Rocker Arm Stud Length Question
Thread Starter
Le Mans Master
Joined: Sep 2004
Posts: 6,018
Likes: 565
From: Conroe Texas
Rocker Arm Stud Length Question
can anyone with stock rocker arm studs in an lt1 or l-98 answer me this? i need to know the length from the tip of the 3/8 - 24 threads to the top of the pushrod quide ( or the bottom of the hex if you have the stud off the engine ). i have a 72' lt-1 that the studs need to be replaced and the length, from above, is 1.59". the arp's that i have in my 89 are 1.77 and are too long to fit my 72 with stock valve covers and poly locks. chevrolet has discontinued this item and i need a replacement. thanks.
Race Director
Joined: Sep 2000
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From: The Top of Utah
That doesn't make sense to me. Is it that the studs that are too long, or that the poly locks hit? The studs don't dictate the height of the rocker arm. It is the push rod length and the valve stem height that locates the rocker. It seems unlikely that a stud, less than 3/16" taller, is going to cause an interference with the valve cover. Try a thicker gasket. Now if the poly locks are new and THEY interfere, THAT is a different issue, and is unrelated to the stud length.
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Thread Starter
Le Mans Master
Joined: Sep 2004
Posts: 6,018
Likes: 565
From: Conroe Texas
ok, i have been using this set of poly locks for years and had no problems until i switched in the arp's, and it is the poly lock that is interfering with the valve cover because the stud is .18 longer than my originals. i use poly's so i don't have to set my valves on the mechanical lifter cam as often. the 'self locking' nuts supplied with new rocker arms just don't cut it
agent 86, it sounds like the stock l-98 stud is the same height as my old lt-1's. thanks for the measure, i guess i'll order a set from gm on monday.
agent 86, it sounds like the stock l-98 stud is the same height as my old lt-1's. thanks for the measure, i guess i'll order a set from gm on monday.
Team Owner
Joined: Jan 2003
Posts: 20,298
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From: Summerland B.C. Canada
I don't see how the stud length is causing your poly locks to interfere with cover. A longer stud merely puts more threads into the poly lock.
I switched to the long arp studs because the stock studs didn't have sufficient thread contact with poly locks due to my roller rockers.
I switched to the long arp studs because the stock studs didn't have sufficient thread contact with poly locks due to my roller rockers.
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
A longer stud doesn't move the nut. The Allen headed lock screw will move upward, inside of the poly lock nut, but only the .180". And unless it was flush with the top of the poly nut, in the first place, the clearance won't be reduced by the .180, if any.
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Thread Starter
Le Mans Master
Joined: Sep 2004
Posts: 6,018
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From: Conroe Texas
Originally Posted by AGENT 86
I don't see how the stud length is causing your poly locks to interfere with cover. A longer stud merely puts more threads into the poly lock.
remember, these are stock 1972 lt-1 aluminum valve covers and they don't have the clearance the c4 aluminum headed valve covers have. i run arp's with my 89 with comp cams magnum 1.6 roller tip rockers, and poly locks, and have no clearance issues.
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Thread Starter
Le Mans Master
Joined: Sep 2004
Posts: 6,018
Likes: 565
From: Conroe Texas
well, i think my problem is solved. the set screw i had in the polys on the 72 were about .1 longer than the set screws in the polys on the 89. seems quite a few years ago i replaced them with stainless set screws. swapped out the set screws and found a pair of moroso blue valve cover gaskets that i had tucked away, got #2 and #8 rockers adjusted ( the set screws stand off the top of the polys by about .04 ) and the valve covers will now bolt down without any interference. finish adjusting all my lifters and i should be good to go.
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Originally Posted by AGENT 86
I don't see how the stud length is causing your poly locks to interfere with cover. A longer stud merely puts more threads into the poly lock.
I switched to the long arp studs because the stock studs didn't have sufficient thread contact with poly locks due to my roller rockers.
I switched to the long arp studs because the stock studs didn't have sufficient thread contact with poly locks due to my roller rockers.
Same here. 1.75" ARP studs were perfect w/ my Pro Mags and provided full thread contact w/o any increase in overall height.
