Roller Rocker STud size
Racer
Joined: Aug 2004
Posts: 377
Likes: 1
From: Redmond Wa
Correction.... I just bought a set of LT4 rocker studs for my L98 from Chris at Superior. They are 7/16 on the head end and 3/8 on the rocker end. I know this has no impact on your question just want to be sure the "record" is correct. 
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Originally Posted by Grace91
Correction.... I just bought a set of LT4 rocker studs for my L98 from Chris at Superior. They are 7/16 on the head end and 3/8 on the rocker end. I know this has no impact on your question just want to be sure the "record" is correct.
All SBC studs are 7/16" on the bottom threads that screw into the head. On production LT4 engines the upper threads were 10mm metric threads. On all production LT1 and other SBC the upper threads were 3/8". The production truck Vortec heads had press in studs that are threaded with 3/8" threads. The LT4 studs as listed in the GMPP catalog are just standard 7/16 x 3/8 studs that are not used with guide plates. The other option is to use the standard big block studs that are 7/16 x 7/16 for additional stability.
Burning Brakes
Joined: Nov 2004
Posts: 1,057
Likes: 0
From: Warren Ohio
Originally Posted by tjwong
On production LT4 engines the upper threads were 10mm metric threads.
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Race Director
Joined: May 2001
Posts: 14,165
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LT1's were 3/8, LT4's were a somewhat proprietary 10mm. The new LT4 heads come with LT4 studs because they figure most people will be putting them on an LT1 and you can't exactly buy the 10mm rockers, the only way to get them is to get them off of an LT4.
