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Old 06-06-2012, 02:47 PM
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Required machining for guide plates

Today I took possession of a pair of 462 fuelie heads & will be having them machined to accept arp screw in rocker studs & guide plates, however I am slightly uncertain on a couple of aspects. which I expect I will need to clarify to the machine shop.

1: I know the bosses will need to be machined down by the thickness of the guide plates but do i need to allow for the hex head on the new studs as well?

2:With regards to enlarging the push-rod slots on the heads what size is recommended for 1.52 roller tip rockers? comp cams says run a 1/2 drill bit through them, but that seems to big & looks as if it will eat through the wall of the inlet track.

3: am I right in presuming the holes should be drilled from a central point on the push-rod slot?

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Old 06-06-2012, 03:31 PM
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I do the PR holes on the mill by plunging a 1/2" end mill through the slot taking only a minimal amount off the intake port outer surface.

Mill the bosses down .325"
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Old 06-06-2012, 03:33 PM
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Dude, how radical is this engine? You don't need screw in rocker studs except for radical cams. You want extra piece of mind? Have them pinned.
Guide plates? Not necessary. Enlarging the pushrod holes for 1.52 rockers? Highly doubtful it will be needed. Mock the heads on the engine and (highly unlikely). Take a grinder and clearance as needed. You are bound and determined to needlessly spend a lot of money.
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Old 06-06-2012, 04:06 PM
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Another option, the one I often do, is to run shoulderless screw in studs wo guideplates. You can tap the stud bosses yourself if you're careful and it saves a lot of money while providing stronger rocker studs.

Pinning is also done by a lot of people but IMO is actually more of a PITA to do and is weaker than screw in studs. But many people do it and it works out just fine.

If the slots machined in the head do no give you proper alignment you can carefully open them up. If you still cannot get proper alignment you can "hog them out" and run self aligning rockers.

What cam are you looking at? How agressive your build is will help determine how far you should go into this. With those old stock heads I'm guessing its a fairly mild build
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Old 06-06-2012, 04:27 PM
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to answer all your questions best i can , ill be fitting screw in studs & guide plates as there sat on coffe table so i plan on using them & I like the peace of mind it provides, also currently one of the press rocker studs has shifted upwards.

also sat on my coffe table is a new set of comp cams magnum roller tip rockers.
part no: 1412-16 "non self aligning" so again they`r guna get used.

as far as ive always understood ya got to use guide plates with those rockers.

as for cam its summits part no: 1785 which is the elgin copy of cranes 274h06 cam, so 218/218 450/450

so with rockers its gunna be around the 455 lift mark.

the above parts were purchased to use with a set of alloy heads that i had, but they werent up to scratch hence the fuelies being fitted.
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Old 06-06-2012, 04:47 PM
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Well the shop should be able to help you out, its a common procedure.

FWIW stock rockers would have been no worse off and would have saved you about $400 by the time you're done.
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