# Poly Locks on factory rockers



## scoob (Jul 18, 2011)

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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## jetstang (Nov 5, 2008)

I like the poly locks because you can adjust the valves, instead of just torquing the originals to spec. I wouldn't go through the trouble of swapping them out.


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## BearGFR (Aug 25, 2008)

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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## geeteeohguy (Feb 2, 2008)

I've been running them on the stock- headed '65 389 in my '65 GTO.....since 1981 without any issues. Works for me.


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## lars (Sep 28, 2004)

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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## rickm (Feb 8, 2012)

they were also part of the royal bobcat treatment , using the stock pontiac rockers...


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## scoob (Jul 18, 2011)

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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## pontiac (Mar 6, 2011)

no advantage on stock valve train. Factory studs will not match to polylock set screw and will usually loosen.


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## the65gto (Oct 9, 2008)

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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## pontiac (Mar 6, 2011)

show us the stud you use with that poly lock. top of the stud is the critical part.


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## Herding Goats (Sep 16, 2017)

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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## Herding Goats (Sep 16, 2017)

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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## PontiacJim (Dec 29, 2012)

Herding Goats said:


> 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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## Herding Goats (Sep 16, 2017)

PontiacJim said:


> 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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## PontiacJim (Dec 29, 2012)

Herding Goats said:


> 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.










67-72 GTO FIREBIRD CHROME VALVE COVERS DRIPPERS 67-81 Pontiac 400 389 455 | eBay


VALVE COVERS HAVE THE DRIPPERS INSIDE! These new repro valve covers are correct in every way! will fit the Pontiac engines 326-350-389-400-421-428-455 engines from 1967-1982. These covers are sold as a pair.



www.ebay.com


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## Herding Goats (Sep 16, 2017)

PontiacJim said:


> 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!


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## foreevergoat (Oct 24, 2011)

geeteeohguy said:


> 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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## Herding Goats (Sep 16, 2017)

foreevergoat said:


> 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?


Hi foreevergoat, thought I would post an update on my setup with the ARP 135-7101 rocker studs (7/16 stud, 1.75" installed height) with ARP 300-8242 Perma-Loc rocker arm nuts in case it helps you or others. I had to use a bottoming tap on the stud holes as the ARP studs were a little deeper than stock. Using my 490027 Pontiac valve covers with built-in drippers was tight. I had enough height on the poly locks but had some interference on the high side of the cover at the pushrod side of the rocker. Luckily rotating the cover 180 degrees fixed that or I would have had some nice wall ornaments.
More specifically to your question the Perma-Locs I used are for stock, stamped rockers. ARP makes a roller version too. You will need to replace the studs if using these as they are 7/16" and you need that smooth top surface for the lock. If you have press-in studs you will need a different stud.


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