[ReelFun]

I have searched this site for information about converting to screw in studs and the more I search the more confused I get. Here is what I have and want to do. 66 389, 093 heads. I want to convert to screw in studs and add roller rockers with poly locks.I'm running a Melling SPC 7 068 cam. So, do I get 7/16 studs installed and run Comp Cams Magnum Steel Roller tip rocker arms and use poly locks? Or should I just get the 7/16 screw in studs installed and run stamped steel rockers. I don't think that will work with a straight stud will it?

[b-man]

The stud bosses need to be milled down by about .250" and have 7/16-14 Helicoils installed.

Stamped rockers work with straight 7/16" studs. Early Super Duty, RAII and RAIV all used straight 7/16" studs and stamped rockers.

Keep in mind that the rocker balls nest on the 7/16" diameter of the stock bottleneck studs, not on the upper 3/8" portion.

[ponyakr]

Some don't like the Helicoils, but prefer to drill & tap the heads for use with the ARP studs, with 1/2" bottoms.

https://www.summitracing.com/parts/a...Mf9BoCrm3w_wcB

But when using the 7/16 Helicoils, you can use BBC studs in the length you need.

As with many other Pontiac engine parts, opinions differ on the best screw-in stud conversion.

http://www.hotrodders.com/forum/mach...ds-232219.html

Don't know what the price difference would be. Anybody know ?

[SR-71]

Not mine but I my cousin's 64 GTO is running them.

http://www.ebay.com/itm/Pontiac-GTO-...tRuncH&vxp=mtr


They worked as advertised,

[yahooskidoo]

If you want to go studless you can buy these from me and just have the press in studs removed tap the holes and bolt these in. Perfect! http://forums.maxperformanceinc.com/...d.php?t=796420

[b-man]

The $100 ARP conversion studs cost twice what a comparable ARP BBC stud set costs, I paid $48 for the ARP studs I used on my 1964 '716' 389/421 heads.

Going to the 7/16-14 Helicoiled stud threads gives you flexibility on which stud length, with the conversion studs you're pretty much stuck.

The conversion studs also need to have at least 1/8" ground off the bottom, the 1/2-13 threaded end is too long and bottoms out. I know because I used them to convert a set of 1971 #66 455 heads almost 20 years ago in my home garage, they cost about $85 back then.

Pictures of the machine work for screw-in studs done on my '716' heads:

[ReelFun]

Thanks for the information. Now I need to make some decisions. This is basically a stock rebuild, so I want to keep things simple.

[b-man]

My '64 421 HO was also essentially a stock rebuild using an NOS 068 cam. Eliminating the possibility of the stock press-in studs pulling out was a high priority, for the sake of reliability.

[ponyakr]

"...Don't know what the price difference would be. Anybody know ?..."


I realize that there are cheap BBC studs. So, what I am specifically asking is what is the cost of the Helicoils + machining & labor, vs the cost of labor to install the 1/2" bottom studs. Wouldn't hurt to add in the cost of having the base of the big studs shortened, as needed, tho I suppose some guys could take their time and do that themselves.

I assume some of you machine shop guys have done both these jobs a few times. So, give us an aprox $ comparison, please. Because if the Helicoils + labor runs $150 or more, that might influence someone's decision.

And for you guys who have paid to have either method done on a set of heads, please tell us what it cost.

[b-man]

Machine work - cut bosses down .250" and tap for 7/16" Helicoils - $179

Install Helicoils - $20

16 ea. 7/16-14 Helicoils - $16

No matter which stud type you choose it's pretty much a wash, with the conversion studs likely costing more due to the higher cost of the studs themselves along with the additional labor cost to shorten the bottom threaded portion.

Even if you decided to grind off the bottom of the conversion studs yourself (I did with mine) the higher cost of the conversion studs still ends up making them a more expensive way to do it. With either type of stud you're still paying for the boss milling and tapping.

Keep in mind that only the early heads that were not factory equipped with pushrod guide plates will need the stud bosses milled, this added cost will not be incurred when converting the later style heads.

[ReelFun]

B-Man, are these the ones you used on your 421 build?

https://www.summitracing.com/parts/a...7101/overview/

[b-man]

The machine shop supplied the studs, part number listed was 101-7101 so I suspect that they're the same as the ones you've linked to with part number 135-7101.

[Squidward]

Originally Posted by ponyakr

Some don't like the Helicoils, but prefer to drill & tap the heads for use with the ARP studs, with 1/2" bottoms.

https://www.summitracing.com/parts/a...Mf9BoCrm3w_wcB

But when using the 7/16 Helicoils, you can use BBC studs in the length you need.

As with many other Pontiac engine parts, opinions differ on the best screw-in stud conversion.

http://www.hotrodders.com/forum/mach...ds-232219.html

Don't know what the price difference would be. Anybody know ?

Having done both, the helicoils are a bigger PITA. Using a hand drill to get the right hole size for the 7/16 helicoils is not as "self guiding" as one might think.

I WAAAY preferred to do the 290-7201 (?) 1/2-13 bottom studs. No drilling needed, but it is best to use some sort of guide to make sure the tap goes in straight.

I've only done this to later heads, tho, where the stud bosses were already milled flat from the factory.

[63Banshee]

Originally Posted by b-man

The machine shop supplied the studs, part number listed was 101-7101 so I suspect that they're the same as the ones you've linked to with part number 135-7101.

Kit #: 135-7101
Specifications
Installed Height
1.750˝
Adjuster Thread Length
0.850˝
Adjuster Diameter-Pitch
7/16-20
Screw-in Depth
0.800˝
Screw-in Diameter-Pitch
7/16-14
Jobber Price*: $62.72


Kit #: 100-7101
Specifications
Installed Height
1.900˝
Adjuster Thread Length
1.000˝
Adjuster Diameter-Pitch
7/16-20
Screw-in Depth
0.750˝
Screw-in Diameter-Pitch
7/16-14
Jobber Price*: $56.1


No 101-1701 part number currently on the ARP site.

[GRX]

Having performed both on early and later heads, I am with b-man on this one. The helicoils will be just fine. Stronger than many think. And I would never do this operation with hand drill.

[hurryinhoosier62]

Originally Posted by GRX

Having performed both on early and later heads, I am with b-man on this one. The helicoils will be just fine. Stronger than many think. And I would never do this operation with hand drill.

X 2! This operation should only be attempted on a QUALITY drill press or a Bridgeport type mill. Personally, I prefer Time Serts over Helicoils.

[Will]

I had my 061 heads converted to screw-in studs by Dave at SD.

At the time he told me it would be cheaper to go with the conversion (1/2" base) studs, even though the studs are more expensive and have to have a little ground off the base threads. He said the cost of the helicoils and the labor to install them would more than offset the cost of the more expensive studs and minimal labor grinding them down.

I understand that this may not work the same way at all shops and that was quite awhile ago so if prices have changed dramatically that could change the math too.

Just letting you know how it worked out for me. If I was doing it myself I'd probably helicoil them as I don't charge myself that much for labor. ;-)