Polished rockers...

Bob Z. · Oct 17, 2017

I opened this 1971 Commando that had been stored for 20 years and was pleased to find the lightened and polished valve rockers and light-weight spring keepers.
Does anyone still do his stuff?

Danno · Oct 17, 2017

I did, 32 years ago when I screwed the SS clone's Mk III engine back together. Also eliminated the springs on the rocker shafts and shimmed each rocker to center. It's a little rattly , but it still runs. I used the hoilow adjusters, but took them out when I got some mushroom-head tappets.

gortnipper · Oct 17, 2017

A la Mssr. Comstock

Fast Eddie · Oct 17, 2017

Mine, on the Blue Bomber / Trident Hunter...

Not in this pic, but I use tappets from RGM which are broached for an Allen key and have Dural lock nuts, probably saving more weight at the extremity than the actually work on the rocker arms.

Amazing how’s horridly ‘club footed’ the stock arms are IMHO.

Danno · Oct 18, 2017

Back when Combats were rounding their cam lobes, lightening the valve train was thought to save wear and tear on the cams. The Dunstall tuning handbook showed how to enlarge the holes in the lifters for more weight reduction.

baz · Oct 18, 2017

Yep I always lighten the valve gear,rockers valve spring retainers and follower's ,I take my 750 above 7000 rpm sometimes and although lightening the valve gear probably makes no difference at all it's not hard to do, and I would hope it gives the cam etc an easier life cheers

SteveA · Oct 18, 2017

Yes, I do mine like the old school ones. And I use broached allen key adjusters, but I gave up on the alloy nuts after checking the tappets at a race meeting when I found a damaged thread in one nut, and had no spare in the box. Heavy Duty thread lock saved the day....well at least until the belt pulley came off!

I now use steel and carry spares! That extra little bit of weight won't have much effect.

I think what the picture of the Jim Comstock solution shows is that the weight reduction is more important the further it is from the pivot point. And that it takes a long time to polish the whole thing, for very small returns. OK for us amateurs, but too much time at professional rates!

lcrken · Oct 18, 2017

I used to get them lightened and shot peened buy a guy here in SoCal at Excello plating, but he's long retired now. This is an example of the ones he did for me. It's clearly overkill in terms of benefit vs. labor time, but they are lovely to look at. Steve Maney used to have a guy who did a nice job of lightening rocker arms, but I don't know if he is still available.

Ken

Bob Z. · Oct 18, 2017

Your photo got me to dig out the old Reg Pridmore catalog for a look at his Norton services circa 1978.

oldmikew · Oct 18, 2017

how about titanium nuts on the tappet adjusters ... i had issues with dural ..

gortnipper · Oct 18, 2017

lcrken said:
I used to get them lightened and shot peened buy a guy here in SoCal at Excello plating, but he's long retired now. This is an example of the ones he did for me. It's clearly overkill in terms of benefit vs. labor time, but they are lovely to look at. Steve Maney used to have a guy who did a nice job of lightening rocker arms, but I don't know if he is still available.

Ken

Oooh...sexy!

Hobot · Oct 18, 2017

New age whimps.
http://i184.photobucket.com/albums/x93/hoboter/rockerstop_zpsf7bc10be.jpg

Hobot · Oct 18, 2017

Only risk is exposing the oil passage cast near surface of the lever blades. Good to go way past end of red zone on 2S cam lifts even w/o BSA cross breeding adaptations.

acotrel · Oct 20, 2017

With a commando engine, by the time you get valve float with standard rockers, the bottom end has exploded.

acadian · Oct 20, 2017

What about friction from the thackery washers themselves? Wouldn't that be more of an issue?

Onder · Oct 21, 2017

All true but perhaps, and only perhaps, lighter rockers might lengthen cam face life.
Agree that high rpm is likely unnecessary.

Polished rockers...

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