RHS LAX head, valve train question

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popinsmoke

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First I let me thank anyone who responds in advance, I am chasing my tail, I thought I has some things figured out and turns out perhaps not.

I have a fresh 408 short block sitting in the garage looking for a home. I also have some bare RHS LAX heads.

Awhile back I picked up some 8mm stem 1.92 intake and 1.62 exhaust valves.

My understanding those are the valves the heads are set up for?

The head is a hybrid of the the LA style head and the Magnum head?

I have a complete XE268 Cam kit with springs 901, retainers, seals, locks etc but it all says it for 3/8 valves.

Seems like the timing set, cam and lifters are the only things I am going to be able to use from the cam kit.

I have a set of 596 heads that I can use the rest on for a 360 in another car.

The local shops are not being very helpful as it's a chevy shop and they seem to be confused about what to run I lost all confidence when they ask if the head was for "a big block or a small block", I've called indy as RHS no longer deals with the head and all I could get from indy was "send em to me I'll set em up right." which would be great but the shipping would be murder.

The obvious solution is to run the springs,retainers,locks and seals for 5/16 valves as that is the same as 8mm correct? I am wondering if I am missing something or just over thinking it?

What valvetrain are any of you running on theses lax heads? The cam specs are pretty mild for a 408 but it going in a daily driver that's heavy 3800lbs. 224/230 @.50 and .477/.480 lift on a 110 centerline.

Thanks for taking the time to read this post.
 
8mm valve stems don't fit properly in 5/16 guide. .3149 vs .3125

You are dealing in thousandth with guide clearance

Maybe call Brian at IMM. He sets a lot of these heads up and may be able to help you get the right combo of parts.
 

I believe the 8 mm and 1.92 intake and ex valve is correct for lax heads out of the box. I had my intake cut to 2.02 intake by Indy and I mildly cleaned them up an installed Hughes roller rockers shaft mount. Hope this helps.
 
Hughes has the correct spring retainers and locks so you can use the 901 Comp springs. They also increase guide to retainer clearance quite a bit. I would bet there are other members here who can set you up with them or something like them also. IQ52, MRL and MagnumMopar come to mind.
 
The good folks at hughes engines were able to help me out, and the correct parts are on their way.
 
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