valvetrain problems at track-Need help
valvetrain problems at track-Need help L92 heads, Patriot Gold Extreme double springs, crane hydraulic roller lifters, Harland sharp adjustable rockers, 6500 rpm max, 65# oil pressure, custom cam 224/234. Lash checked with last spring install
Ran 10 laps at Mid Ohio-->> loud lifter noises. Took off valve covers- one jam nut completely fell off- adjustercup on the pushrod backed out. recovered, Re-adjusted, checked both sides-->>> engine quiet
Ran again 4 laps, lost power. Came in, valve covers off-- now same event happened under the other valve cover, jam nut off of one rocker, backed out, pushrod cup trashed/flattened-- weekend over
lots of play in the other rockers- able to push down some of the lifters under the rocker while the engine is still hot.
WHATS THE PROBLEM?
Valve lift?
Too much spring pressure?? beating out the lifter. Previous standard beehive springs, made torque fall off the cliff at 6300 rpm.
or
Bad lifters to start-- why several bad?
What to do next? Is it EZ convert to solid lifters from here, or should I try other spring lifter combinations?
What spring lifter combos have worked for you guys? Need this for a roadrace car track, running 3000-6500rpms for 30 minute periods, must stand up to heat and abuse.
Ran 10 laps at Mid Ohio-->> loud lifter noises. Took off valve covers- one jam nut completely fell off- adjustercup on the pushrod backed out. recovered, Re-adjusted, checked both sides-->>> engine quiet
Ran again 4 laps, lost power. Came in, valve covers off-- now same event happened under the other valve cover, jam nut off of one rocker, backed out, pushrod cup trashed/flattened-- weekend over
lots of play in the other rockers- able to push down some of the lifters under the rocker while the engine is still hot.
WHATS THE PROBLEM?
Valve lift?
Too much spring pressure?? beating out the lifter. Previous standard beehive springs, made torque fall off the cliff at 6300 rpm.
or
Bad lifters to start-- why several bad?
What to do next? Is it EZ convert to solid lifters from here, or should I try other spring lifter combinations?
What spring lifter combos have worked for you guys? Need this for a roadrace car track, running 3000-6500rpms for 30 minute periods, must stand up to heat and abuse.
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Joined: Feb 2006
Posts: 1,170
Likes: 1
From: Rockfield Kentucky
We found that is we lost control of the valvetrain it would loosen everything. On the dyno we could not keep the jam nuts from backing off no matter how we set the valves.
I would check the installed height of the springs as well as the seat pressure. Also talk to the cam vendor about the design of the ramps on the cam. That cam should be a gentle on the valvetrain but one never knows.
I will be back on the spin tron shortly with an LS engine using several hydraulic roller cams. We hope to show some examples of what is happening with that testing.
Robin
I would check the installed height of the springs as well as the seat pressure. Also talk to the cam vendor about the design of the ramps on the cam. That cam should be a gentle on the valvetrain but one never knows.
I will be back on the spin tron shortly with an LS engine using several hydraulic roller cams. We hope to show some examples of what is happening with that testing.
Robin
One thing I do after tightening the jam nut is the rotate both adjuster and jam nut together another 1/8 turn. Makes them a bitch to get apart. However, this is on Cranes and the adjuster is at the pivot point.
I am going to try to stay with my adjustable rockers.
What is the correct amount of preload to put on the rocker/pushrod/lifter?
My rockers are pedestal shaft mount rockers with set screw at the pushrod tip.
I am getting different amounts of advice on how much preload to put into the lifter: Crane is saying .08-.09"
I need to confirm that this is correct???
What is the correct amount of preload to put on the rocker/pushrod/lifter?
My rockers are pedestal shaft mount rockers with set screw at the pushrod tip.
I am getting different amounts of advice on how much preload to put into the lifter: Crane is saying .08-.09"
I need to confirm that this is correct???
TECH Resident
Joined: Aug 2004
Posts: 875
Likes: 2
From: Portland Oregon
I build my motor with Comp adjustable shaft rockers, and after setting the lifters, torqued everything to Comp factory specs. 233/239 .600 with Comp 918 springs. Started the motor, within 3 minutes one of the rocker nuts had backed off until it was hitting the valve cover.
I had to develop my own torque specs to make it work. The specs that came with the rockers were worthless. Now I torque the rocker adjusters nuts to 25lbs with oil on the threads. That's about 2X what the factory spec was. It works for me.
I had to develop my own torque specs to make it work. The specs that came with the rockers were worthless. Now I torque the rocker adjusters nuts to 25lbs with oil on the threads. That's about 2X what the factory spec was. It works for me.
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Are you using an adjustable rocker on hydraulic lifters?
What preload are you putting on the lifter? .05", .06, .08, .09"????
I suspect you (WE) are not putting enough preload on the lifter, and the pushrod is vibrating the adjuster out. Currently Crane is recommending .08-.09" preload onto the lifter plunger, which is way more than I had.
What preload are you putting on the lifter? .05", .06, .08, .09"????
I suspect you (WE) are not putting enough preload on the lifter, and the pushrod is vibrating the adjuster out. Currently Crane is recommending .08-.09" preload onto the lifter plunger, which is way more than I had.
We found that is we lost control of the valvetrain it would loosen everything. On the dyno we could not keep the jam nuts from backing off no matter how we set the valves.
I would check the installed height of the springs as well as the seat pressure. Also talk to the cam vendor about the design of the ramps on the cam. That cam should be a gentle on the valvetrain but one never knows.
I will be back on the spin tron shortly with an LS engine using several hydraulic roller cams. We hope to show some examples of what is happening with that testing.
Robin
I would check the installed height of the springs as well as the seat pressure. Also talk to the cam vendor about the design of the ramps on the cam. That cam should be a gentle on the valvetrain but one never knows.
I will be back on the spin tron shortly with an LS engine using several hydraulic roller cams. We hope to show some examples of what is happening with that testing.
Robin
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Verdad Gallardo I would go with stockers if my engine were crate stock, but it seems to me that stockers are "torque and pray", does not take into account head deck milling, valvesprings and valve heights, cam profile, head gasket thickness, etc.
Did not realize they had adjustable rockers for L92 offset intake...
I build my motor with Comp adjustable shaft rockers, and after setting the lifters, torqued everything to Comp factory specs. 233/239 .600 with Comp 918 springs. Started the motor, within 3 minutes one of the rocker nuts had backed off until it was hitting the valve cover.
I had to develop my own torque specs to make it work. The specs that came with the rockers were worthless. Now I torque the rocker adjusters nuts to 25lbs with oil on the threads. That's about 2X what the factory spec was. It works for me.
I had to develop my own torque specs to make it work. The specs that came with the rockers were worthless. Now I torque the rocker adjusters nuts to 25lbs with oil on the threads. That's about 2X what the factory spec was. It works for me.
It flat out AMAZES me the amount of people that just guess on their pushrod size when they buy their heads and cams. As well as some vendors who sell cookie cutter size pushrods as part of their heads/cam combos. Pushrods should be the last thing you buy about a day before you fire your motor. Trend stocks and sells chrome-moly pushrods in 0.025" increments, so you can get them in a day or two (or same day if you live here in Detroit).
-Geoff
