sch151

Building a 1990 L98 350...not too fancy but I want NICE. I'm using the original Corvette 113 alum heads and I was wondering if anyone has any input on using 7/16 ARP studs with new roller rockers versus using the stock 3/8 stud. Probably going to use a mild Lunati 'Voodoo' Cam and I've been told 3/8 studs can flex up to 0.50 under loads.

Thanks in advance...

RBob

iTrader: (1)

I used Crane 7/16" studs (# 99157-16), with the Comp Pro Mag roller rockers (# 1304-16).

Also placed a 7/16" grade 8 washer under the stud hex to space it up a hair. This was to prevent the stud from bottoming in the threads ('113 heads).

Changed the guide plates out for a set of hardened early on. Don't have the part number. Note that if stepped plates are used part of the bracing inside the rocker cover needs to be removed. Used hardened pushrods to match.

The rockers I listed are regular style (non self aligning).

As for flex, yes, I was surprised to see the amount of flex in the stock 3/8" studs with the stock '113 over the counter heads with the orange springs. If you need to buy rockers and then longer studs to match, there is every reason to just go with a 7/16" stud.

RBob.

sch151

Thanks for the reply, but I'm confused on one point. What was the reason for using the grade 8 washers under the studs if you were also using guide plates? Are the new 7/16 studs so long that they might bottom out in the head if you don't use plates AND washers. Or, did you first use the washers then took them out when you installed the guide plates? Finally, what is meant by "stepped" plates?

InfernalVortex

iTrader: (4)

I may be wrong, but I'm thinking it's because the pro magnum rockers have such thick trunions that sometimes the rocker nut doesn't get a good bite on the rocker stud threads. He basically wanted the stud to be taller so that the rocker nut would be threaded all the way on when valve lash was set.

I have a similar problem with mine:



See how the locking set screws are sunk in so far? Theyre not as bad as a lot I've seen though.

RBob

iTrader: (1)

The bottom of the stud was a tad too long. With the guide plates the stud would just start to bottom out in the head. So added a washer under each stud. Used both a washer and the guide plate below the hex of the stud.

Could also have ground the lower part of the stud shorter. But the washers were easier. And the extra stud length didn't hurt. Recall that the washers are not that thick. Maybe 3/64" (between a 1/32" and 1/16").

Stepped guide plates are different then the stock flat ones. As they move from the stud portion to the 'guide' portion then are bent (twice) to be closer to the rocker arm. Basically like a set of stairs where there is a 'step up.'

IIRC the guide plates I used are Manley.

Note that if you use self-aligning rockers then the stock pushrods and guide plates can be used. As the stock '113 guide plates are not for guiding the pushrod. They are soft and have a larger slot. Just an assembly aid for the factory engine build.

If you use standard rockers then hardened guide plates and pushrods are required.

RBob.

sch151

Thanks for clearing that up but, unless I'm wrong, I think in your last paragraph you meant to say "stock pushrods and guide plates CAN'T be used". If so, I need to use:
1) self aligning roller rockers and hardened push rods or
2) standard roller rockers, hardened guide plates and hardened push rods

Correct??

Who makes a self aligning roller for 7/16 studs? I didn't see one under Comp Pro Mag...

RBob

iTrader: (1)

For #1 above: when using self aligning rockers, then STOCK pushrods and STOCK guide plates shall be used.

The rocker aligns itself, no need for real guide plates.

#2 above is correct.

RBob.

sch151

After reading your original reply again I realized I was incorrect...thanks again for clearing that up!!

Air_Adam

ProMagnum rockers need a longer than normal stud. I know this from direct experience. I used a stock length stud at first, and there wasn't much thread engagement - and I ended up snapping the top off of a stuf because of that. ARP makes a set that IIRC is something between 1/8" and 1/4" longer than stock. These work perfectly.

Air_Adam

If you are using self-sligning rockers, you don't use ANY guideplates. Just use a washer the same thickness as the guideplate under the stud so it sits at the same height when torqued down to the head.