Brian, I have not missed a shift in the car since I've had the heads/cam on the car. I have Crane 832's going on the heads now

 

If all goes well w/ my mods/heads, you're going to have your hands very full too, even with your new Cam/stall

I'm sure you'll get kicked off before I get to race you anyway.

 

In talking with 2 valvetrain company owners over the last couple of weeks I believe the longterm fix for these cars is going to be going with a 1.450 to 1.500" OD spring. Both feel since these cam lifts keep growing, that a larger OD spring will be needed to control the inertia of the the roller lifter.

Chris

 

A single, big diameter spring is still the best way....

Ed

 

The 918's have room, just shim it up a little for some extra pressure.

 

Ed: Why do you say a single?

 

Verbs = OWNED

 

Less coils, less harmonics. The single would need a flat dampening spring.

 

haha you too, I actually snapped a retainer on my setup. Switched out the jesels for the yella terras.

 

Just in, I also bent 5 intake valves

 

Seems like there has been plenty of people posting with valve float from running the YT's with the 987's. Tis truly the reason I'll never own a set while I have my 987's. People should learn from others problems and change there springs and lifters now if they are to keep running the YT's.

 

Sounds like valve float or a backshift/overrev.

I can't see how you can blame rockers arms.

 

Its called polar moment of inertia, or in short the rotational mass of an object about an axis, been a long time since physics for me as well. Anyway, the extra mass of the rocker makes the job of the spring harder.

The cam moves the lifter, pushrod, rocker, valve, locks, retainer and about half the mass of the spring, it is the springs job to move it all back. The more the mass, the sooner in the RPM band that the spring can no longer keep up.

 

Thanks for that info Brian. What is your rev limiter set at Verbs?

 

I have seen 3 other cars with YT rockers having valve float problems. Maybe the extra weight at the tip pushing a spring already on the edge over the edge?
Springs were: Revs, 918s, 987's

I think you should go 921s or 977s with Comp R lifters.

 

Dont worry Verbin,Ill save the bottle run for ya!

 

Rev limiter at 7000rpms, and the problem is I clearly get valvefloat above 6500rpms.

I never had valvefloat with the standard rockers, and as soon as I put the Yella Terras on I got valve float.

 

Hey Verbs,is your car going to be ready for Sunday?

 

Going with Crane 832 duals good to .650 lift. After talking with a few shops they all said they didn't think the Comp R lifters were mandatory, but couldn't hurt. I only have 40K miles on the car.