Eye Candy Rocker Arms

I had the head off my 750 AHRMA racer, and the rocker arms are so pretty I thought I'd post some pictures. These were lightened and shot peened by Bob Gorsuch, now retired, at Excello Plating, long since closed. I suspect you get the same funtionality out of just lightening the lumps at the ends, but these are so good looking that I'd probably have more of them done if Bob was still around.







Does anyone know of a shop that still does these at the same level of quality?

Ken

I did the ones on my 850, look similar, just not shot peened. My combat came done by TC in the 70's, I don't have any pics of my 850 but here are a few of the Combat.

The rocker arms in my short stroke Triumph 500 always looked like that, but it revved to 10,500. I haven't bothered to do it with the commando engine, It might give a bit of reliability, the valve springs might last a bit longer, but the engine is designed to only run to 6,500. It comes down to the same old choice - torque or top end.

On mc-engine list they just went though significance of lightening rockers. One fella made a inertial set up to test how much to find only lightening the ends mattered. If ya take some more off the ends of the ones Ken has it allows foul-less push rod slipping full up into head first time every time no sweat. So that's best reason I know to relieve rockers. Cryogenic a good idea too before peening.

Here's Dunstal's risk taking candy art.


Here's some others Ken has on hand right now

Not shot-peened, and not as emaciated as the Dunstall examples, but here are my efforts.
Sorry about the rather blurry image

The lightweight adjusters & dural locknuts came from RGM

Beautiful, but you guys need to get out a bit more.

Damn Andy they look sweet as can be, yum! hobot

Very nicely done indeed !!

Ken -

Bob passed away a few years ago. His magical shop in the heart of Excello . . . . Zyglo, Magnaflux, hard chrome, shot peening . . . . what a great guy, a bygone era. I'd go in there, a kid with not enough money, and he'd help me out, charge me what I could afford. Can you imagine what he'd have to say about our President?

Are those adjusters from RGM radiused where they meet the valve stem?
Where to purchase mushroom ones as well if any one has info on that please
Regards Mike

Brooking 850 said:

Are those adjusters from RGM radiused where they meet the valve stem?

Click to expand...

http://www.rgmmotors.co.uk/search-result.asp

Certainly are, couldn't see that when I checked their website.
Much appreciated Mark
Regards Mike

'shroom sources

http://www.nortonownersclub.org/noc-cha ... /585452580

http://www.ebay.com/itm/NORTON-COMMANDO ... 1021169057

http://www.britishbikeconnection.com - US$ 28 plus shipping

Thanks Steve for the links
Regards Mike

Ok Brooking 850 = Mike. Realistically our short stuby rockers ain't dragging the valve train down all that much, even as dog bone as stock, so By Far the most noticeable benefit is to aggressively relieve the very ends of the push rod side so the push rods are no longer a hang up neck straining swearing task. For some rpm relief get the 6 mm k/W valves with Jim's Schimdt's bee hive springs or other racing springs, lighten the lifters some and fit the lighter adjuster parts and replace the thacker spring spacers with custom fit bronze spacers. Anywho grinding and sort of polishing Peel's lifters was one of her highlights making me feel like a hot rodder machinist. Peel's rockers were also cryogenic tempered just in case and Ken say head good to go even after horrific tach needle disappearing act that ended first edition Peel spunk by taking out cam chain tensioner and oil pump snout which screwed with Boyer timing and cut power to 4900-5000 tops.

Thanks Steve, have my list for Bike #2 KW B/Diamond Vv's and Behive springs are on that list and ordering starts later this week.
have changed track a bit with bike from cafe racer to track bike, so still looking at options on other parts, engine and head path is defined now.
Regards Mike

Sorry I missed the question regarding the tappet adjusters - the Forum Will Provide as they say

I didn't go mad with mine - just one day spent grinding and Dremelling. My main objective was to get weight out of the ends to get the inertia down.

I've put Jim's beehive valve springs in, and am waiting for an opportunity to make up some shims.
Machining the valve stems to accept the additional height required was quite fun (not), but Jim's valves have this done already and are all ready to go - I'll do this next time.



I can hardly wait to get this engine sorted (4S cam, Dunstall barrells & high comp pistons, PR spec head), and see what it does - apart from scare me a little

lcrken said:

Does anyone know of a shop that still does these at the same level of quality?Ken

Click to expand...

Those are nice looking rockers Ken. Sanely lightened, not insanely like the Dunstall rockers. Recently a guy on Ebay was selling rockers which were sanely lightened like yours, but they were not shot-peened. The guy was asking about $200 for them as a "buy it now", but they ended up going for about $165 when the auction was done. Maybe he will put another set on there at some point?

Seems cheap for four rocker someone has also put a good days work into, even if you have to have them shot-peened yourself.

I got a set of the Dunstall insanely-lightened/polished rockers in a large lot of used parts from an old dealer, one was missing from the set and I would guess it had snapped in two for someone.

When you grind the top and bottom of the rockers to a knife-edge for the whole length, you are making it very vulnerable to breaking especially if that edge gets nicked. Since all the inertia is at the ends of the rocker, lightening the ends and keeping the rest of the rocker broad and strong should make the best all-around job.

I recently did something like this to a set of rockers for a 650ss, just for shits and giggles while the head was apart. I figure a few little things like this might give a small amount of insurance if anyone ever misses a shift etc.....

The real danger of grinding on sides is there is an oil passage near the surface, if broken into new rockers are like $80-90 each, so the ebay seller lost out a lot on that sale. If the seeming knife edge was much a risk then Peel's would of been all over the place. The narrow top edges did change my approach to compression release mechanism though.

Anyone have first hand experience with (or know of someone) breaking/bending a rocker?

Pulled the head on the 500 Norton a few weeks back to find the two exhaust valves hit the pistons due to a sheared timing pinion key; valves were bent but pistons fine. Rockers were lightened (not insanely) and no damage. Interesting thing (in a strange way) is that the rocker spindles actually bent. These are the older scrolled type rocker spindles with a necked down center diameter.