I was advised to go with the 918's with the lt4 spring seats.

I've heard of plenty of guys running them with no problems. This spring is suppose to be the next great thing. I like the idea they handle such high lift and you dont have to go with a dual spring set-up. I dont feel like pulling my heads off the car.

 

First of all let me say that I am in no way an expert on this topic. I have zero
experience with high performance valve train stuff. I'm just an engineer and
did not like that fact that the spring did not sit flush with the seat. I even made
the mistake of not using the GMPP guideplates and had the roller tips of the
rockers slightly off of center. Although I corrected this, it never caused me
any problems. The LT4 spring seat is probably about the same as using the
Comp guideplates.

What really pisses me off is that I went to all the extra trouble to find and
install a seat that fit perfectly, and yet I still have problems. Once again, a
testimonial for you to not listen to anything I say. I'm just sharing information
that cost me $$ to obtain and it's for you to take and use for free. For all I
know, the 26915s that I installed could be total crap.

 

Mike, your high end miss issues could be valve float, attributable to the springs.

Check your PM.

 

For my setup Combation Motorsports sent me the 918 springs & seat locators. This setup went onto my LT4 heads. I think the reason for the locators is to avoid the gap at the seat. If your planning to use the BeeHive spring, check with Dave or Terry there & they will have your answers.

 

Am I missing something? AFAIC, there is no comparison between the 26918 and the 977, if I got the specs correct.

 

Good info on this thread

 

145lbs seated 313 lbs rate 26918
155lbs seated 441 lbs rate 977

977 with Ti retainers has about twice the effective mass of a 26918 with steel retainers.

As far as RPM range on a motor goes, the 26918 will control the valve better at higher RPM or control a more aggressive cam lobe better.

I personally like a 26918 with Ti retainers on hyd roller setups. Not the cheapest way to go but it works like a champ, if done right you could see well over 7,000rpm on a hyd roller valvetrain.

Bret

 

Well, I've got a hard time accepting that the 26918s will control as well as the 977 do, although the 26918 do a deceptively good job of controlling high rpm valvetrain. To get some idea (as a comparo), how the beehives stackup to conventional wound springs, add appr. 20% to the beehive open pressure, to obtain rate of conventional spring, needed to do same job. However, and of note, the conventionals are not in the same 'ballpark' when it comes to controlling harmonics, as well as the beehives, with their partial coil bind/stackup. Harmonics (control of) can be as important as the pressure itself. For a solid roller setup, the 26918 may be a little lacking. In that case, the 26120 would be a better choice, with it's 148# @ 1.90", and 370# @ 1.30". The downside is, requirement of a longer valve, however.

 

Actually they are better at harmonics than a standard dual spring is. The beehive shape doesn't have a set resonant frequency like a straight coil spring does, and even a dual has two frequencys that it resonates at, they are not a strong as one single spring resonance. The beehives have resonant frequencys too, but there are so many that they are very small in amplitude. Just think of a single big wave (single straight coil) two medium sized waves (dual spring) and a bunch of little waves (beehive). The beehives effect the TQ curve much less thru it's RPM range.

I've tested the 26120's, 26918's and the 977's the 26120's act like a much bigger spring than the 977's even when setup to 155lbs on the seat (identical as a 977)

If you don't believe it, I'm not going to change your mind. I've used them for 1 1/2 to 2 years on SBC/LT1 motors now. Freelance writers like Vizard test them back to back and make good comparisons all the time. Might want to go pick up the PHR Feb 2005 issue in the grocery store and look at pg 79. This is about the 10th mag i've seen a different article on the beehives in.

Bret

 

Actually, though I didn't state either way, a dual spring was implied, by me, as no single would compare pressure wise, or be able to accomodate a given hi perf valvetrain setup.

....the 26120s act like a much bigger spring than the 977s, even when setup to 155lbs on the seat (identical as a 977)

I agree Bret, that they will definately 'act like a much bigger spring' ESPECIALLY when setup pressures are the same, as they are still 'acting bigger' even though pressure are less than conventional (dual) springs. The point to convey, the pressure need not be the same, or even similar, for the beehive spring to be superior, even when discounting an important harmonics comparo. See my post above, regarding 'apples to apples' pressure comparo, for a meaningful overview, according to CC.

The "hard time accepting the 26918" statement, was in reference to what I was told by CC tech. If your experiences show the 26918 being superior to the 977, so be it. According to CC....I question it however. That was the jest of the previous post above. The 26120 is much stiffer than the 26918, and that (26120) spring was (by CC) compared, in similar fashion to a 170#/450# spec (930?) spring, which is a little stiffer than the 977. Anyway, maybe, in this case, CC is not as accurate, regarding the comparo of their spring (the 26918), as someone with experience/actually using this spring. So be it. I've no problem with that.