Forum

[Jakub]

Soon I will be installing new pistons after cylinder rebore, is there recommendation about rings position? Some manufacturers recommend to install gap in front and back or with three ring set them 120 degree apart.

Also, I read that recommended torque for the head nuts is 22 ft/lbs or 30 Nm. It seems fairly light. On the other hand RE suds are pretty thin so maybe it’s right.

I am new here so forgive me asking but is it prevailing opinion, similar to current fashion from other classics dedicated forums, that 20W50 mineral oil should be used? With some usual fringe groups advocating for synthetic on one side and edible oils for the other? With exclusive minority going for super-ultra-hyper-top of the range-space technology stuff with some totally ridiculous price?

[papasmurf]

Also, I read that recommended torque for the head nuts is 22 ft/lbs or 30 Nm. It seems fairly light. On the other hand RE suds are pretty thin so maybe it’s right.

Torque setting depend on how fine a thread is. For instance crank a nut up to 36 ft lbs in a 26 TPI thread and that is over 3.5 tons force on the thread.

[Wheaters]

Possibly not critical but I've always fitted piston rings with the gap in the top one opposite the thrust side; i.e. to the back of the cylinder.

[LanesExplorer]

Ah the vexed question about which oil... For many years now I've used a semi synthetic 15w/40 in my air-cooled vw (yes I know it's not the same as a constellation) and 200000 miles on it seems to like it.
Certainly wouldn't consider veggie oils as they get terrible sticky. And a full synthetic is perhaps unnecessary?

[ed barnes]

If you use a semi synthetic oil in a classic twin the rings wont bed in and it will smoke. Learned that the hard way. 20/50 mineral oil os the only oil the old girls like

[Steve]

Have others had a similar issue with synthetic oil? This may be the answer I have been looking for after a severe smoking issue with a 55 Super Meteor/ Trailblazer rebuild. Steve

[Wheaters]

In the past I've "run in" using a cheap mineral or supermarket oil after a major rebuild then used whatever long term oil after the first or second oil and filter change.

Having said that, I fitted a new high compression piston and rings to my 350 after "glaze busting" the cylinder about a thousand miles ago and just used the normal 20W/50 I always use . The engine smoked slightly for a while but has now bedded in very nicely and that seems to have stopped.