Another disturbing noise from Ruby

[Ivor Hawkins]

As a specialist unit, I’m sure they know what they are doing and setting them square in the bores with say a 5 thou gap (I can’t remember the optimum gap off hand) should be fine.

However, when I was a spotty teenager and thought I knew it all, I rebuilt an old Humber motor and didn’t gap the rings at all, but still got the pistons in and the result was a similar noise to what you have.

I hope I’m wrong!

[Stuart Giles]

As a specialist unit, I’m sure they know what they are doing and setting them square in the bores with say a 5 thou gap (I can’t remember the optimum gap off hand) should be fine.

However, when I was a spotty teenager and thought I knew it all, I rebuilt an old Humber motor and didn’t gap the rings at all, but still got the pistons in and the result was a similar noise to what you have.

I hope I’m wrong!

My worry with no ring gap would be that they'd break when the motor gets hot, with the Humber motor it's good that you got a warning noise. 5 thou ring gap would probably be OK; but I've always used this chart, -which used to be packed along with replacement Hepolite piston ring sets- for gapping piston rings on any motor I've built.



So, .007" for an A7 motor

[Nick Turley]

Hello Denis

Am I going crazy or is your engine going the wrong way round ?

I suspect that the noise could be from your starter motor which will not disengage.
Viewed on your video it should be all turning anti clockwise - your starter is turning it clockwise !

I suspect your problem will be a simple one of polarity at you starter motor.

Hope this helps.

[Ivor Hawkins]

By George, I think Nick could be right!

[Martin Baker]

I had one thought. Could it possibly be the rear crank bearing oil thrower rubbing on the retainer casting? Perhaps even the flywheel rubbing on the bearing retainer if the flywheel has been lapped too much? Maybe try putting the good old LIDL endoscope down the gap to have a look?

[Denis Sweeney]

Well Nick I have to say it certainly looks as tho' it's going the wrong way, totally blind to the obvious.
What have I done wrong to achieve this??
Having put the block back on I honestly thought I had religiously put everything back just as it was taken off, so am pretty embarrassed, but have no idea how this could have happened.
I have today just taken the engine and gearbox back out and they are on the bench and just removed the gearbox.
On visual examination, without any dismantling of the flywheel and clutch, I cannot detect any scraping noise or see any evidence of any score marks of anything rubbing in this area.
I will remove the head to see if anything looks untoward inside.
But how would she even start, she even started on first pull!!
Oh dear!

[Ruairidh Dunford]

The engine is running the correct way.

Did you try the test to see if the clutch was not not jammed open?

[Denis Sweeney]

Yes Ruairidh, check my post of the 19th

[Ruairidh Dunford]

Sorry, I missed this.

[Steve kay]

I remember that single cylinder two stroke external ignition engines in boats such as Bolinders, or Sefffels, (or possibly early Kelvins or Gleniffers, Ruairidh?) would reverse the prop by reversing the direction of rotation, but I did not know that this could apply to a four cylinder four stroke!