We are currently running on the new domain and server: www.Speed-Talk.com

IMPORTANT: Update your bookmarks to https://www.speed-talk.com/forum/
(Right-click the URL and select "Bookmark this link")

What's with these goofy SBC rocker arms?

General engine tech -- Drag Racing to Circle Track

Moderator: Team

turbo camino
Member
Member
Posts: 145
Joined: Sun Aug 10, 2008 11:51 am
Location:

What's with these goofy SBC rocker arms?

Post by turbo camino » Fri Nov 08, 2019 9:35 pm

Image

(Very first thing: NO, I do not own these. NO, I am not considering buying. Just curious WTF is going on. Even if the concept is workable the rockers themselves definitely aren't; in the stock photos it shows an integral pushrod seat in a "stainless" body, not inserts - that ain't gonna last long enough to make it around the block twice.)

How are you supposed to use these things? Are there parts not shown in the photos, like pedestals? Cause I can't see how they would work without them. If they just float between valve tip/pushrod/adjuster like a single stud-mount rocker, you'd never be able to get or keep the shaft horizontal and roller to tip contact would get all jacked up.

What's missing here? Is it even possible to put these on an engine and have it run afterwards?
DON'T PANIC

Walter R. Malik
Guru
Guru
Posts: 4536
Joined: Tue Jul 24, 2012 11:15 am
Location: Roseville, Michigan (just north of Detroit)
Contact:

Re: What's with these goofy SBC rocker arms?

Post by Walter R. Malik » Fri Nov 08, 2019 11:31 pm

turbo camino wrote:
Fri Nov 08, 2019 9:35 pm
Image

(Very first thing: NO, I do not own these. NO, I am not considering buying. Just curious WTF is going on. Even if the concept is workable the rockers themselves definitely aren't; in the stock photos it shows an integral pushrod seat in a "stainless" body, not inserts - that ain't gonna last long enough to make it around the block twice.)

How are you supposed to use these things? Are there parts not shown in the photos, like pedestals? Cause I can't see how they would work without them. If they just float between valve tip/pushrod/adjuster like a single stud-mount rocker, you'd never be able to get or keep the shaft horizontal and roller to tip contact would get all jacked up.

What's missing here? Is it even possible to put these on an engine and have it run afterwards?
One could use them just like regular stud type rocker arms but, no guide-plates are necessary.

The adjustments would need to be very close to the same; intake & exhaust, to keep the fulcrums near level.
http://www.rmcompetition.com
Specialty engine building at its finest.

User avatar
MadBill
HotPass
HotPass
Posts: 14380
Joined: Tue Nov 15, 2005 10:41 am
Location: The Great White North

Re: What's with these goofy SBC rocker arms?

Post by MadBill » Fri Nov 08, 2019 11:46 pm

Side movement is constrained by the spacer sleeves between each rocker pair.
Billions of insert-free steel rockers are in service.
They would be fine with hydraulic lifters.
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

midnightbluS10
Expert
Expert
Posts: 752
Joined: Sun Oct 20, 2013 8:41 am
Location: Shreveport, LA

Re: What's with these goofy SBC rocker arms?

Post by midnightbluS10 » Sat Nov 09, 2019 12:13 am

Who makes those, anyway?
JC -

SUPPORT THE RPM ACT :!:

https://www.sema.org/rpm-bill-summary

turbo camino
Member
Member
Posts: 145
Joined: Sun Aug 10, 2008 11:51 am
Location:

Re: What's with these goofy SBC rocker arms?

Post by turbo camino » Sat Nov 09, 2019 12:17 am

So how do you adjust the valves? Moving one adjuster even 1/8 turn tilts the shaft and cocks the rollers on the valve tips, fairly sure it'd be impossible to get the adjustment and roller-to-tip angle both right at the same time. With most cams having asymmetrical lobes you can't just use 'zero lash plus X' as a reference point. What am I missing?

I see the advantage of using a common shaft, the design would be neat if it used solid pedestals underneath, but floating like that (vertically via the adjusting nuts, not side to side) looks like an absolute nightmare to work on.

midnightbluS10: "Brand" is Procomp/Speedmaster/whatever garbage. I really don't even want to link to them. They're awful.
DON'T PANIC

User avatar
MadBill
HotPass
HotPass
Posts: 14380
Joined: Tue Nov 15, 2005 10:41 am
Location: The Great White North

Re: What's with these goofy SBC rocker arms?

Post by MadBill » Sat Nov 09, 2019 12:49 am

It would help if we knew the application, but I assume the rocker pairs bolt down solidly to half-moon shaped saddles in the heads and are non-adjustable. O.E.M.s usually rely on adequate manufacturing tolerances to achieve the correct lifter preload, but for aftermarket systems, preload is usually achieved by pushrod length selection, e.g.:
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

midnightbluS10
Expert
Expert
Posts: 752
Joined: Sun Oct 20, 2013 8:41 am
Location: Shreveport, LA

Re: What's with these goofy SBC rocker arms?

Post by midnightbluS10 » Sat Nov 09, 2019 12:54 am

Could they be a stock-style upgrade for net lash-style rockers like what you find on LS heads, etc? In that case, you wouldn't need to worry about adjusting valves or having a cam that's too far from stock that would screw with the rockers, would you? I know on the V6 Vortec, anything other than a stock cam usually gets adjustable valvetrain to replace the net lash system.

It seems to make sense to me. It would explain the lack of adjusters on the pushrod side and then you wouldn't have to worry about the rockers being cockeyed because you just bolt them down and tighten to specified torque.

Edit: MadBill beat me to it. I should've refreshed the page before I started typing lol. That's why I was asking who made them to see if I could find anything else about them, like application or any other parts and pieces that may be included.
JC -

SUPPORT THE RPM ACT :!:

https://www.sema.org/rpm-bill-summary

turbo camino
Member
Member
Posts: 145
Joined: Sun Aug 10, 2008 11:51 am
Location:

Re: What's with these goofy SBC rocker arms?

Post by turbo camino » Sat Nov 09, 2019 1:17 am

Application is standard spacing conventional small block Chevy. They are listed as being for 3/8" studs. Stock photos don't show any other parts included. No stands or pedestals or anything else. Apparently, you just drop them over a pair of rocker studs, adjust them, and go. I also don't see how it's feasible without something solid to bolt them down to, you're not alone.

You guys asked for it, I tried not to do it: https://www.ebay.com/183979480636

I'm not a pro, but I've used several sets of quality stainless stud-mount rockers and they all had inserted pushrod seats. If Comp and Crower have to do it that way I really doubt the Procomp copy artists have discovered the secret of making it work without hardened inserts. Of course, there's nothing but stock photos for any of the offshore junk, the actual as-delivered product could have inserts. Some of their stock photos look suspiciously like CAD renderings and not even photos of a real-world object so who knows what you might find when you open the box.
DON'T PANIC

turbo camino
Member
Member
Posts: 145
Joined: Sun Aug 10, 2008 11:51 am
Location:

Re: What's with these goofy SBC rocker arms?

Post by turbo camino » Sat Nov 09, 2019 1:28 am

The rocker material is likely crap, the shaft material is likely crap, the needles are likely crap, the retaining rings are likely crap, the tolerances are likely crap, and heat treat on any and all parts is likely crap. And since they don't need to understand how something works to copy it, the actual usefulness (are there missing parts? they got the application wrong?) is likely crap too. But other than that, they are probably fine! xD
DON'T PANIC

exhaustgases
Guru
Guru
Posts: 6468
Joined: Sun Oct 06, 2013 9:03 pm
Location:

Re: What's with these goofy SBC rocker arms?

Post by exhaustgases » Sat Nov 09, 2019 3:06 am

Maybe a case of someone finding out that things work different in real life than they do in a CAD program?

Geoff2
Guru
Guru
Posts: 1167
Joined: Mon Nov 09, 2015 4:36 pm
Location: Australia

Re: What's with these goofy SBC rocker arms?

Post by Geoff2 » Sat Nov 09, 2019 3:21 am

Maybe they use adjustable pushrods to allow for adjustment?

Keith Morganstein
HotPass
HotPass
Posts: 5555
Joined: Sun Feb 19, 2006 10:19 am
Location: MA

Re: What's with these goofy SBC rocker arms?

Post by Keith Morganstein » Sat Nov 09, 2019 10:03 am

Just slid over 3/8” studs, I’d expect a noisy sloppy mess.

If you set the valve tip heights and pushrod length, then put solid spacers under them, it might work well. (The idea, not speedmaster brand)
Automotive Machining, cylinder head rebuilding, engine building. Can't seem to quit #-o

SchmidtMotorWorks
Vendor
Posts: 10127
Joined: Mon Apr 11, 2005 2:30 am
Location:
Contact:

Re: What's with these goofy SBC rocker arms?

Post by SchmidtMotorWorks » Sat Nov 09, 2019 12:41 pm

exhaustgases wrote:
Sat Nov 09, 2019 3:06 am
Maybe a case of someone finding out that things work different in real life than they do in a CAD program?
You have that backwards, a CAD model would show the problems precisely.
http://www.schmidtmotorworks.com Prototypes, Tooling, Molds.

User avatar
MadBill
HotPass
HotPass
Posts: 14380
Joined: Tue Nov 15, 2005 10:41 am
Location: The Great White North

Re: What's with these goofy SBC rocker arms?

Post by MadBill » Sat Nov 09, 2019 1:21 pm

Keith Morganstein wrote:
Sat Nov 09, 2019 10:03 am
Just slid over 3/8” studs, I’d expect a noisy sloppy mess.

If you set the valve tip heights and pushrod length, then put solid spacers under them, it might work well. (The idea, not speedmaster brand)
We were considering that approach for the new 380" SBF road race engine we're accumulating parts for: steel Comp stud-type rockers mounted on Yella Terra pedestals, shimmed for lash, but now YT has come out with a 1.7:1 ratio pedestal mount SBF set with typical pushrod seat adjusters.
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

Kevin Johnson
HotPass
HotPass
Posts: 8205
Joined: Tue Nov 22, 2005 5:41 am
Location:

Re: What's with these goofy SBC rocker arms?

Post by Kevin Johnson » Sat Nov 09, 2019 1:57 pm

turbo camino wrote:
Sat Nov 09, 2019 1:17 am
Application is standard spacing conventional small block Chevy. They are listed as being for 3/8" studs. Stock photos don't show any other parts included. No stands or pedestals or anything else. Apparently, you just drop them over a pair of rocker studs, adjust them, and go. I also don't see how it's feasible without something solid to bolt them down to, you're not alone.

You guys asked for it, I tried not to do it: https://www.ebay.com/183979480636

I'm not a pro, but I've used several sets of quality stainless stud-mount rockers and they all had inserted pushrod seats. If Comp and Crower have to do it that way I really doubt the Procomp copy artists have discovered the secret of making it work without hardened inserts. Of course, there's nothing but stock photos for any of the offshore junk, the actual as-delivered product could have inserts. Some of their stock photos look suspiciously like CAD renderings and not even photos of a real-world object so who knows what you might find when you open the box.
https://www.ebay.com/itm/Chevy-SBC-350- ... 3979480636

Post Reply