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Old 09-17-2019, 11:02 AM
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Vortec head studs

I have a 350 vortec and had the heads worked on a couple of years ago when studs were installed. I haven't driven the car but in inspecting the heads I find that the machine shop has drilled out the bosses for the rocker studs and installed Helicoils. Are these acceptable or have the heads been ruined.

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Old 09-17-2019, 11:24 AM
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Heli's are stronger than the parent threads because of the increased surface area. That is a correct and quality repair.
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Old 09-17-2019, 11:37 AM
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The shop used studs with 7/16” base threads and are too small for the holes and had to install heli-coils in the stud holes in order to fit the base threads on the studs. That is the usual procedure.

You can buy rocker studs with 1/2” base threads.
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Old 09-18-2019, 11:55 AM
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Quote:
Originally Posted by cgates View Post
I have a 350 vortec and had the heads worked on a couple of years ago when studs were installed. I haven't driven the car but in inspecting the heads I find that the machine shop has drilled out the bosses for the rocker studs and installed Helicoils. Are these acceptable or have the heads been ruined.
This is usually done on aluminum heads to use the Helicoils to both spread the install loads over a larger area of the aluminum and to provide a steel to steel thread contact for the stud. The latter eliminates thread wear on installation and removal of steel studs from the softer aluminum.

The use of the in cast iron would not be necessary unless needed for a repair, or just the way that shop does things; but certainly is not harmful.

Bogie
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Old 09-19-2019, 02:24 PM
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I have. A spare set of double hump heads and will prepare them this winter. I did some research and preliminary measurements and I determined that Mr. Gasket #1076 rocker studs are the ones I will use.

They have a jamming shoulder and are 1.470” stud height, .800” adjustment thread height and have 2.100” total adjustment height. They also have 3/8”-24 adjustment threads and they can use standard rocker arms and “set and forget” rocker arm adjustment nuts for hydraulic lifters. I used those studs in my 1963 Pontiac with 421 HO heads.

No guide plates are required with the Mr. Gasket studs and they have standard SAE adjustment threads. All ARP rocker studs have Perma-Loc interference adjustment threads so you must buy ARP Perma-Loc adjustment nuts.

The Mr. Gasket #1076 studs will fit under my shallow 1962 Chevrolet 327 valve covers without using expensive valve cover spacers.

Last edited by MouseFink; 09-19-2019 at 02:49 PM.
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Old 09-20-2019, 03:15 PM
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There are literally hundreds of different rocker studs for SB Chevrolet heads. I spend an hour sorting them out trying to find the best one to use with stock 327 valve covers.

I found a rocker stud that appears to fit in double hump heads and shallow OE valve covers, without having to use expensive valve cover spacers.

They are Mr. Gasket 1076
They have 3/8”-24 adjustment threads, 7/16-14 bottom threads and the height is 1.470”.
That will be short enough to fit under the OE 327 valve covers without poly locks. I will need to have the shop install a helicoil in the stud holes for the 7/16”-14 bottom threads.

I feel like the OE pressed in studs would be OK with the GM 3863151 (L-79) camshaft. However, I will have some Mr. Gasket screw in studs installed in my 1967 ( casting no. 3890462) double hump heads just to be sure.

I will be using Comp Cams 981-16 valve springs with 105 lb seat pressure at 1.700” and 270 lb open pressure at .447” valve lift. That is not too much load even for stock pressed in studs. Valve springs with more than 120 lb seat pressure and 300 lb open pressure is the limit for 3/8” pressed in studs.
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