When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
i been in the process getting a new rebuild running, olds 400, i adjusted the preload per crane cams roller lifters, been sitting 2 weeks and went out to the shop to prime the engine and noticed 2 broken poly locks. crane says 1 1/4 - 1 1/2 turns then lock them down..what happened?
I've only ever heard of 1/4- 1/2 turn past zero lash on hydraulic lifters. Either you misread, the instructions are wrong, or there's some new "technology".
Polylocks are tricky to adjust. It took me awhile to realize that the allen screw is a stop and not the lock. It's fun when you're dealing in thousandths on a solid lifter.
A few things come to mind:
1) That is way too much preload
2) Do you have the correct length studs? How much of the set screw is above/below the top of the poly lock?
3) Are you overtightening them? They don't need to be cranked on like a head bolt.
Post pics to help us better understand what's going on.
I've only ever heard of 1/4- 1/2 turn past zero lash on hydraulic lifters. Either you misread, the instructions are wrong, or there's some new "technology".
Polylocks are tricky to adjust. It took me awhile to realize that the allen screw is a stop and not the lock. It's fun when you're dealing in thousandths on a solid lifter.
I think he is talking about setting the poly locks before start up. You are referring to setting the valve lash after valve clatter stopped on a running engine. The amount of turns after zero lash varies from person to person.
Personally, I set them at 1/8 to 1/4 turn, max. And I use internal snap rings in the lifters instead of the frail hairpins.
I think he is talking about setting the poly locks before start up. You are referring to setting the valve lash after valve clatter stopped on a running engine. The amount of turns after zero lash varies from person to person.
Personally, I set them at 1/8 to 1/4 turn, max. And I use internal snap rings in the lifters instead of the frail hairpins.
The lifter instructions tell you what the manufacturer recommends for preload.
The setup is the same regardless of "starting point". Use the EO/IC method, go to zero lash, then add recommended preload.
Last edited by fleming442; February 28th, 2024 at 11:03 AM.
The lifter instructions tell you what the manufacturer recommends for preload.
The setup is the same regardless of "starting point". Use the EO/IC method, go to zero lash, then add recommended preload.
Yes, manufacturers recommend the amount of preload. Hydraulic lifter preload is done more accurately after the engine has been started and is running. The problem with the OP is broken polylocks before starting the engine.
I've only ever heard of 1/4- 1/2 turn past zero lash on hydraulic lifters. Either you misread, the instructions are wrong, or there's some new "technology".
Polylocks are tricky to adjust. It took me awhile to realize that the allen screw is a stop and not the lock. It's fun when you're dealing in thousandths on a solid lifter.
I just re-read the instructions, it says " up to" 1 1/4-1 1/2 Can be used due to the strength of these lifters....I'm dumber as I get older..
Last edited by 6844268; February 28th, 2024 at 03:14 PM.
The lifter instructions tell you what the manufacturer recommends for preload.
The setup is the same regardless of "starting point". Use the EO/IC method, go to zero lash, then add recommended preload.
After zero lash they should be 1/2 - 3/4 turn then lock down. I misread my info.
A few things come to mind:
1) That is way too much preload
2) Do you have the correct length studs? How much of the set screw is above/below the top of the poly lock?
3) Are you overtightening them? They don't need to be cranked on like a head bolt.
Post pics to help us better understand what's going on.
U are correct on number 1. I read my instructions wrong
Strength has nothing to do with it. It’s the valving and ultimately the amount of available travel in the lifter. I’d start at 3/4 or so and go from there.
Just want to add a vote to what Chad said in reply #3. Broken polylocks have nothing to do with lifter preload. Can you post a picture of where the Polylock broke ? You need to figure out why they broke. I usually crank down on them pretty good and have never had one break.
Just want to add a vote to what Chad said in reply #3. Broken polylocks have nothing to do with lifter preload. Can you post a picture of where the Polylock broke ? You need to figure out why they broke. I usually crank down on them pretty good and have never had one break.
this is the area where my pushrods are binding, pic isnt mine, my builder put on comp rollers 17044-16, 1.6, my heads are edelbrock performer rpm 61025, 3/8 pushrods. i was told these rockers are not for these heads? harland sharp makes a set for these heads. s5003. thoughts?
this is the area where my pushrods are binding, pic isnt mine, my builder put on comp rollers 17044-16, 1.6, my heads are edelbrock performer rpm 61025, 3/8 pushrods. i was told these rockers are not for these heads? harland sharp makes a set for these heads. s5003. thoughts?
this is where 3/8” P rods actually interfere with the body on the comp rockers..not up by the cup as shown in the pic. You’ll need 3/8” long taper P rods to work with the comps. you probably have standard taper P rods. Or you can grind the body of the rocker to clear the P rods you have now
The area of the black marker dot is where you need to clearance them.
when you initially did your 1 1/2 turns, at what point did you establish zero before doing the 1 1/2 turns?
Another thing. To me that pic of the blue rocker isn’t a fulcrum style adjustment.. it’s a P rod cup style adjustment and the adjuster is way to far up in the body which could be why there was contact on that one? The P rods could have been to long to start with
this is where 3/8” P rods actually interfere with the body on the comp rockers..not up by the cup as shown in the pic. You’ll need 3/8” long taper P rods to work with the comps. you probably have standard taper P rods. Or you can grind the body of the rocker to clear the P rods you have now
The area of the black marker dot is where you need to clearance them. backed out the set screws, 1/4 turn on the crank, and check them all, did this for 2 full revolutions then incorrectly gave them the 1 1/4-1 1/2 turns locked them down. So with the binding and over tightening the polys some broke. Should have done 1/2-3/4 turn...I might try to grind them for clearance
when you initially did your 1 1/2 turns, at what point did you establish zero before doing the 1 1/2 turns?
yikes..I can’t even understand your explanation of how you did it wrong.
don’t make sense. If you actually turned the adjuster nut down 1 1/2 turns from zero lash, before even priming them, that shouldn’t bust an adjuster. The lifter plunger would just bottom out when rotating the cam.
it’s different if they were primed and pumped up, then you added the 1 1/2 turns….that may have caused valve spring bind when rotating the engine, and in turn, locked up the valve train and broke the adjuster
but they weren’t primed, correct?
are they short travel hyd roller lifters? What’s the lifter part#?
Last edited by CANADIANOLDS; March 30th, 2024 at 10:05 AM.
yikes..I can’t even understand your explanation of how you did it wrong.
don’t make sense. If you actually turned the adjuster nut down 1 1/2 turns from zero lash, before even priming them, that shouldn’t bust an adjuster. The lifter plunger would just bottom out when rotating the cam.
it’s different if they were primed and pumped up, then you added the 1 1/2 turns….that may have caused valve spring bind when rotating the engine, and in turn, locked up the valve train and broke the adjuster
but they weren’t primed, correct?
are they short travel hyd roller lifters? What’s the lifter part#?
February 28th, 2024, 02:07 AM
