Rocker adjuster screws - a plea!

[72degrees]

The ball headed adjusters on the rockers are M6 FINE thread (0.75 pitch I think?). So please don't tighten the lock nuts like a gorilla!

I've just been having a go at lightening some used rockers I got from NLM as an experiment (OK - only managing to lose 3 gs or so but nice and shiny ). I'd sorted through the box to find ones with 'good' thrust pads and decent looking bushes. Some were without screws and the threads have turned out to be OK and so I shall swap in adjusters from the ones off the engine. One complete with adjuster and nut freed up OK. I should have known to leave the one with an adjuster but no nut in the box. The thread is buggered. I suppose it might have just enough range of movement left as an emergency 'spare' (I did have one adjuster strip the thread years ago at a hill climb).

The lock nut only needs nipping up, so leave the half inch drive 10mm socket and tommy bar alone and use a suitable tool!

Talking of which, has anyone tried using Titanium nuts - lightness where it matters (the end), but would they survive?

[norbert]

No experience with titan nuts

This rockers lost 2 gr each (the upper one is original)

k-DSCI0179.JPG (63.21 KiB) Viewed 9161 times

till now about 10 000 km without problems

[72degrees]

That photo was part of my inspiration. Along with the scene in 'On Any Sunday' of Mert Lawill fettling the cam followers on the 'No 1' plate HD, and illustrations in 'Tuning for Speed'. My scales aren't accurate enough to be sure of the weight loss per rocker (d'oh, possibly better to weigh all four v. four standard ones). Some research turned up M6 x 0.75 Titanium nuts from Germany and on the face of it they could save another .25 to 0.5 g per rocker, but rather expensive at nearly £12 , plus postage for 5. I'm also not sure they would take the shock loading in this application.

Anyway, all ready to be re-assembled on the shafts now. The bushes are all OK but the rocker shafts are very slightly worn and no new items available. Oh well, less friction

[Ming]

Sounds as though the easiest way to shave off some weight would be to go on a diet?

[72degrees]

Sounds as though the easiest way to shave off some weight would be to go on a diet?

Sigh! That joke has already been done the first time I mentioned it.

I know it's a waste of time looking for more willingness to pick up the rpm smartly. If I was at all serious about putting in competitive times I wouldn't be riding a Morini would I ?

[devon wrinklie]

I've met Mr Pete, he's built like a racing snake.

[SupermotoDave]

What you need for improved pickup is a set of original mk1 rods with the super lightweight small diameter big end studs, every little helps and you are not looking at prolonged high speed running.
Plus lighter weight oil. The crank gallery is filled with it so going down 10w must be like lightening the crank. And if you reduce the torque you tighten the rocker nuts and con rod caps to then you can save a few pounds.

[72degrees]

What you need for improved pickup is a set of original mk1 rods with the super lightweight small diameter big end studs, every little helps and you are not looking at prolonged high speed running.
Plus lighter weight oil. The crank gallery is filled with it so going down 10w must be like lightening the crank. And if you reduce the torque you tighten the rocker nuts and con rod caps to then you can save a few pounds.

Had me going there until the last sentence The 10w-40 probably doesn't get very 'thick' even after a prolonged warm up in the paddock

I'm also going to no base gaskets just for giggles. Just as well I've got a spare engine to swap to eh?

[72degrees]

Well that's interesting. The rocker adjuster screws supplied by Mdina are a different design. Instead of a square to twiddle they have a socket for an Allen key. Hmm. I wonder. Yes they are a bit lighter, particularly when paired with a titanium nut. The one in the photo is 1mm pitch so won't fit but I can't see a M6 x 0.75 being any heavier. So 1.5g to be saved on each rocker right at one end where it matters . I might invest in those expensive German nuts after all.

Anyway, going very well just now on my usual shakedown run to the Greasy Spoon and back. Now reverted to S&B filters and the main jets back up to 132. As an experiment though I left the X8 needles in. Very promising with really only a slight stumble now at the dreaded 5500 rpm and partial throttle under 'steady state'. Possibly in the slide cutaway region, but at Dellorto prices I can live with it as this engine won't be spending much time at a 'steady state' once based in the hill climber. After it has a few more miles on the new pistons I may even take it to a rolling road dyno with exhaust gas analyser to try to pin it down. There's a place been recommended to me not far away that apparently know a bit about Dellortos because they 'tune' Lambrettas and also won't just want to sell me a (non existent) dynojet kit. I shall call in soon and see what reaction I get and an idea how much a bit of dyno time will cost me. Getting a number for the power output would be incidental and pretty underwhelming I suspect.

rocker screws.jpg (228.27 KiB) Viewed 9005 times

[MickeyMoto]

5.5grams or able to withstand 5.5g?

[72degrees]

5.5grams or able to withstand 5.5g?

Ha! The former but possibly the latter? What acceleration will it be reciprocating at when revving at 9000 I wonder? F=ma or something - ICBA to do the maths

[Al B]

Why not Aluminium nuts? Surely they'd be even lighter

Or just reduce the thickness of the originals

Al

[MickeyMoto]

5.5grams or able to withstand 5.5g?

Ha! The former but possibly the latter? What acceleration will it be reciprocating at when revving at 9000 I wonder? F=ma or something - ICBA to do the maths

If it was reciprocating at ,9,000 rpm there would be no acceleration?
However, the rocker arm will be accelerating every other stroke and surely the cam design would be a factor. A steep ramp meaning more G?

My brain hurts... IACBA to do the sums...