Polylocks And Valve Covers
Thread Starter
Staging Lane
Joined: May 2016
Posts: 91
Likes: 2
From: Rochester, NY
Polylocks And Valve Covers Hello everyone!
I’ll try to keep this as simple as possible. I am running a hotcam with the 1.6rr and polylocks that came in the kit. Long story short, a few of the polylocks that came with the GMPP kit became unusable and I was able to get a set of 16 new locks for free due to an error on Summit’s part (I believe they are Crower CRO-86051-16). The locks fit in the valley of the rocker arm just fine, but they’re just tall enough that they rub right up against the valve cover. I wouldn’t be too concerned about this, but one of my poly locks came loose after about 1000 miles and I’m thinking the taller locks aren’t letting the covers seat correctly.
So here’s my dilemma: should I order taller valve covers or should I try to find replacement polylocks? I’ve searched a ton of places and can’t seem to find a GM part number (Edit: just found the GMPP part number from my previous research—19210730) that’s a direct replacement for the locks that came with the hot cam kit. If I should pick up taller covers, which ones should I look at? I have a stock alt in the stock location on my 94 f-body, over-the-valve cover wires, and not a ton of extra cash kicking around.
I think I’d prefer to find the right polylocks—I think that would be the cheapest solution. They apparently ship right from GM, though, and won’t ship out for another week at the very earliest. But what does everyone think?
Thanks in advance!
I’ll try to keep this as simple as possible. I am running a hotcam with the 1.6rr and polylocks that came in the kit. Long story short, a few of the polylocks that came with the GMPP kit became unusable and I was able to get a set of 16 new locks for free due to an error on Summit’s part (I believe they are Crower CRO-86051-16). The locks fit in the valley of the rocker arm just fine, but they’re just tall enough that they rub right up against the valve cover. I wouldn’t be too concerned about this, but one of my poly locks came loose after about 1000 miles and I’m thinking the taller locks aren’t letting the covers seat correctly.
So here’s my dilemma: should I order taller valve covers or should I try to find replacement polylocks? I’ve searched a ton of places and can’t seem to find a GM part number (Edit: just found the GMPP part number from my previous research—19210730) that’s a direct replacement for the locks that came with the hot cam kit. If I should pick up taller covers, which ones should I look at? I have a stock alt in the stock location on my 94 f-body, over-the-valve cover wires, and not a ton of extra cash kicking around.
I think I’d prefer to find the right polylocks—I think that would be the cheapest solution. They apparently ship right from GM, though, and won’t ship out for another week at the very earliest. But what does everyone think?
Thanks in advance!
Last edited by CaptainArbitrage; Aug 6, 2018 at 09:02 AM.
Thread Starter
Staging Lane
Joined: May 2016
Posts: 91
Likes: 2
From: Rochester, NY
I also haven’t trimmed the insides of the stock valve covers.
TECH Veteran
Joined: Apr 2008
Posts: 4,985
Likes: 112
if they are GMPP RR those were made by Crane. Those 1:6 RR should be the "narrow body" ones which do not require any baffle trimming on the VC. Might want to look up poly for a Crane Gold "narrow body" RR to see if they are cheaper and more available than the GMPP ones
As far as the Crowers poly locks being to tall, IDK but if you have a witness mark on inside top of VC they are
I assume the trunnion of the RR is sitting with the "flat" side up....
As far as the Crowers poly locks being to tall, IDK but if you have a witness mark on inside top of VC they are
I assume the trunnion of the RR is sitting with the "flat" side up....
I had a set of the GMPP rockers on my former '96 Z/28, and had no clearance issues with the OE valve covers. FWIW, ARP makes two different polylocks, and if I remember correctly, the difference between them is their "installed height" above the trunnion of the rocker arm.
Thread Starter
Staging Lane
Joined: May 2016
Posts: 91
Likes: 2
From: Rochester, NY
Thank you for the input everyone!
Yes, the trunion on the rocker is flat side up. This was my first engine assembly and that was one of the lessons that I learned along the way.
At this point, I am going to assume that the Crower locks are alright--they are only marginally taller than the GMPP ones. When I put my hand on the valve covers while the engine is running, I don't feel any vibration coming through like I can when a rocker or lock is loose. I've made several mistakes when assembling this engine that resulted in the polylocks or rocker arms getting loose-- this is likely what caused the witness marks.
It's also possible that the one polylock that came loose after 1000 miles was a result of the pushrods being too long (used stock when it turned out that I needed 7.050" IIRC).
For now, I'll stick with everything that I have. If I run into other issues, I'll come back to the drawing board.
Thanks again!
Yes, the trunion on the rocker is flat side up. This was my first engine assembly and that was one of the lessons that I learned along the way.
At this point, I am going to assume that the Crower locks are alright--they are only marginally taller than the GMPP ones. When I put my hand on the valve covers while the engine is running, I don't feel any vibration coming through like I can when a rocker or lock is loose. I've made several mistakes when assembling this engine that resulted in the polylocks or rocker arms getting loose-- this is likely what caused the witness marks.
It's also possible that the one polylock that came loose after 1000 miles was a result of the pushrods being too long (used stock when it turned out that I needed 7.050" IIRC).
For now, I'll stick with everything that I have. If I run into other issues, I'll come back to the drawing board.
Thanks again!