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Discussion Starter · #1 ·
I saw a post on a sight that stated that you should not run poly locks with factory rockers ( 1966 heads ) because of a fitment problem . Had engine work done and the shop put poly locks on the rockers and I have at least 1 bad lifter ( new ) going to replace my lifters and want to know if i should also switch back to factory style nuts on my rockers?
 

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Don't believe everything you read on the inter-tubes --- even here :)

Perhaps someone else might have had a fitment problem. That doesn't mean you will. As long as they aren't rubbing anywhere and fit under your valve covers, you're good to go. I like them better than the factory nuts.

Bear
 

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The fitment issues with PolyLocks are as follows:

1. The stock rocker arm splash shields used on post-67 400's cannot be used with PolyLocks.
2. If you don't get the PolyLocks intended for use with the stock Pontiac Bottleneck studs (these PolyLocks have a counterbore below the threaded portion to allow the bottom of the PolyLock to slide over the fatter part of the bottleneck studs), the PolyLock simply won't work: It will bottom out on the bottleneck just like a regular Pontiac rocker nut, and you don't get any adjustment.

If you get the correct counterbored PolyLocks for the bottleneck studs, and if you don't mind losing your splash shields, the PolyLocks work great.

Lars
 

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Discussion Starter · #7 ·
Murphy's Law :::: If anything can go wrong, it will... should be dedicated to my goat. Thanks for the info it really helps a lot
 

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This is what I have been using for the last 40+ years. With the engine hot and running, I loosened the nut until it starts to clatter, then tighten nut almost 1/2 turn, then snug up the jam nut and continue until half turn and nut is tight. Let it cool down, spray with gunk to remove the oil :lol:, water off, install new gaskets/cover.
 

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Hi all, Reviving this thread to see what the options and opinions are in 2021! I want to install ARP 7/16" studs in #64 heads for an adjustable valvetrain with a hydraulic roller cam. I cannot use a valve cover spacer as the air conditioning bracket clearance is tight, but I can do a thicker gasket. Most sources are telling me "maybe". Are the splash guards necessary? Can I fit poly locks on there with the factory (1970) valve covers and stamped rockers? Would love to know what specific brand/part # you guys use for the locks and /or studs.
 

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Thought I would post what I came up with. Going to use ARP 135-7101 rocker studs (7/16 stud, 1.75" installed height) with ARP 300-8242 Perma-Loc rocker arm nuts (for stamped steel rockers). This combo easily clears the stock valve covers, but as noted elsewhere the drippers will not fit. My builder said the drippers are not necessary with the taller poly locks.
 

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Thought I would post what I came up with. Going to use ARP 135-7101 rocker studs (7/16 stud, 1.75" installed height) with ARP 300-8242 Perma-Loc rocker arm nuts (for stamped steel rockers). This combo easily clears the stock valve covers, but as noted elsewhere the drippers will not fit. My builder said the drippers are not necessary with the taller poly locks.
Good update with ARP numbers. I have not looked at, but I thought about the poly-loc's being taller and would get in the way of the oil that spurts out the rocker arms and direct it right back down onto the rocker arm cup. Pontiac also used the drippers that were spot welded to the tops of the valve covers.
 

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Good update with ARP numbers. I have not looked at, but I thought about the poly-loc's being taller and would get in the way of the oil that spurts out the rocker arms and direct it right back down onto the rocker arm cup. Pontiac also used the drippers that were spot welded to the tops of the valve covers.
Thanks Jim, great tip! My original 1970 covers w/o drippers clear the ARP setup with no gasket installed so I may be able to get the covers w/ drippers to clear. I would feel better with the drippers in there. I will get my hands on some and report back.
 

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Thanks Jim, great tip! My original 1970 covers w/o drippers clear the ARP setup with no gasket installed so I may be able to get the covers w/ drippers to clear. I would feel better with the drippers in there. I will get my hands on some and report back.
Here is a new set on Ebay just to show your what they look like. Actually not a bad price if the chrome is done well.


 

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Here is a new set on Ebay just to show your what they look like. Actually not a bad price if the chrome is done well.


Thanks Jim, that does look like a good value. I picked up a set of used ‘73 plus covers, part number 490027. They clear the poly locks even without a gasket in place. Those repros might even offer slightly more clearance without the full interior baffle. I just could not bring myself to replace the originals with a repro, though the used ones and chroming will cost more. Thanks again for the idea on the later covers. Seems like a perfect match!
Motor vehicle Automotive lighting Hood Bumper Automotive exterior
 

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I've been running them on the stock- headed '65 389 in my '65 GTO.....since 1981 without any issues. Works for me.
Hi geeteeohguy, had a problem with broken pushrods in my 65 gto I am going to replace all pushrods and add poly locks and adjust valves can you tell me what poly locks you use it would save me a lit of time researching on the

net? Never had a problem with broken pushrods before any ideas what would cause this?
 
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