Valve Lash And Polylocks - Team Camaro Tech
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post #1 of 10 (permalink) Old Oct 1st, 16, 04:27 PM Thread Starter
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Valve Lash And Polylocks

Hey all. I'm setting my valve lash and had a question. I'm currently running Magnum roller tip rockers (1411) with ARP studs and Polylocks. These rockers originally came with pinch nuts, and I didn't care for them. Called Comp Cams and they said these Polylocks (300-8241) were good to go.

I've never used Polylocks, so was unsure as to what to expect. When taking the slack out of the pushrod, I can do that by hand when twisting the Polylock down the stud, and then use my ratchet to turn another 1/2 turn. Then I set the top screw.

Does this sound right? Seemed a bit too 'easy' when twisting the Polylock by hand, but maybe that's the point.

Also, how tight should the top screw be?

Thanks.

67 Black RS Coupe, 383, M21 & 10 Bolt Posi. Edelbrock E-Tech 170 Heads, 2204 Roller Cam, Air Gap Intake.
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post #2 of 10 (permalink) Old Oct 1st, 16, 06:10 PM
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Re: Valve Lash And Polylocks

You have to hold the polylock nut so that it doesn't change the lash while tightening the set screw to snug (about 20 ft. lbs.) There is a special tool to lash the valves with poly locks that makes it very easy to do. The tool utilizes a T-handle Allen (hex) wrench to set the jam nut so as you can see there isn't a lot of torque applied.

You probably will not be able to turn the polylock nut down to set the plunger in the hydraulic lifter because oil is trapped in the side of the lifter body as you compress the piston and once it covers the bleed down hole becomes quite incompressible. But you have the correct idea.

Lash is set hot because the head can expand to take up a lot of your preload if it is made of aluminum.

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post #3 of 10 (permalink) Old Oct 1st, 16, 08:49 PM Thread Starter
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Re: Valve Lash And Polylocks

Thanks Dave. I have a 3/8" hex T-Handle to do the job with. Is the correct procedure to set the lash, then hold the Polylock while adjusting the set screw so that the lash doesn't change? If so, how would I go about getting 20 ft/lbs, is is this just an estimated guess with the T-handle?

I've read that there is a 'click' when the set screw is torqued correctly, but not sure about that.

I've also read that some turn the set screw with the Polylock and tighten that way?

67 Black RS Coupe, 383, M21 & 10 Bolt Posi. Edelbrock E-Tech 170 Heads, 2204 Roller Cam, Air Gap Intake.
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post #4 of 10 (permalink) Old Oct 1st, 16, 10:09 PM
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Re: Valve Lash And Polylocks

The best way to set the lash is to tighten the nut until the slack is taken out by jiggling the pushrod up and down. Then tighten another 1/4-1/2 turn. Then run the set screw down snug and then give the nut a turn just enough to set the set screw.
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post #5 of 10 (permalink) Old Oct 1st, 16, 10:38 PM
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Re: Valve Lash And Polylocks

Quote:
Originally Posted by cv2065 View Post
Hey all. I'm setting my valve lash and had a question. I'm currently running Magnum roller tip rockers (1411) with ARP studs and Polylocks. These rockers originally came with pinch nuts, and I didn't care for them. Called Comp Cams and they said these Polylocks (300-8241) were good to go.

I've never used Polylocks, so was unsure as to what to expect. When taking the slack out of the pushrod, I can do that by hand when twisting the Polylock down the stud, and then use my ratchet to turn another 1/2 turn. Then I set the top screw.

Does this sound right? Seemed a bit too 'easy' when twisting the Polylock by hand, but maybe that's the point.

Also, how tight should the top screw be?

Thanks.
Obviously your setting a hydraulic cam,so sounds about right to me.
After I set the lash as specified by the lifter manufacture which can vary from 1/4 to 1 full turn depending on aluminum or cast iron head. I lock the set screw and give the poly lock a little tug at the same time.
My wrist says that's just about 20lb/ft I guess.

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post #6 of 10 (permalink) Old Oct 2nd, 16, 02:59 PM
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Re: Valve Lash And Polylocks

After much learning, the answer is that the final tightening must be with both nut and lock tightened together

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post #7 of 10 (permalink) Old Oct 2nd, 16, 05:47 PM Thread Starter
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Re: Valve Lash And Polylocks

Thanks for all of the answers. I went ahead and adjusted them all today. VERY simple to do versus those pinch nuts, which really should never be used as they are very hard on the studs, and will gall them if taken off more than once or twice. That said, I took Dave's advice, and set the lash, then with box wrench holding the Polylock in place, I torqued the set screws down to 20 ft/lbs. After I do my initial run, I'll pull the covers and check the torque on the set screw and studs.

Thanks!
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post #8 of 10 (permalink) Old Apr 23rd, 17, 02:22 PM Thread Starter
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Re: Valve Lash And Polylocks

Hey all. Coming back around on this post, as the engine is finally in and today was the first start up. Didn't take long for some tapping sounds under the valve covers, so I'm going to reset the valves.

Initially, I found zero lash on each valve (rotating every 90 degrees in firing order), gave it a half turn, then tightened the set screw to 20 ft/lbs. Doesn't seem like this held, so want to be sure that I'm doing it correctly. If I find zero lash, give it 1/4 turn, set screw to 20 ft/lbs, then turn both the set screw and nut another 1/4 turn, does this seem correct or will i be cracking Polylocks?

67 Black RS Coupe, 383, M21 & 10 Bolt Posi. Edelbrock E-Tech 170 Heads, 2204 Roller Cam, Air Gap Intake.
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post #9 of 10 (permalink) Old Apr 23rd, 17, 03:40 PM
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Re: Valve Lash And Polylocks

Not 1/4 turn at the end,more 1/16 , it does kind of make a snap

69 Copo 9560 ZL-1 automatic [email protected], 1.95 on f70-14 polyglas F.AS.T. Race June 2016
69 Copo 9560 ZL-1 4spd [email protected] 1.93 60ft on F70/14
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post #10 of 10 (permalink) Old Apr 23rd, 17, 05:55 PM Thread Starter
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Re: Valve Lash And Polylocks

Thanks Morgan. So then I'll set lash at almost a half turn after zero lash, then set screw at 20 ft/lbs, then another 1/16 of a turn both screw and polylock.

67 Black RS Coupe, 383, M21 & 10 Bolt Posi. Edelbrock E-Tech 170 Heads, 2204 Roller Cam, Air Gap Intake.
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