I'm having my vortec heads drilled and tapped for screw in studs and guide plates. The machine shop that I always use needs to know how much to mill the bosses down to before they are tapped. They are very reputable and have done this same thing on other heads. I can't figure out why they are asking this. I told them I would find out and would get back to them on Monday. Are the bosses a different height on the vortecs?

 

if they don't know i think i'd be looking for another shop. you should be able to measure one of the studs you pulled aginst a screw in stud and figure it out. i've never done vortecs but on all the heads i have done i take .4 off if i'm using guide plates and .425 or .45 if i'm not.

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ICON Motorsports

1st & 3rd

 

That is what I was thinking, too. Thanks.

 

94,

The radius and hex collar on Mr. Gasket and ARP studs (hex-type) is about 0.375" under the thread. GMPP studs (P/N 12371058) are 0.325" to the shoulder. Add to that the thickness of the guide, plates, and you should have the depth measurement.

If your studs are different, measure the height under the thread to the mounting surface, and go from there.

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Later,
Vader
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"No matter how hard you try you can't stop us now..."
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even if you are not using guide plates, i would mill them down enough for them and put washers of approx. thickness of a guide plate under the stud. you never know when you might want guide plates.
yeah, if the machine shop didn't know how much in the first place, i would definately go somewhere else. milling down isn't precision science here, it is more commmon sense then anything.