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Back in April coming home from work one Friday the Denali developed a pronounced tap. Discovered a broken #6 intake rocker that had evacuated the bearings.
Last week had the same thing happen to #5 intake. Luckily I ordered 3 rockers last time just for this situation so it was an easy fix.
I guess it is time to order a trunion kit and do the whole lot to keep this from leaving me stranded on a road trip. I have a Comp trunion kit on the racetruck and seems to be holding up well. The Denali is my daily with a mild cam and PAC double springs so no need for a max duty piece. Any reason a captured bearing kit like the Comp kit wont serve me well? I just have reservations about the solid bushing kits on high mileage applications.
Also, I haven't found anything on my limited research, but any reason the offset intake rockers are more prone to ejecting the bearings over the straight rocker?
Last edited by BigKID; 08-02-2021 at 11:41 AM.
Reason: brainfart
If you have offset rockers on the exhaust valves, that's your problem
Kidding aside, it depends on a lot of things...lobe profile, valve train mass, spring rate and seat pressure, RPM, oiling...all the things.
...brainfart on my end, yes, offset INTAKE rocker, OP edited.
Cam is a TSP S1 VVT, 212/218 .600/.600 112+6, PAC .660" dual springs 160# closed / ~391# open, ti retainers, 7.40 pushrods (TSP recommendation, didn't measure preload myself). Been running in this configuration since Oct 2018, ~39K miles.
Any reason a captured bearing kit like the Comp kit wont serve me well? I just have reservations about the solid bushing kits on high mileage applications.
The roller bearing kits damage the trunnions on all those type kits. There is a long thread over at tech on this issue and IIRC it happens within a short running time. I'm two years on the Smith bronze kit with no issues running .629" .615" lift. I wish I would have spent the money on the CHE bushing kit for the better design and no press needed install.
So I read thru a few threads on Tech this afternoon and I am in no better position to make a decision as I was before. There pros and cons to each type. I think WS6store has the right answer with their caged roller setup. The roller is axial lubing, the larger roller bearing distributes load better than needle bearings and doesn't have the wear of a bronze bushing. However, they are currently only offered for cathedral heads. Coming in second is the CHE floating bronze bushing that allows the bushing to rotate to wear evenly as opposed to the bottom load wear of the pressed in bronze options. Both bronze styles provide a larger surface area for load distribution. Following would be one of the needle bearing options with the hardened internal race such as the WS6Store or BTR V2. Then there are the multitude of needle bearing options where the bearings ride on the trunnion which may or may not be properly hardened. Most of the failure pics I have seen on these (like the one Red posted above) indicate a metallurgy issue. A hardened inner race or a properly hardened trunnion with proper lubrication could prevent this although the load is still distributed on the small needle bearings.
One of the drawbacks I envisioned with the bronze bushing was the lack of positive oiling. I like how one of our own PTN members compared it to the wrist pin/rod bushing that only relies on splash oiling and somehow lives when the issue was brought up in one of the Tech threads. That made me feel more comfortable about the bronze bushings by looking at it from that perspective.
I have 50k miles on my Trunnion kit pushing it daily and shifting at 7k. My buddies Tahoe with the exact setup as mine minus Trunnion upgrade just ate his first rocker this week at 10k miles. I don't think the roller bearings like rpm plus his had like 130k on it before Maggie and cam. I upgraded mine at 50k when I did my top end and I'm over 100k now with no issues.
I've put over 180k miles on the comp trunion kit with a 212/218 .560/.566 114 cam and Isky 165A springs. No issues with that. But she burns a ton of oil so time for rebuild.
I ended up going with the Summit Bronze Bushing kit. Other than the dirty tooling oil residue, the kit looked quality. The trunnions have a flat on the top inner side with an oil groove the circumference of the trunnion to lube the id of the bushing. The bushings pressed in easily with minimal sluffing. I did use some Lucas assemble lube on installation to help with the presumed dry start issue of the pressed in bronze kits and noticed no abnormal noises on startup other than a little clickity-clack till the lifters pumped up.
As for the old bearings, I did not identify any that were pending immediate failure but all of the trunnions had wear on the bottom side from the inner race. It is possible the bottom needles flatten out then cause the race to rotate on the trunnion. This eventually weakens the race to failure or causes enough slop for lateral load to break the race or retainer.
08-02-2021, 10:46 AM
Two rockers in two months
...brainfart on my end, yes, offset INTAKE rocker, OP edited.
