Small block ductile iron rocker arms

[toolmanmike]

Let's talk about small block adjustable arms. Somewhere around here is a photo of small block rockers comparing the stock ones to aftermarket like Crane and Isky but I can't find the post. .
The "loosing adjustment" thread, a sale thread for them, and a discussion with a member about them got me thinking.
I have never known 273 rockers to have lock nuts. I have seen pics of rockers with the lock nuts that were described as from a 340. Of course the TA rockers had lock nuts and one of them was offset for more intake porting. .
Anyone have photos of small block rockers with lock nuts that you know are factory.
How about photos of rockers known to be Isky or Crane. (I think their names were cast in the rocker bodies)

 

[qkcuda]

Mike, I never saw factory adjustable rockers with lock nuts. Back in the day I would remove the stock adjusters, spot face the tops, and install aftermarket adjusters with lock nuts.

 

[Locomotion]

273 rockers were not originally intended for the higher lifts, spring pressures and rpm's that many people subject them to. At some point, they will start to give out and not hold their settings. My memory is fuzzy but I believe I saw something about a special thread was used on OEM 273 rockers - the difference between the adjuster and rocker body causing an "interference" fit which helped hold the adjustment. I'm guessing that the 273 adjusters would have had the "modified" thread. Does that ring a bell with anyone? I went through the same learning curve trying to add Crane adjusters with a lock-nut but the rockers needed the spot-face to avoid breakage. Eventually everything wears out, just like OEM LA stamped rockers, they will take a lot of abuse, up to a point, but can eventually cause the pushrod to punch through the rocker body.

 

[Locomotion]

Of course the TA rockers had lock nuts and one of them was offset to allow for bigger valves.

Offset to allow more intake porting without the intake pushrod hole being a limiting factor.

 

[toolmanmike]

Mike, I never saw factory adjustable rockers with lock nuts. Back in the day I would remove the stock adjusters, spot face the tops, and install aftermarket adjusters with lock nuts.

Me neither.

 

[Johnny Dart]

Mike, I never saw factory adjustable rockers with lock nuts. Back in the day I would remove the stock adjusters, spot face the tops, and install aftermarket adjusters with lock nuts.

So stock adjusters could be removed, and aftermarket adjusters/lock nuts could be installed. Interesting.

 

[Locomotion]

So stock adjusters could be removed, and aftermarket adjusters/lock nuts could be installed. Interesting.

Only if the rockers are accurately spot-faced for the lock-nut. Otherwise any uneven load will eventually lead to the adjuster breaking.

 

[Johnny Dart]

....

 

[RustyRatRod]

Erson also made some as well. They were all copies of the factory iron rockers. The aftermarket rockers used a screwdriver slot adjuster with a nut, if I remember correctly.

 

[RustyRatRod]

So stock adjusters could be removed, and aftermarket adjusters/lock nuts could be installed. Interesting.

Yes, but you must run a tap through the rocker adjuster holes to cut the self locking feature out of the rocker arms.

 

[Johnny Dart]

If you only knew why this thread was started, I'll just leave it at that.

But Mike knows, and once again. CHECKMATE !!!!!!

 

[Oldmanmopar]

Fifth picture the closest one is a original lock nut style from Crane The second one and the rest are rockers I cut to fit. The adjusters are 5/16 and I got them from old Max wedge rockers. All other Big Block adjusters are 3/8

 

[voodoo340]

Not the best resolution, but here is a clip from the Isky catalog, FWIW:

 

[JDMopar]

Rocker Arm Specialties in CA can fix them in pretty short order if needed. They just fixed some 354 Hemi rockers for a friend of mine.