Lapping Rocker Arms

[jeff swisher]

What grit and what compound do you guys use to do this.
Diamond paste or Aluminum Oxide or Silicone carbide?

All my stamped steel rockers are short slot factory stock and I have noticed marks on my studs with .480" lift cams.
So I bought some some extra long slot stamped rockers and the slot was .100" longer.

I placed a pivot ball into a few of them and there is a gap at the rear looking through the stud hole where daylight comes through.
Just holding ball and rocker in my hand.
These things are going to wear in and that means fine metal particles.
I thought about taking a permanent marker and coloring the hole the ball sits in and see where it is contacting before and after.

I thought 600 grit lapping compound for a finish grit should work for lapping in the rocker balls to the arms.

I just want some input from others who have done it . Thanks.

Another thing is grooved pivot balls allowing oil to drain out of the rocker body.
That gap at the rear of the cup would do the same thing with smooth balls.
I plan on running the smooth balls.

[jeff swisher]

I will see if I can load a picture of a stock rocker lapped and on the left a new rocker that I lapped with what I had.
The contact area on the old rocker is all the way around and I took a black Sharpie and colored the new rocker and then lapped
it and you can see the minimal contact area.
This was after a minute with coarse and fine lapping compound..the contact was less than 1/2 of what you see now.

031.JPG

[F-BIRD'88]

This is another reason to run the engine for quite a while /miles- hours- using low spring seat and open force to allow the rockers and balls to seat in. It takes a while.
More than 20-30 minutes running.
i use stock oem old sbc valve springs installed at maxxed install height. 1.77"+++ for "break in"
Then change out for the required racing valve springs.

For my typical Less than .560" net valve lift flat tappet and stamped type rockers budget engines
This is also why I add my Moly anti wear additive to my oil . MolySlip E Oil Supplement.
Let us know what lapping compound material you find is best. Speed and lapped finish.
Might be interesting to A-B the running rocker arm temperature when out of the box VS when hand lapped in as you do., using say a laser temp gun.
Less running heat indicates less friction.

[BOOT]

A bit of info bout stamped rockers https://youtu.be/AjI1i8Mk01Q

[jeff swisher]

I was thinking how would I test that rocker heat with this engine not in the vehicle yet.
AAAHHH I can use my other engine in my running 57 chevy and swap some of these new rockers on and do a test drive.
Then check heat and yea I have a temp gun.
Good idea.

I am more concerned with the rocker not filling up with oil and spilling over onto the valve springs and cooling them enough.
I can check spring temps and see if the rocker looks well coated.

Lots of oil at speed under those valve covers.

I do keep spring pressures low as I have done some testing on that with these old school cams 268H 280H comp grinds.
I have found the Beehive which is what i run now can go pretty low on open and seat pressure and run like a scalded dog.
I have this one set up at 100 seat and 260 open on intakes and 240 open pressure on exhaust give or take 3 psi.
Still allows the 280H to rev past 7200 easily.
I seen 7800 with a dumb friend driving, he got back handed and let off the gas finally.
I love the Ovate Beehive.

Stock mild lap like 2 seconds just to see where contact was and it was about .050" on both sides of the slot where the stud goes through.
Completely unacceptable in my mind.
This is the first time I have ever bought NEW stamped rockers.

I am kind of meticulous in my thinking and I think that just will not work well.

I will do the test drive tomorrow unless I get rained out.

[Tom68]

I will see if I can load a picture of a stock rocker lapped and on the left a new rocker that I lapped with what I had.
The contact area on the old rocker is all the way around and I took a black Sharpie and colored the new rocker and then lapped
it and you can see the minimal contact area.
This was after a minute with coarse and fine lapping compound..the contact was less than 1/2 of what you see now.

031.JPG

The triangle marked ones are standard, the better factory ones had a 0 designation there, they'd be a better starting point than something with balls that don't fit.

[BOOT]

I know swapping out some new low mile 1.6 stamped to full roller rockers dropped my oil temp bout 20ish deg.

Also I read somewhere how the stock valvecover height was designed to deflect oil for stamped rockers https://www.moroso.com/valvetrain-oil-deflector67700/

[BOOT]

Also in a thread here some years ago, I was told to deburr that oil hole by the pushrod cup. Was told then it was often where they broke. Gotta deburr a split set that I bought this winter for a budget project.

[Tom68]

I know swapping out some new low mile 1.6 stamped to full roller rockers dropped my oil temp bout 20ish deg.

Also I read somewhere how the stock valvecover height was designed to deflect oil for stamped rockers https://www.moroso.com/valvetrain-oil-deflector67700/

Z28 covers had drippers.

70coverwide.jpg

[BOOT]

So did the C4 Vettes But it was splash from the height that I read.

[F-BIRD'88]

IMHO the OEM valve cover dippers are very important.
Apparantly the Crane "Kool-Nuts" serve a simular purpose to get max oil on the rockers.
Running the new and the lapped rockers on another engine is a great idea. Especially if it has mild/ moderate springs. (street stuff). 1.6 rockers will require that guide slot in the head be made a bit londer toward the rocker stud.

[BillK]

Jeff,
Do you mind telling us what brand rockers they are ? When I was doing some dirt track engines years ago and they had to run factory style rockers we always had the best luck with the Crane "Nitro Carb" rockers. They had grooved balls. I would be afraid of the ungrooved balls getting oil starved with any higher than stock spring pressures ?

I have a set of Comp big block ones on the shelf. I might try some Prussian blue and see how they look. Not sure if i would want to lap them or not.

[BOOT]

Also stud girdles, some more than others. I noticed with my valve cover off that some oil was bout to drip off the curved part of the Jomar's right onto the retainer because of the design.

You can see what I mean in this pic I googled(happened to be a Chad S FB post LOL) https://www.facebook.com/speierracinghe ... 876390535/

1932776_902927833057206_3457915854136751412_o.jpg

[F-BIRD'88]

The Stamped style rockers I use on my Vortec 406 are the Crane branded with the roller tip. I had these on my old 350 also.
No idea who manufactured these for Crane.
I'd like to get additional sets of at least equal quality.
No idea if the roller tip on these add any value.
Doesn't seem to slow it down any.

[Tom68]

The Stamped style rockers I use on my Vortec 406 are the Crane branded with the roller tip. I had these on my old 350 also.
No idea who manufactured these for Crane.
I'd like to get additional sets of at least equal quality.
No idea if the roller tip on these add any value.
Doesn't seem to slow it down any.

My reservation with those is they are the opposite to what Chev developed for the LS.