard of anyone having issues with 987's.

--JF

Re: Open/closed pressure of 987's vs 918's
 

Has anyone confirmed a break of a 26918 spring that was NOT of the "bad" batch that went out in the spring/summer of '02? Have any newer blue stripe 918s or older pre-'02 918s broke?

Re: Open/closed pressure of 987's vs 918's
 

LS1derfull.... </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">You are reading the coil bind point backwards </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">OK...I'm reading coil bind specs backwards <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />

You are correct that the 918 beats the 987 by .065 @ point of bind(very marginal)but....that is like saying one guy has .080" of PV
clearance, and the other guy has .100", so .100" is better.......who cares....as long as what you have is what you need, and what you need is what you have.

Along with the 987's higher open pressure of 325 @ 1.250 @.600" vs. 918's 318 @ 1.200 and a coil bind point of 1.150 vs. the 1.085 on the 918, you might consider that one of the several differences in the two springs is the actual make up characteristics of the wire itself used to make the springs.

A couple other possible contributing factors concerning 987 vs 918 coil bind point differences:

(A) 918's are ovate, and 987's are not, which will automatically show some degree of bind
point difference alone. Add to that, the conical shape/ design of the 918 lends itself to an additional degree of tolerance before point of bind.

(B) Spring seat and retainer thickness also are a contributing factor.

I spoke w/Brian @ TEA yesterday to quiz him about the specs on my invoice, reitterating to him that it was my intention to take these springs to 7k rpm's on a .600 lift stick. Told me not to worry,
"those heads are good for .600" lift @ 7000
rpm......enjoy".

He said that the 987 is a sturdier unit that will take more lift/ramp/rpm abuse for a longer period of time than the 918...... hands down, and that,
"that is why all our heads get 987's out the door".......going on to say........."I have never heard of a 987 that was set up properly, and heat
cycled properly fail with .500 to .600 lift..... how many 918's have we heard of snapping at that lift?"

I also recieved an email from Brent @ TEA who set the heads up. Here is his reply:

Mike

Your specs are correct, we check every single one that we put on. The difference is all based on what retainer is used to check this with.
Obviously we used your retainer to check this with, I have no idea how comp checks them, but every 987 we have put on an ls1 sets up just like yours.

Your heads are very safe to run that lift and rpm you desire. I will let brian know about the post or I may post myselft, but you are completely safe.

Let me know how the car dyno's and et's.

Sincerely,
Brent

......I feel confident that the 987 will serve me well....your results may vary.

Mike

Re: Open/closed pressure of 987's vs 918's
 

Fact is 987 wont have 130 psi at 1.800" it will have 120 psi, so if you run 1.750" to get 130 psi than you subtract .560" lift, that leaves 1.190" minus coil bind point of 1.150" equals .040" cleareance before coil bind. That might sound good for 7k rpm to you but it dont to me! And this is with only .560" not .600". If im wrong than why does Comp say springs are only safe to .500" lift?
My experience with checking and using Comp springs for over 15 years is they come in under the pressures they claim, so letting them out some to get coil bind clearance is not real smart either. As for .065" being a marginal difference i disagree, that is make it or break it difference with setting up springs. I am not getting personal here i just dont believe im off on this and i think its very important people know the math on this, and why i find it unacceptable to use 987 spring that comp does not reccomend for LS1.
Also just so its clear, the closer a spring runs to coil bind the hotter the wire runs and the more susceptable to breakage it is, so having some cleareance is not just as good as having more than enough clearance before coil bind.