jt1 Posted May 5, 2005 Share Posted May 5, 2005 Motor was running soft, decided to check the valves, and found these: Comp solid roller, Comp ProMag rockers, Comp 977 springs 425# over the nose. Valves are Ferrera 6000 series and are perfectly tight in the guides. I spent a lot of time on the valvetrain geometry and it's as good as I can get it. I suspect guideplate alignment problems, but would like to hear anybody else's thoughts as to the cause. Oil pressure is a little down, compression is down, and the oil filter looks like you're looking at the milky way on a clear night, lots of metal. Motor is already out of the car for complete cleaning and freshening. At least I caught it before it scattered all over the track, but what's the cause? John Quote Link to comment Share on other sites More sharing options...
mark Posted May 5, 2005 Share Posted May 5, 2005 John, Sorry to hear about your engine. At least you caught it before it blew apart. I thought you must be having problems when i could keep up with you down the front straight at CMP. Are you sure they were installed correctly? When I put mine back together I had a couple of rockers put on with the seat side up instead of down. I finally had to get the readers so I could see to put it together. Getting old sucks. Mark Quote Link to comment Share on other sites More sharing options...
jt1 Posted May 5, 2005 Author Share Posted May 5, 2005 I thought it was a little soft at CMP. I found the rockers and had already signed up for VIR-S, so I threw two new rockers on it, changed the oil and went on, go or blow. By the end of the day Sunday it was noticably weaker and lost a little oil pressure. I was lucky. I haven't got it tore down yet, maybe tonight. I'm curious to see how much damage the metal has done. Are you talking about the flats on the rocker shafts for the nuts to seat against being up? I'm 99% sure that wasn't the problem, the way the comp's are machined the nut sets a lot higher if the shaft's reversed and it's real easy to see. John Quote Link to comment Share on other sites More sharing options...
mark Posted May 5, 2005 Share Posted May 5, 2005 Are you talking about the flats on the rocker shafts for the nuts to seat against being up? I'm 99% sure that wasn't the problem, the way the comp's are machined the nut sets a lot higher if the shaft's reversed and it's real easy to see. Yes that is what I'm talking about. Easy to see with the readers! Quote Link to comment Share on other sites More sharing options...
dmyntti Posted May 5, 2005 Share Posted May 5, 2005 It does appear that the rockers where not aligned with the valve tips looking at the pictures. That would indicate an alignment problem from the guides. Make sure the guides you are using are set up correctly for your heads, I think some of the aftermarket heads require a special guide as well as the Chevy LT1 heads. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted May 5, 2005 Share Posted May 5, 2005 You guys have me worried now... I didn't do anything special when I installed mine, but I'm also not running a roller solid, but a roller hydraulic cam setup... GOnna have to dig out a couple of books and do some reading... Mike Quote Link to comment Share on other sites More sharing options...
COZY Z COLE Posted May 5, 2005 Share Posted May 5, 2005 This is why my engine builder insisted on the following to be done to my engine...... Balanced and blueprinted. Bored and honed with torque plates. Block resurfaced/equal decked. Line honed with ARP studs. This is with a hydraulic roller cam... LARRY Quote Link to comment Share on other sites More sharing options...
Mikelly Posted May 5, 2005 Share Posted May 5, 2005 Well I've had all that done... And I know John is a man of means and has probably done all this as well, but I'm concerned about rocker geometry now... Need to check a few things... I'd also add that these cars that Mark and John are talking about, and these motors in particular see LOTS of abuse... We're talking about full rev range to redline for 20-30 minutes at a time for 6-8 sessions at a track event... John and Mark are two of the few select guys on this site who are actually HAMMERING the living hell out of these cars... One weekend at a high performance driving event (HPDE) is more abusive than a year of driving for most of our HybridZ bretheren! Different balls, different wax... Mike Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted May 6, 2005 Share Posted May 6, 2005 Sure looks like an alignment problem to me. If you don't have alignment problems, then the pushrods don't show any wear at the guide plate. If you have wear at the guide plate then there is usually other issues. Quote Link to comment Share on other sites More sharing options...
Turbo Meister Posted May 6, 2005 Share Posted May 6, 2005 It looks like the rocker-arm-studs loosened up and allowed the pushrod side pressure to move the guideplates out of alignment. The subsequent off-center pounding of the rocker-arm by the valve-tip probably caused the damage. I have to use ISKY adjustable pushrod guideplates to center the valvetips on my Edelbrock jr heads. And I have virtually no clearance between some of the intake valve pushrods and the exterior of the port wall. Offset roller lifters would solve my problem. Hope your engine is not too badly wounded, internally. Hanns Quote Link to comment Share on other sites More sharing options...
jt1 Posted May 6, 2005 Author Share Posted May 6, 2005 After further review, I'm 99% the problem is the guideplates. Larry's right that block prep is important, but this one's been sonic checked, line honed, bored & honed w/torque plates, and decked and squared on a Rottler. Deck height checked out within a thou, which is pretty good IMO. On these heads, Canfields, the valves and rocker studs are both moved from stock location. This introduces some angularity to the pushrods, since the lifters haven't been moved. This also means the roller tips have some lateral sweep as well as the normal vertical sweep. The guideplates have some clearance on the rocker studs, and I centered the rollers on the valve tips at zero lift. BUT- some of the intake slots had more clearance than others, and these two rockers are on the valves with the most clearance. I think the extra clearance and the pushrod angle caused all the clearance to go to one side. This is pretty evident because the guideplates are showing dimples worn by the pushrods. But here's the kicker- even at max lift with the rocker pushed to the side as far as it will go, the side of the rocker nest to the roller still doesn't contact the valve tip! Even though it's obvious it has been touching, because it's worn badly. So this tells me something dynamic is going on. I'm theorizing once the roller started getting a flat worn on it, the lateral forces caused by the roller tip scrubbing the valve pushed the pushrod against the guide plate hard enough to cause the pushrods to flex and let the side of the rocker contact the valve tip. The wear on the roller has a pronounced taper along the axis of the roller. My solution is new guideplates with tighter pushrod clearance, and set them up playing close attention to the lateral sweep to equalize it between zero and max lift. Lash caps may be a possibility also. Mike's right about this motor getting hammered. Since it was freshened a year ago with new rings and bearings, it's got close to 4K miles on it, 95% of them on track turning 3 - 7K. Cranking psi was an even 200 when fresh, now it's 115-125. I don't know how much of this is due to the extra metal in the system and how much is normal wear. Anybody got any more thoughts? I'd like to hear them. John Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted May 6, 2005 Share Posted May 6, 2005 Maybe stiffer valve springs and a rev limiter? Total speculation on my part buy maybe valve float is allowing the roller to extend past "full lift", then when the rocker and the valve come back together it is with excessive lateral offset? Either that or a stud girdle (if that is the correct term) to limit lateral movement of the rocker studs. Something is letting the roller tips walk off the side of the valve. Shoot a PM to Grumpyvette and see if he has any insight. Obviously you will have your head check for cracking and the valves reseated when the engine is rebuilt. If your lower cylinder pressures have anything to do with your valve problems, then you have other problems as well. Quote Link to comment Share on other sites More sharing options...
dmyntti Posted May 6, 2005 Share Posted May 6, 2005 I agree with Pop N Wood about the stud girdles being a good idea. You may also want to look at self aligning rockers arms as used on Vortec and LT1 heads. These keep the rockers aligned without the use of guide plates. You may also want to consider if perhaps the pushrods are deflecting under heavy use this could also add to the problem. Quote Link to comment Share on other sites More sharing options...
jt1 Posted May 6, 2005 Author Share Posted May 6, 2005 Got the stud girdle covered: Herbert makes a big beefy one for the Canfield rocker stud spacing. It's a nice piece that makes adjusting the valves easy. It seems to be very stable, in about a year I've only had to make very minor adjustments when checking the valves. I also run a MSD 6AL, generally with a 7k chip. I hit it a lot though, and I've heard drag racers talk about hitting the limiter causing bad harmonics. Been thinking about the valve float. These are the springs Comp reccomends for this cam, and they were new last year. I'm gonna have them all checked. When I discoverd this, the lash was excessive, probably around 0.100". I'm trying to imagine how all this stuff bouncing around could have affected the outcome. Probably didn't help the cam and lifters any, I've got to check them carefully too. I keep coming back to the two rockers that wore being the one's that had the most pushrod/guideplate clearance. All the others look fine, like new in fact. Edit: Don, I've heard about the self-aligning rockers, but have zero experience with them. I seem to recall that retrofitting them to a first gen wasn't feasible. Is this commonly done and I'm ignorant about it? John Quote Link to comment Share on other sites More sharing options...
dmyntti Posted May 9, 2005 Share Posted May 9, 2005 The self aligning rockers arms are the factory setup on Vortec and LT1 heads. I do not know of anyone converting to them but I do not see why they wouldn't work. To convert an engine with SA rockers arms over to regular is add hardened pushrods and guideplates. Quote Link to comment Share on other sites More sharing options...
COZY Z COLE Posted May 11, 2005 Share Posted May 11, 2005 FWIW.... I showed this thread to my engine builder and here are his comments..... "What was the valve lash set at originally and did the lash change? How much clearance is between the rocker arm and the valve spring retainer? Are the push rods bent or worn? Are the rocker arm tips centered with the valve tips looking from the exhaust side? It looks like you have 7/16 rocker arms on 3/8 studs. Guide plates and studs should show no wear at all." LARRY Quote Link to comment Share on other sites More sharing options...
pparaska Posted May 11, 2005 Share Posted May 11, 2005 From what I've read about solid roller cams, you should be concerned about the lifters too. Any evidence of valve float should be a huge warning sign that the rollers on the lifters have suffered (the needle bearings). Either replace or have rebuilt. BTW, it seems I've read that Crane did some research that said that the roller tips don't really turn much if any. My guess is, that coupled with valve float (either from bad harmonics from the rev limiter or worn springs) did the rockers in, and caused the other damage. Quote Link to comment Share on other sites More sharing options...
jt1 Posted May 11, 2005 Author Share Posted May 11, 2005 "What was the valve lash set at originally and did the lash change? How much clearance is between the rocker arm and the valve spring retainer? Are the push rods bent or worn? Are the rocker arm tips centered with the valve tips looking from the exhaust side? It looks like you have 7/16 rocker arms on 3/8 studs. Guide plates and studs should show no wear at all." Larry, thanks for asking for his input. Lash is 16/18, no significant changes until the rollers began to wear. Rocker/retainer is approx 100, with no evidence of contact. Pushrods are straight, but showing guideplate wear on the two rockers in question only. Rollers are centered at 0 lift, but not at max lift. Both are 7/16". The two guideplate slots related to these two failed rollers both show significant, probably 60-80 thou, wear where the pushrod is at max lift. Pete, the lifters and cam are fine. It's all apart and at the machine shop for a good cleaning. Mains bearings have debris scratches, rods have copper showing. Crank doesn't have any damage, some bearing metal deposited, and will be checked closely. Two of the rod bearings, 5&6, were hammered pretty badly. I don't know that it floated any, just that there was a lot of clearance with the worn rollers. John Quote Link to comment Share on other sites More sharing options...
COZY Z COLE Posted May 11, 2005 Share Posted May 11, 2005 All righty.... I'll pass your info back to my engine builder today and get back to you after I see him. I've found out you can never have too much input with our "DAMN" types of set-ups.... LARRY Quote Link to comment Share on other sites More sharing options...
pparaska Posted May 11, 2005 Share Posted May 11, 2005 Any word on why the compression was so low, compared to your as new compression numbers? I'm wondering if the heat treatment on that one guide plate was not good and that's what caused it. Quote Link to comment Share on other sites More sharing options...
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