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#1
07-09-2014, 09:44 PM
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Correct Polylock Length
I just spent the remaining 900 dollars on my 400 and got it just about all buttoned up just to find out that my polylocks are way way to short. They measure .86 inches. I think that they are for full roller rockers. I am using stock stamped rockers with BBC 7/16-20 1.77 tall screw in studs. Everything I see on jegs and summit are for full roller only. If i get in a pinch, could I use stamped nuts for a BBC? What do yall think?
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#2
07-09-2014, 10:03 PM
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ARP makes polylocks specifically for the stamped rocker arm application. I believe their website is www.arp-bolts.com.
__________________
“It takes considerable knowledge just to realize the extent of your own ignorance.” Dr. Thomas Sowell |
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#3
07-10-2014, 03:46 PM
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As an aside ... here is an essential step which is often over-looked. Always make sure the studs have been butt ground flat. This gives the poly locks a nice flat & even surface to tighten against.
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1969 GTO hard top ~ Std bore 400, '70-RA3 block, 670 heads, Bal. & Blue... M22, 12-bolt w/3:55s |
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#4
07-10-2014, 05:21 PM
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Is this a flat tappet cam or roller. Sounds like the rocker studs are to short or the push rods are to long.
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Bull Nose Formula-461, 6x-4, Q-jet, HEI, TH400, 8.5 3.08, superslowjunk |
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#5
07-10-2014, 07:07 PM
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Flat tappet. I just found out that the rocker studs have the wrong thread length. I have to get new rocker studs but I dont know which ones to get. Here is a pic of the difference from the factory one and the one from ARP
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#6
06-29-2019, 07:34 PM
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I have the same question. I have 7/16" studs x 1.75" length installed. Was going to run PRW roller tips with the polylocks supplied by the kit but after learning of quality issues with the rollers want to go back to stamped rockers. What polylocks should be used? The cam (exact one TBD) will be hydraulic flat tappet with no more than about 0.480" lift.
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1970 GTO 400 Atoll Blue, PS, PDB, A/C Was M20 4 speed, now has Keisler RS600 5 speed. |
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#7
06-29-2019, 09:15 PM
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I've used hardened washers between the pivot ball and the polylock, when the polylock was too short. Don't remember the exact size, but it seems it was a metric washer that gave the best fit.
Longer nuts, or shorter studs would be the preferred solution.
__________________
'73 T/A (clone). Low budget stock headed 8.3:1 455, 222/242 116lsa .443/.435 cam. FAST Sportsman EFI, 315rwhp/385rwtq on 87 octane. 13.12 @103.2, 1.91 60'. '67 Firebird [sold], ; 11.27 @ 119.61, 7.167 @ 96.07, with UD 280/280 (108LSA/ 109 ICL)solid cam. [1.537, 7.233 @93.61, 11.46 @ 115.4 w/ old UD 288/296 108 hydraulic cam] Feb '05 HPP, home-ported "16" D-ports, dished pistons (pump gas only), 3.42 gears, 275/60 DR's, 750DP, T2, full exhaust My webpage http://lnlpd.com/home |
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#8
06-29-2019, 09:33 PM
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Quote:
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1970 GTO 400 Atoll Blue, PS, PDB, A/C Was M20 4 speed, now has Keisler RS600 5 speed. |
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#9
06-29-2019, 09:35 PM
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Poly-locks come in several lengths. 1" is a common length. Measuring what you have vs what you need should get you in the ball park.
These are 1.125" long. https://www.summitracing.com/parts/pro-66936/overview/ These are 1.190" long. https://www.summitracing.com/parts/t...04-8/overview/ These are 1.300" long. https://www.summitracing.com/parts/c...3-16/overview/ https://www.amazon.com/Cams-4603-16-.../dp/B000CESFOW https://www.autozone.com/engine/rock...ng-nut/85812_0 If you wanna spend more, here are some 1.200" long ARP brand nuts. https://www.cnc-motorsports.com/arp-...242-50519.html Last edited by ponyakr; 06-29-2019 at 09:57 PM. |
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#10
06-29-2019, 10:38 PM
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Quote:
__________________
1970 GTO 400 Atoll Blue, PS, PDB, A/C Was M20 4 speed, now has Keisler RS600 5 speed. |
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#11
06-30-2019, 01:28 AM
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Just out of curiosity why the obsession with poly locks for non full roller rocker applications. What’s wrong with the good old fashioned pivot ball and nut
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468/TKO600 Ford thru bolt equipped 64 Tempest Custom. Custom Nocturne Blue with black interior. |
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#12
06-30-2019, 03:35 AM
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Several things. The stock Pontiac rocker arm, ball, and bottleneck stud only work with stock base circle cams. The stock Pontiac nut has no locking function other than being jammed down on the bottleneck stud at 20 pounds, and doing that with an aftermarket cam will probably hang the valves open unless you get really lucky. So you need either 3/8" polylocks or Chevy small block 3/8" crimp nuts for the 3/8" threaded studs - or you toss the weaker bottleneck studs for the 7/16" aftermarket stud. Then you either need Chevy BB crimp nuts or polylocks. Crimp nuts should only be one use, so most go with polylocks for unlimited adjustments. The original rocker and ball assembly sits very low on the stud, and in this case the 1.77" stud is too tall for the short polylock to supply any preload, and I suspect that even the longer polylocks still might not be long enough. The 1.77" is already on the short side and going to a readily avalilable 1.75" isn't much shorter.
Bigger problem is the slot in the stock stamped rocker arm might not be sufficient for the new cam's lift. Then you start crunching the valve train with results similar to coil bind.
__________________
Mick Batson 1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 2+2 survivor AC auto -- 1965 Catalina Safari Wagon in progress. |
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#13
06-30-2019, 07:59 AM
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https://www.ebay.com/itm/RAS4-stock-...0AAOSwxYxUrdp2 And these.https://www.ebay.com/itm/Pontiac-sho...ox!28779!US!-1
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#14
06-30-2019, 08:14 AM
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"...I suspect that even the longer polylocks still might not be long enough..."
Just curious. You don't think that even the 1.300" long nuts will be long enuff to work with a 1.77" stud?  https://www.summitracing.com/parts/c...3-16/overview/ https://www.jegs.com/i/Comp+Cams/249...B&gclsrc=aw.ds Last edited by ponyakr; 06-30-2019 at 08:24 AM. |
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#15
06-30-2019, 01:33 PM
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Many of us have ended up using a hardened washer under the longer polylocks after getting oh-so-close to getting proper preload. In round numbers figure that the Allen screw takes up about .300" inch of the 1.300" leaving you 1" of take-up. 1.77" - 1.00" leaves a minimum usable height of .77". If the rocker/ball combination sits a little lower than that, then hardened washers will need to be added.
__________________
Mick Batson 1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 2+2 survivor AC auto -- 1965 Catalina Safari Wagon in progress. |
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#16
06-30-2019, 02:07 PM
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I used arp hardened washers under the nut to get set screw engagement.
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"...ridge reamer and ring compressor? Do they have tools like that?" |
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#17
06-30-2019, 07:18 PM
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Quote:
My current 455 came with Crane Kool Nuts on it. I haven't measured the studs or nuts. But, no washers are needed to adjust the CC roller tip rockers, with the current Summit 2802 cam, or the bigger Lunati that was in it. This shows the nuts to be only 1" long. https://cranecams.com/nut-rocker-arm...-nut-99769-16/ As you can see in the pic, the lock screws are not exactly flush. But, there are plenty of lock screw threads inside the nuts, to lock the nuts & prevent back-off. I could use washers. But they are definitely not needed. Also, 1.300" long nuts would work. But, they are also not needed, on this engine. Just doing a little math, if I used the 1.300" nuts, I could use studs at least .300" longer than I have. So, if I have 1.750" studs, I could switch to 2" studs, 1.300" nuts, & have the lock screws .050" deeper into the nuts. Can't imagine that 1.300" nuts wouldn't work with 1.75" or slightly longer studs, without washers, when using CC Roller tips. So, again, I'd like to know if anybody here has actually used 1.300" nuts, with 1.75" studs, and had to use washers. ??? Last edited by ponyakr; 06-30-2019 at 08:12 PM. |
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#18
06-30-2019, 08:17 PM
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In case anybody needs some new 7/16 studs, thought I'd list a few lengths.
These Jegs are 1.68" long. https://www.jegs.com/i/JEGS/555/20584/10002/-1 These are 1.75" long. https://www.summitracing.com/parts/a...7101/overview/ These are 1.775 long. https://www.jegs.com/i/JEGS/555/20582/10002/-1 These are 1.90" long. https://www.summitracing.com/parts/t...0614/overview/ These are 2" long. https://www.summitracing.com/parts/t...0613/overview/ There are lots of other lengths. But one of these lengths should work with most common Pontiac street applications. Last edited by ponyakr; 06-30-2019 at 08:41 PM. |
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#19
06-30-2019, 10:30 PM
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__________________
A man who falls for everything stands for nothing. |
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#20
07-01-2019, 07:58 AM
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Quote:
Back in the old days, I used the stock bottleneck studs, with Mr. Gasket nuts, & washers when/if needed. Never broke a stud. But I never used really big cam & spring pressures. https://www.summitracing.com/parts/mrg-920g/overview/ Had one set of 7/16 studs, on some RA4 heads I had. Also used Mr. G nuts on these. I remember that the 3/8 nuts were gold colored, & the 7/16 were silver/gray colored. Probably used washers under these nuts. Don't remember. I do remember that I won lots of races with this engine in '78-'79. A guy posted on the Summit site that these nuts were too short for his 455. Said the 1.300" length worked good on his engine. Didn't mention stud length. " I bought and tried these on a 1972 Pontiac 455 with 7/16 screw in rocker studs. These are too short to function as the stud protrudes thru the center of the locking nut, leaving no room to place the Allen nut inside the top of the lock. These are only 0.875 long, a detail that is difficult to locate until you find out they are too short. To function, I had to return these and buy a lock that was 1.2 or 1.3" in overall length. These 924G's are marketed as Chevy/Pontiac locks, and Mr Gasket only offers this length in 7/16" diameter. They don't fit, are a colossal waste of time and its description should be revised. Summit (happily) replaced these with ARP 300-8242 locks which are 1.3 long and actually WORK on Pontiacs with 7/16 rocker studs. These also fit under stock Pontiac valve covers. " Anyhow, looks like both stud & nut length are just 2 of the factors that determine whether a particular nut will work on a particular engine or not. Other factors have been mentioned, including the particular rocker arm used. Don't know how much variation there is between the different types & brands of rockers. I assume it is a considerable amount, since there are so many different lengths of studs & nuts. So, for anyone who don't know what length nut they'll need, I suppose one way to tell is to install rocker & pushrod, and measure the amount of stud left above the rocker. Then add enuff for the lock screw above that. That should provide a minimum ballpark figure, for nut length needed. There's probably a better way. But that's the best I can come up with. 
Last edited by ponyakr; 07-01-2019 at 08:49 AM. |
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