I was setting up my valvetrain for my new LPE 403 and found this problem purely because I had the heads off and did it on the bench this time. As I was checking the wipe pattern to set the shim height I was using my dial indicator to measure the valve lift of the new cam, which is .610". As I approached .560" lift the rockers seemed to bind and go no further. I was like, wft? Upon further investigation I found the rockers were bottoming out and indeed binding on the mounting rails. The cam I was running was a .581"/.588" cam. Can you imagine what would have happened if I ran these with my new cam? You will notice that I undercut them previously with a flycutter to get more clearance with the retainers as they were binding on those as well. However, I didn't have a way of judging clearance on the trunion bottom while the heads were mounted.
One other thing I noticed was that even though my car started and ran very quiet as far as the valvetrain goes, my lifters would always bleed down and after it warmed up was very noisey. I think this would explain that, and also my valve guides were worn out after only 6k miles. I've read on here that some complained about thier Jesel lifters floating or flexing. I'm willing to bet they have a similar or the same problem.
Dimples in the steel mounting rail:
Dimples in the trunion bottom. Also notice where the mounting rail bolt has interfered with and cut dimples into the center of the trunion bottom:
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I'm shocked. I can't believe that a rocker that supposed to be 'one of the best' has this kind of issue. Not cool. Good thing you caught it! What's the fix?
__________________
Aaron
'03 Electron Blue Corvette Z06
The normal stuff.....
EFI-101, EFI Advanced, EFILive-101, Variable Camshaft Tuning
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I'm shocked. I can't believe that a rocker that supposed to be 'one of the best' has this kind of issue. Not cool. Good thing you caught it! What's the fix?
I'm shocked. I can't believe that a rocker that supposed to be 'one of the best' has this kind of issue. Not cool. Good thing you caught it! What's the fix?
Well, I'm not saying that this issue is indicative of the product, this is what I found with my install. I am calling Jesel on Monday and sending them the pictures here. I am in no way saying that the design is flawed either. I am pointing out something that is a problem on the set I have and that others may want to check thier's also.
There are 2 fixes I know of:
1: Put them back in the milling machine and clearance the knuckle where the binding takes place by cutting it flat about .050".
2: By Yella Terra's, set them up and install those.
As Bob revealed, I chose door number 2 for now. I'll report back on what Jesel says.
One thing I'd like to point out about the Yella Tera's. They are really a pedestal rocker and not a true shaft like the Jesel's. Consequently, there is no repeatable set point for torqueing them down. You are at the mercy of where the pedestal lands under pressure from the spring as you are torqeing them and where they finally contact the mounting boss. The Jesel's are superior to this because of the way the shaft's mount in the rail. Also the rail fits snug in between the little webs that are cast into the head at the rocker bosses. Also, if you want to get creative you could have dowels fit to the heads and stands and get perfect alignment always. You simply can't get that with a pedestal rocker.
Did you see any issues with pushrod clearance with the Jesel's? I looked at these hard prior to buying the Yella Terra's and several guys mentioned having to grind the heads for pushrod clearance.
I would be interested in Jesel's input as well as these are somewhat the ultimate for rockers.
According to the Jesel rocker installation instructions, they are suppose to be a bolt on replacement provided: the heads have not been machined, and camshaft has not been upgraded. What length pushrods are you using?
According to the Jesel rocker installation instructions, they are suppose to be a bolt on replacement provided: the heads have not been machined, and camshaft has not been upgraded. What length pushrods are you using?
That's correct. My heads have been machined, they are AFR's, and the camshaft was much higher lift. .581"/.588" I was using 4.375 pushrods.
The heads were also milled .030" and I was using an .040" gasket. The heads being milled and a thinner gasket wouldn't give me a bind problem, the higher lift cam would. Also, the wider diameter retainers would give me problems with the undercut.
That's why I'm pointing these issues out. In case someone wants to use these with upgraded cams and different heads.
That's correct. My heads have been machined, they are AFR's, and the camshaft was much higher lift. .581"/.588" I was using 4.375 pushrods.
The heads were also milled .030" and I was using an .040" gasket. The heads being milled and a thinner gasket wouldn't give me a bind problem, the higher lift cam would. Also, the wider diameter retainers would give me problems with the undercut.
That's why I'm pointing these issues out. In case someone wants to use these with upgraded cams and different heads.
Yep, certainly pays to do a little investigating to make sure everything is compatible before buying. I'm thinking you are not using 4.375 pushrods
Did you see any issues with pushrod clearance with the Jesel's? I looked at these hard prior to buying the Yella Terra's and several guys mentioned having to grind the heads for pushrod clearance.
I would be interested in Jesel's input as well as these are somewhat the ultimate for rockers.
I saw one instance on one cylinder where it looked like I was getting contact. This is what led me to check my retainer clearance. After I clearanced them I didn't have clearance issues. It's possible the AFR's are a little more forgiving in that area. I never tried them on stock heads. I will report back what Jesel says/advises. I also want to ask them if they think it will be ok to just flatten out the 'knuckle' and not give away any more strength. I love the way they are mounted, and the shafts are so strong. They are a little heavy, but I never had float and spun to 6900 on the dyno, where I would see it, several times. I will admit that I had my 8017 dual springs shimmed .060" for greater seat pressure.
I talked to tech at Jesel. This is what they said, not quoting. The SS Series rockers are only intended as a replacement for the stock rockers and are not designed to be used in the application of larger cams than stock lifts. They recommend the adjustable SS Series for lifts higher than oem.
Having heard that, I remember reading on the install page or the literature that they are designed for stock replacement only, or something like that.
I then asked what they would recommend as I now have an expensive rocker system I can't use in my current application. They recommended I take off what is necessary from the rail to get the lift clearance I need and not machine the rocker. This seems reasonable at first, however I am still getting interference from the stand mounting bolt heads on the rockers also, as can be seen in the pictures. So it looks like I will have to machine the stands about .050" off the lands surrounding the mounting bolts, and then counterbore the mounting bolt holes .050". For anyone using SS Series non-adjustable rockers please check your maximum lift height. Again, I found approx. .560" lift to be the maximum before interference occurs in my application.
Wow, I can't tell you how many guys are running these on aftermarket setups that are likely not aware of this. The Jesel Mohawks are nice (very pricey though) but I would thing the adjuster over the pushrod would be even heavier even though its on the slow side of the rocker.
Wow, I can't tell you how many guys are running these on aftermarket setups that are likely not aware of this. The Jesel Mohawks are nice (very pricey though) but I would thing the adjuster over the pushrod would be even heavier even though its on the slow side of the rocker.
Another thing that has to happen with Mohawks is a tall valve cover MUST be used. That means you also have to relocated the coil packs.
The issue I am having may have to do with AFR's. I'm not sure how they are different, but I'm sure there are guys running much larger cams than mine was. If that's the case I would assume they would be having problems also and it would be reported.
Additional point: On another board someone made a comment that they don't have this problem with a larger cam, but the 'knuckle' at the bottom is not there on thier's. I'm wondering if I have an early set that were redesigned afterwards. Who knows?
Anyway, my plan is to machine the knuckle off .050" and then check the strength of the rocker in my vise with a spring pressure gauge to make sure it can still hold +500lbs. If not, they have to go in the garbage anyway.
BTW, Tony told me not to bother with them. But I just couldn't listen!
Seems to be more of a geometry/set up miscalulation rather than faulty rockers. I have Jessels and have over 60k trouble free miles with a .595 lift comp cam. Obviously some coil bind going on here.
Seems to be more of a geometry/set up miscalulation rather than faulty rockers. I have Jessels and have over 60k trouble free miles with a .595 lift comp cam. Obviously some coil bind going on here.
Not a geometry miscalc. I had them set up for a perfect wipe pattern. I was running 7.375" pushrods to get .080" preload. I have AFR 205's milled .030" and was running a Cometic .040" gasket. I ended up shimming the Jesel rocker stands .025" for narrow, centered, wipe pattern.
I'm not saying my rockers are faulty. I'm saying I have this problem with them with my application. Just because you aren't noticing any problems doesn't mean you don't have any. I am merely giving a heads-up to users of Jesel SS series rockers. It's not coil bind. If you look at the pictures above you will see the rocker body is binding on the rails and rail mounting bolts at the front of the trunion base. Also, Jesel confirmed this could be an issue.
You are NOT alone in this!!! I ran Jessel shaft rockers with LQ9 heads for 3 years, switched to AFR 225's and had to switch to Comp Cam Adjustables as the Jessels hit the retainers even after some minor maching. Jessel wanted $900 +/- to rework these and make them adjustables. NOT A HAPPY CAMPER AFTER SPENDING $2000 +/- on the JESSELS'. In order to use the jessels I would have to measure and shim each rocker searately - FORGET THAT!!
Are you planning on removing material where the red circles are in the photo above? Got any side shots of the rocker arm itself? I would think that area is a relatively low stress area. Since its at the outer periphery of motion I wouldn't think much would need to come off to clear.
Yes, that's what I'm planning to do. It's more of an experiment at this point since I have the YT's installed and running. I will do the machine work, then stress test them to see if they can take the 500lb. maximum Jesel says they are good for. If they pass, I may put them on in the spring when the weather turns nice.
Corvette Store
Problem with Jesel SS Series Rockers
I'm shocked. I can't believe that a rocker that supposed to be 'one of the best' has this kind of issue. Not cool. Good thing you caught it! What's the fix?
