Technical Do I need guide plates on this small block Chevy with roller tip rockers?

I've got a customer's Truck in with a 327 that was supposedly rebuilt at one time and assembled. Everything has been loose that I've touched on this motor and so were the valve covers so I took them off and they had no gaskets so I was going to put some gaskets on them. Upon inspection it's got roller tip rockers and poly locks. The thing is when the valves are closed I can move the rocker about a half inch side to side. This is not normal right? It does have screw in studs. Should it have guide plates? These are 5/16 pushrods

 

Looking at the push rod holes it would need guide plates or self aligning rocker arms.

 

Might find that the heads that don't require guides, have slots instead of holes for the pushrods. The slot keeps the pushrod aligned. With these heads, as mentioned, you need guide plates. Later engines (80s-90s) had rockers with an alignment slot on the rocker tip, but they also had pressed in studs. These heads with screw in studs are designed to be used with guide plates.

 

Should you decide to install guide plates, you will need hardened push rods so they don't wear at the plate contact area.

 

It has hardened pushrods .motor has not been run yet. I don't know if it has a hydraulic or solid cam I'm waiting for the owner to get back to me but it feels like I can push the lifters down a little bit so I'm thinking it's hydraulic. Going to adjust a couple valves and see how it feels as I don't think these were adjusted properly

 

They look like 1967 camel hump 462 heads to me, which were not designed for screw in studs..somebody added them. Adding the guideplates should be easy since they're already converted to screw in studs.

In looking at other 462 heads on the web..id say your pushrod holes are rounder than they should be...allowing too much side to side movement. Check out other similar heads to see what I mean. The normal 462 holes look like a slot with a rounded top and bottom. Your holes look totally round, with a gap on either side of the pushrod. So I would totally add the guideplates..

 

Yes they are the 462 camel humps and yes somebody put screw in studs so I figured they should have put some guide plates in. I pulled the rocker off and checked it with the stock rocker arm and it definitely has more slot in the bottom than the stock one that allows it to move around more. So I may just buy a set of guide plates for it and see how they fit. I've got another 327 here that basically has the same setup on a stand that has guide plates they barely move side to side so I figure that's what needs to be done

 

those heads have been machined for use with guide plates. The stock heads right where the stud would have been pressed in, was kinda rounded at the stud location. the standard practice is it to pull the old press in studs, mill the stud boss flat on the top and then tap for the screw in studs. Once you put the guide plates in, color the valve tip with a dry erase marker and install the rocker and adjust rotate the engine one revolution by hand, this will wear off the dry erase marker on the valve tip and let you check that you have the roller tip centered on the valve tip. then you can adjust ass necessary with either the guide plates or different length push rods.

 

I hate to be the bearer of bad news but in the "Chevrolet small block parts interchange manual", when you add screw-in studs and guide plates to heads that weren't manufactured with them, you must also mill down the rocker stud bosses (p96).

In 1988 the pushrod holes changed from slots to round which means "rail-type" rockers are now required (just like in some low-performance Ford engines) to work with this setup you also needed valves with slightly longer tips, it also mentions Crane manufactured "rail-type" rockers specifically to work with this setup (p94).

I know this isn't what you or the customer wants to hear but to save money and time the lump needs to be pulled and gone over by an experienced engine builder.

Edit; As nailhead jason said it looks like the rocker stands have been milled, still a good idea to check the valvetrain geometry, you may have to change the pushrods depending on which valves were used. Best of luck with your project.

 

Just curious, why does that thing look dry as a chip? It's even got some rust in there. Was any sort of lubricant found inside the thing?

 

This is commonly done when doing screw in studs, these heads have had that done.

 

These are 1967 heads.

 

Wouldn’t the easiest option be SA rockers?

 

The reason it looks dry as a bone as it's never been fired up and also nobody put any Lube on anything it looks like as The Rocker balls tips and anything are dry as hell so who knows what's been done inside or if it's right

 

Sounds like a good reason to do a full teardown and check things over

 

Yep we'll see what the customer has to say and who built it

 

I have a 283 like that as well. Only my problem was the opposite. It was rebuilt then FILLED TO THE TOP with 30w!

 

I wonder what Rookie put that one together.....

 

Years back my neighbor had bought a case of oil. Told his daughter to check the oil an fill it up in something. Said he got home there was only quart or two left. Yep, she filled it up.

 

You can get adjustable guide plates from Alex's Parts , very useful on a SBC , inexpensive as well !

 

Hopefully, whoever milled the rocker stud bosses for the screw in studs, milled them down far enough for the guide plates to be used.

 

A simple priming of the oil pump, and turning the engine by hand should result in oil getting to anywhere it's needed. Prime it to get the pressure up, then stop and turn the engine and prime again until it's got oil at all the rockers.
Hopefully there's some documented info those pushrods are truly hardened if you add guide plates? I wouldn't take someone's word for it, and end up with a real mess if they aren't really hardened.

 

I ended up getting a set of guide plates and hardened push rods for it. Installed everything and everything went as planned. Primed the motor with the drill and turned it over till I got oil coming out of the Rockers. I'm sure it'll be okay but we'll see next week when I fire it off