roller rockers/studs

Hi ALL, I received my roller rockers for 3/8" studs. Then realized my studs are in fact 3/8" measured at the pressed in portion and on the threaded portion the studs only measure 5/16" (in fact they are 5/16"-24). The rollers of course come with 3/8" locking nuts which are too big to screw on tight! What does one have to do to make this work? Thanks for any advice!

Convert to 3/8" screw in studs. Chuck

Convert to 3/8" screw in studs. Chuck

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+1

Yep. Convert to 3/8

Are there any 5/16" locking nuts? How do I convert to 3/8" studs? How much is involved in doing that? Machine shop involvement? Thanks!

You can not use 3/8" trunion rocker on a 5/16" stud. The conversion is best done by a machine shop that can accurately drill and tap the heads. Chuck

Are the threads in the head stock?? They make kits so you don't have to machine the heads. They are not designed for high hp or a lot of spring pressure, but in your average build will hold up fine. I believe something like this.... https://www.summitracing.com/parts/crn-36655-16/overview/make/ford

Yes the threads are stock. What are trunion rockers? Someone talked me into buying these. I think there's too much involved I'm going back to my old regular rockers. Thanks for the replies but never mind. I was going to install my engine in a few weeks anyway.

The trunion is the center pivot points. Chuck

A trunnion is the round portion of the rocker arm that the stud goes through and serves as the pivot.

Are your rocker arm studs screwed in or pressed in? I ask because in your first post you say they measure 3/8" at the pressed in portion.

Chuck, yes they are pressed in and measure 3/8" on the non threaded portion, but only 5/16" on the threaded portion. I was looking at Summit and found 5/16" locking poly locks but in the description it says not for roller rockers...the 5/16"locking poly locks from Summit look the same as the 3/8" locking poly locks my new roller rockers from Speedway came with and I don't see why the 5/16" locking poly locks from Summit wouldn't work. I have to give Summit a call. Thanks All!

The hole in your trunion is for a 3/8" bolt or stud. Using the rockers on 5/16" studs will allow the rockers to move around on the studs, meaning difficult to keep centered and keep the right contact pattern on the top of the valve stem. You've spent a lot of time and money on your engine, why take a chance on incorrectly matched parts? In my opinion it's not a matter of if they will fail, but how soon.

Pressed in studs are not suitable for any performance modifications, especially valve spring upgrades.

Don, you make a lot of sense! I'm just wondering why the guy who built my engine didn't mention that. So now I'm thinking to give him a call or even a visit. He's supposedly the best guy in town.

Don, you make a lot of sense! I'm just wondering why the guy who built my engine didn't mention that. So now I'm thinking to give him a call or even a visit. He's supposedly the best guy in town.

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If you told him you wanted a performance build and wanted to use roller rockers he should have informed you of what was required. Maybe he's not "the best guy in town". As information, you should establish optimal rocker arm geometry. This is most often accomplished by determining optimal pushrod lengths and buying custom length pushrods. The stock pushrods are not strong enough for any performance build anyway. Chuck

He may be the best guy in town, but if everyone else is crap, it doesn't take much to be on the top of the heap...

So I am one step closer to getting the engine installed, found a set of 5/16" poly lock nuts and I will be using my stock rockers! Now I'm just waiting on 2 car buddies to show/help me on how to adjust the rockers.

So I am one step closer to getting the engine installed, found a set of 5/16" poly lock nuts and I will be using my stock rockers! Now I'm just waiting on 2 car buddies to show/help me on how to adjust the rockers.

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Leave the intake off so you can observe movement and twist the push rods when you set 'zero lash'.  Much easier.

Yeah, about that...engine is already closed up other than valve covers and Dizzy.