Aftermarket pushrods?

Anyone have experience, good or bad, and recommendations?

Looking at these currently but know nothing they don't tell me: https://www.fagengine.com/products/norton-commando-chromoly-steel-pushrod-set-750-850

Except that they do seem to be heavier (steel v aluminum), which isn't a plus.

I have a couple of bikes with them, very high quality products Dan sells. Kibblewhite Precision Machining is as good as it gets.

Steve Maney offers something virtually identical.

AFAIK the logic goes something like this:

Stock alloy pushrods can bend and flex. That flexing adds to valve train instability (valve float etc).

Steel ones, for all intents and purposes, do not flex in a Norton application. Therefore valve train stability is improved.

So, although they are heavier, and we all know that weight in the valve train is a bad thing, the down side of that increased weight is more than offset by the reduction in flex.

However, I’d argue it depends on the application. Stock rods ain’t gonna flex in a stock engine that isn’t revved hard. The benefits come in engines with bigger cams, heavier big valves, stronger springs and high revs.

After market alloy rods like those made by LCR Ken (if he still does them) and JS are also very good.

2 points of interest -

1. All aluminium, steel & titanium pushrods having equal weight have the same compressive stiffness.

2. The buckling load is determined by the 2’nd moment of area of the pushrod cross section and is independent of the material strength.

What is critical for a good pushrod is straightness and a symmetrical cross section throughout its length to ensure the load path is a straight line through the center.
A bent pushrod or an end fitting that is not coaxial with the rod should be binned.

Addendum to the above buckling comment.
Theory assumes a long column and a frictionless pivot at each end so probably not strictly true for a pushrod.

I've got no science to share. I've got solid end to end chromoly pushrods in my SBC. I would use something similar in a Norton engine. I'm not sure about the added tips at either end of the chromoly pushrods for the Norton. However, I would imagine Maney knows what works if he is selling nearly identical pushrods.

The worrying about valve train weight is mostly nothing to think about in a street bike or even a race Norton unless it is a drag or land speed build. My engine is just as quick, actually quicker, with the stock valve train as it was with the popular higher priced stuff. Maybe that's a little unfair though. I've dialed some other things in since going back to the stock valve train lifter and pushrod parts. Anyway, if I were to do another version of my 750 engine, I'd install those pushrods.

Thanks all. I was/am more concerned about the OEM aluminum pushrods fatiguing than anything else. Bike is currently undergoing at least its second rebuild, given I'm overboring to .040 (came to me with .020 oversize pistons already but the DPO or his mechanic screwed up the bore job). My point is I have no idea how many miles on the original components.

Still, I guess I'm inclined to reinstall the stockers.

Thanks all for your inputs. - BrianK

I rebuilt my 74' Commando this past winter. It is my first Norton build. I did install new Kibblewhite chrome moly push rods. I also installed new Hepolite H-beam con rods. I never expect to recoup money spent on these builds and since I don't spend much time or money on another "expensive" hobby, and I do all except the machine work myself, I don't mind adding a few hundred dollars to the total cost of a build. Aluminum does fatigue with time and use, and for less than $600.00 USD, I eliminated those possible failures. I bought this bike from the original owner and this engine had 32,000 miles on it.