Why did my Jesel's do this?
 

I have a 99 C5 stock bottom end. AFR 205's milled .030" mounted with .040" Cometics, running a 224/228 .581"/.588" 112lsa +0 cam. Kooks headers, Stingers, FAST90/NW90, and other less interesting stuff. I originally had the stock rockers and had HS rebuild them. The car ran great and had a nice lope at idle, nothing crazy, but you knew there was a cam in there. MAP was ~55kpa at 800rpm idle. I had some Jesel SS rockers and installed them. I set the preload to .050" and ground out the valve covers, etc. The car runs great with these in also. The weird thing is, it idles like stock again, the lope is gone. The valve train is quiet. I have lowered the idle to 700rpm's and it is positively stealthy. The MAP at 700rpm is 37kpa, just about what it was at stock. I'm going to the dyno asap to see if this has detuned the car, but it doesn't seem so SOTP, however, we all know how accurate the butt-o-meter is. I actually like it better the way it is, I just can't explain it to myself. Any ideas?

I was reading a while back - how to check if your cam is too big, you back off on the adjusters which effectively reduces duration and increases LSA. It sounds like either the rockers have changed the geometry of they're 1.5s or something instead of 1.7s?

These are 1.7's and the SS's are the non-adjustable rockers. I thought about that but I set the preload to ~.050". I measured it with a dial indicator, I've done this a bit so I know I set it up and measured correctly. One thing I might have overlooked though is pushrod clearance in the head. I have the heads milled .030" and sitting on .040" gaskets. I had to use 7.300 pushrods to get ~.050" preload. So the geometry is different, even though it may be just a shorter distance between the cam center and the rocker fulcrum. But, if the pushrods are hitting the against the heads the lifters could be bleeding down. Does that make any sense? The valve train is quiet though. I'm using Comp 850 lifters.

This same scenario happened to my friend. We put a set of heads on, and shimmed too much (it turned out). It was a 231/237 112+4 and it did NOT lope at all. Then, a month or so later, took out the shims, and it loped like it should. My guess is you aren't getting the full amount of lift.

That does make sense. I did shim the springs an extra .060". I had the HS rebuilt stock rockers on after the shimming though and it loped and ran fine. But you have me thinking. Could the Jesel's be giving me that much more lift that I'm going into bind? Or is the open pressure with the Jesels that much more on the lifters that they are bleeding down? According to my calcs and measurements the installed height was 1.790" with an .060" shim on the intake, and 1.805 with .045" on the exhaust. That is the way the AFR's came set up. I then installed .045" on the intake and .060 on the exhaust. So, that leaves me with 1.745" on the intake and exhaust. Subtracting .060" for bind clearance gives me 1.685". If coil bind is 1.080" (advertised) that leaves me with .605" max lift. I have a .581"/.588" cam and think I should have enough clearance for it.
It IS acting like the lift is getting chopped off though.

I mean to say, we shimmed the rockers, not the springs. We left the springs as they were from AFR.

Your pushrods are not hitting or rubing giving you false preload measurement. I had Jesel rockers with stock 99 heads and had this problem. Just a suggestion.

Oops. Sorry, my bad. I didn't want to shim the stands and loose some rigidity of the rocker system.

I'm thinking it has to be something like this. Or they are not lined up in the pushrod hole.

Put a 7.4 pushrod in and shim the rocer arm stands as needed. You AREN'T going to loose any strength by doing it.

What ever came of this?

Ok, I just finished getting this all sorted out this weekend. It took a while to get everything set up correctly. The most important problem I had was in another thread I posted that I was backfiring randomly at idle and stumbling at high load and lower rpm's. I had bad spark plug wires, changed those and still had the backfireing but cured the stumbleing. The backfiring turned out to be a couple of fouled plugs, from the bad wires.
Onto the Jesel's issue. While I was playing around trying to find the backfiring I removed my Jesel's and noticed a halfmoon shaped indentation underneath near the flucrum about the size of mt retainers and about .010" deep. I remounted the rockers with a piece of paper under them and found the retainers were hitting the rockers. I got out my dremel and relieved some of the fulcrum where the indentaion was and checked again with a piece of paper and no bind. Bolted it back up and had my lope and idle kPa back. This was enough to kill some lift because the roller wasn't on the valve tip at full close. I dodged a bullet because there is no significant guide wear and the valves aren't bent. I also ended up with the narrowest wipe pattern just a tad to the intake side with the stands shimmed .025" and using a 7.350" pushrod with ~.070" preload.

Not sure how much material you removed or how deep, but be careful of the fatigue life of the rocker arms as that location is likely in a high state of tensile stress during operation.

Understood. I only took out about .050" and left the sides intact.
Also, I referenced this before I modded them. http://www.jeselonline.com/board/viewtopic.php?t=15

Hey Roger....

"Bolt on" huh??.....LOL

Good thing I didn't get to you sooner....my advice was going to be to hit the dyno and see whats up (that could have been ugly!).

Keep us posted if you do hit the rollers...

:cheers:

:confused: im confused a tad.
if im reading this correctly, the rocker arms hit the retainers, and bound up. where did that motion of the pushrod going up go? did it bend the pushrods or what? :confused:

Hey Tony! :lol: That's what Steve was telling me all winter. But I just HAD to find a way to make these work. You should see the valve covers. Nothing left inside, hogging them to fit these in there. Planning on dyno'ing in a bit, as soon as the weather changes. We also put in a new operating system in the PCM's, a 2002 Z06 so we could get to the higher resolution tables and better PID selections. I'm still loving the whole package. Maybe even pick up a few ponies. Result's to follow.

Yes, they hit the retainers, but didn't bind up. The were just tilting the retainer slightly, maybe .020", I'm not sure, I didn't measure it. I didn't run the car much at all in this condition. I'm sure the motion of the pushrod going up was absorbed by the retainer's tilt and possibly a touch of the lifter. It didn't bend the pushrods. There was plenty of motion, just that the lifter had to move maybe .020"-.030" before the roller started to push the valve down. Remember, there is a 1.7:1 ratio. So for .030" at the roller tip, the pushrod only has to go around .018". At least that is what I believe saved them. I'm sure if it was any worse it WOULD have been ugly as Tony said above.

thanks for clearing that up.
and thanks for the heads up on something to check for before running the motor... :)