Discussion in 'Norton Commando Motorcycles (Classic)' started by Fast Eddie, May 17, 2019.
Could someone please tell me the outside diameter of a stock Commando aluminium pushrod ?
I measured four which varied from 9.51 to 9.58mm.
Thanks a lot LAB, that’s exactly what I needed.
Why do you need the info Eddie? Are you having some special ones made?
The inlet pushrods on the 920 I’m building are rubbing against the inside of the head.
I wanted to ascertain if it is my pushrods that are too fat.
They are not, so I’ve got to get fiddly and remove some material from in there it seems.
But I’ve no idea why !!
Maybe something with the rockers?
Stock 1S cam?
If hot rod cam then you may well have rubbing on the exhaust side.
As the (shorter) rocker goes up it also pulls the pushrod toward the front of the engine.
This is all well known (by some) and is why early barrels and head gaskets were "upgraded" to allow the forward swing.
88 vs 88SS and 99 vs 99ss, the SS engines having the higher lift SS cam.
Dommy SS Barrels
JS3 and Maney barrels IIRC.
It’s a Maney cam and Maney barrels. Rubbing is up in the head though, so nothing to do with barrels or head gasket.
My issue is actually the inlets... not exhausts.
Could be a rocker issue, I have some others so will check.
I sincerely hope it’s not the rockers though, they are brand new AN rockers, lightened and polished by Pete Lovell... probably the most expensive Commando rockers in history...!
Pickies ? [please]
Of what in particular ?
your shiny rockers .
Oh these! I am pleased to confirm that these are NOT at fault (phew)!
Ok, basically, it looks like the head was not machined correctly all those years ago (Friday afternoon job)?
The pushrod tunnels were kinda off centre, to tight for the inlet on one side and the exhaust on t’other.
I got a tools down inside and relieved quite a lot of material. Doesn’t look as nice as if I’d got it set up on the mill like you flash lads, but it’ll work!
oh err [drool],not long now eh ?
Id be as chuffed as a chuffed persons chuffed bits.
I will be when it’s running and hoofing out a gazillion BHP !!
Those rockers look like they'll keep your valves under control up to 13000 rpm I reckon
They are nice!
And the pushrods from Ken (LCR) are lovely n light too.
It ain’t gonna be a rev monster, but it’s nice to know the valve train will be nicely under control.
Assuming I ever get it finished... it’s nearly 3 years since a started collecting the bits for this job...
Triumph pushrods are often made out of high-tensile steel tube instead of solid aluminium and are much thinner than Norton pushrods.