Inliners International Forums General Discussion Hi Performance Stovebolt roller rocker arms

I doubt he'll get any orders at that price.

And who is running a stovebolt at high RPM with high enough spring pressures to demand a roller rocker in the first place?

Notice nothing about ratio, which is the only thing that would interest me.

I think there may be a market, but:
The exhausts aren't needed if the exhaust duration is higher.
That removes 1/2 the details, only need left & right.
The really small intake valve stem angle (it's not vertical) is can probably be ignored safely, making the rocker a see-saw with the adjuster ball center, the shaft center, and the roller axle directly in line.
The actual intake width (nominally 15/16" = .9375") is slightly over 1" with the valve-side lever overhanging the body a tiny bit. The basic design can be split length-wise, and L & R made by simply reversing the sides to "point" the lever at the valve.
A ratio increase is what most people want. The B&B was advertised at 1.7:1, which probably means the adjuster was moved toward the shaft by about 5/32" to 3/16". This is probably safe, although the pushrod clearance hole must be elongated.
I suggest a bushing rather than needles for the shaft.
The price could be reduced a bit by using a radiused pallet instead of a roller tip. The very long lever makes the thrust angle smaller than common V8 rockers. If the body is aluminum, the pad must be attached (duh) but if it were steel plate it only needs local hardening.

Bear with me here...Is it possible to weld up the adjuster hole and then redrill it closer to the pivot point and still have a rocker of adequate strength? Yes,it's cast iron........

Yes, but I'd certainly use a smaller thread (which means new pushrods) to keep as much metal as possible. Just going from the stock 7/16-20 to the common & safe 5/16-24 saves 1/16" of re-location. The NOS late intake rocker I'm using for dims has about 7/32" (.219") from the close edge of the 7/16" thread to the end of the wide flattened pad where the adjuster nut sits. If the new thread used all of this distance, the remaining surface is not much smaller than the original. What's nice is that even though there's a bit less metal, the stiffness is increased because the distance between the 2 points of leverage (rocker shaft center and adjuster ball) is smaller.
I don't think this can be done (it's too far) because the pushrod is going to hit, and how much you can open them up is going to differ with the block, year, head etc. (not to mention you lose back 1/32" by going to 5/16" pushrods).

On the exhaust again: extra lift doesn't do much - the opening point is under 50-70 psi, and the first .020" blows it down quite a bit. How early, and how long are more important than how far (assuming you have some reasonable figure - like you get with a regrind, like .400").

The exhaust is also why you can't make new stands and change both lever lengths (move the shaft closer to the pushrod hole to prevent PR clearance problems). All 12 shaft holes and all 12 stem ends must line up.

The advantage to moving the adjuster hole is that you don't need to re-think the geometry, and you keep the shaft ID, pad radius, oiling groove and spit hole (all extra work and $$ if you fabricate it from plate).

Anyone have reports of breaking through the casting, hitting water etc. when enlarging the pushrod holes?
I make the holes about 9/16" now?
McGurk suggested 3/4" is enough both for big pushrods and more lift (but not for moving the adjuster over), but that was a long time ago and perhaps castings with more metal in them?

I think the main advantage is the work can be done in a home garage with a TIG welder and drill press.

"The B&B was advertised at 1.7:1, which probably means the adjuster was moved toward the shaft by about 5/32" to 3/16". This is probably safe, although the pushrod clearance hole must be elongated."

My measurements on Barkers indicate that push rod moves a bit more then 5/32:

the difference from stock is pushing .16

I have set of them for my 216 build:



I also have a set of '39 lifters and push rods which I intend to use with them. The early style push rod was alot longer so the angle 'off center' will be smaller.

Since you intend to build custom rockers - why not go for a smaller diameter shaft? This would allow you to move the fulcrum closer to the push rods (keeping them straight) and thus increasing the ratio. It is more engineering - $ - and you would have to build exhaust rockers as well. With off center bushings you could use the stock perches . . .

I was not really looking for orders, I wanted some input, I found very little info on rockers and wanted to get a bit of education,I made calls and got pricing and thought the pricing was high and I was right,CNC Dude,I sent a PM on the HAMB and would really like to see a set built,Let me know what I can do at this end to make it happen.

I can't make out the dials - what are the readings?

I checked the original photos - which are higher res then the ones online:

~2.12 & ~1.207 roughly 1.75:1

Stock is ~2.1 & ~1.4 roughly 1.5:1

So the difference is perhaps greater then 3/16 . . .

Here's a comparison photo:

On Ebay as we speak is a set of 6 Barker hi lift rocker arms. The parts and box looks identical to the one shown above.
They are advertised as fitting 216 and 235 up to 1952.Tom Langdon told me the 216 rockers are different than 235,exact words.I assume this to mean they won't work on a 235-261?

BTW: there are a few of those really special Corvette rockers on eBay as well - only $300.00 for 4!

Problem: they're actually 303" Oldsmobile V8 rockers...

Vizard discusses offset rocker bushings in the "Mini" book, but for the length between stands (4"?), with the 1st and last rockers only supported on one side, I'd rather see a bigger stand and bigger shaft. If the shaft wall now is (just to make the math easy, there are several thicknesses) 3/16", going up to a standard auto size of 7/8" at the same wall is a 44% increase in bending resistance.
Reducing the size to accommodate a bushing with enough wall thickness to allow useful eccentricity doesn't look easy. If .020" is the minimum on the thin side, even dropping to .500" shaft only moves the fulcrum .121".

Those are not exactly the dimensions on the later NOS rockers I have here (mine are slightly smaller), and there is a remark in the old service manual that "the valve positions are different between 216 and 235".
If so, I would expect a small diff in rocker dims.

Very interesting and thanks to all for sharing. I’ll get there someday myself and think 4340/4140 steel will be the way I go. Were the high lift ones made specifically for 235/261 applications as well?

I'd like some opinions on what features potential buyers would require for a rocker arm?

Which rocker:
Intake only, does the most, easier to make (only 2 mirror image shapes), 1/2 the manufacture cost?, or
Intake and exhaust?

Material:
Aluminum (6061 etc.) to save weight, slightly more expensive than steel plate, really should use a HeliCoil® for the adjuster, requires an insert for a pallet tip?, or
Steel (IMHO mild is OK), cheaper, can be slightly smaller, considerably stiffer at the same size, adjuster threads directly to arm, pallet should be hardened?

Higher ratio:
Highest ratio (intake only) that fits all the stock parts (except pushrods)?, or
Highest ratio (intake & exhaust) with new stands and shafts (much more $$$)?

What ratio:
1.6 is almost useless (only adds 8%, .400" becomes .433", .500" becomes .542" etc.)
1.7 looks like a practical goal - +15%, .400" becomes .460", .500" becomes .575", etc. but the pushrod will definitely need more clearance in the head and block
1.8 may be too close for the pushrod?
2.0 isn't possible without re-making every single part, plus head machining

Shaft bearing:
Bronze bushing, cheaper, can use the old shaft, lasts longer?, or
Needle bearings, shaft must be new, excellent or chromed for size and hardness, more $$, dirt sensitive, shorter life expectancy?

Tip:
Pallet (radiused pad) as original?, or
Roller tip, more alignment sensitive, better guide life?

2024-T6 or 7075-T6 is what current aluminum rockers are made of, or should I say, better quality aluminum rockers are made of(Jesel, T&D, etc...)6061 is really one of the the lowest strength grade alloys and not good for a product like this that has the potential to have the load bearing it could be subjected too. I think 1.7 ratio would be a good one to select, and a bushed rocker with a roller tip would yield a pretty good all around product.

Some sort of steel alloy could be a second choice, but the cheaper material costs compared to the aluminum would be made up for or exceed the aluminum in the longer machining time to make.

I am just curious and look forward to the answers from the experts but at 1.7 ratio, how close to coil bind would stock height valve springs get?

With what cam?

On the 261 I'm building right now the stock springs come within .060 of binding with the correct installed height at .430 lift.This is too close and spring life will be shortened.
As I mentioned elsewhere I'm using stock Buick 455 springs with a aftermarket retainer.This set up installed out of the box at 1.9 inches with 210 pounds at .430 lift.Good to about .480 lift.This will vary depending on where the valve seats are located.

Manufacturing process would be influenced by what one has to work with. My reasons for going with alloy steel and a radius pad would be to make use of my recent CNC laser heat treating and welding capabilities. Hardening the pads to 55-60 HRC takes less than a second.


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Holy moly, didn't know anyone had anything this cool in E-town. I agree, steel is way better than Aluminum if you can treat it right.

Do you have a laser in your own shop or did you get someone to do it for you?