Comet Help Please!

[miked]

It has a Steel large (current VOCSC issue) and an Ali small idler of unknown vintage.

Mike

 

[b'knighted]

Ally small idlers used to be vitually consumable, especially when used with nylon ATD gears. It is probably worth changing to a steel idler although this may change the whine into a ringing in the ears whilst reducing the jingling of cash in your pockets.

 

[chankly bore]

Current steel large idlers are probably o.k. but some earlier flame-hardened and over-drilled ones were out of true in at least two planes.Ditch your alloy small idler and fit a tufnol magneto pinion.While you are still on good terms with your bank manager get a one piece steel large idler boss.If you can get your local Section members to help,then spend some time shimming your gears,getting the cam followers tracking central and eliminating backlash between the cam pinion,half-time pinion and large idler.As advised previously,do not run the generator pinion too deep in mesh.Then lock it all up,run a heavy bead of weld around the timing cover and ride it for 20 years or until,as a local Comet-thrasher once said ;"It starts making the usual noises louder than usual."Cheers, F5AB/2A/7945 since 1970

 

[redbloke1956]

Current steel large idlers are probably o.k. but some earlier flame-hardened and over-drilled ones were out of true in at least two planes.Ditch your alloy small idler and fit a tufnol magneto pinion.While you are still on good terms with your bank manager get a one piece steel large idler boss.If you can get your local Section members to help,then spend some time shimming your gears,getting the cam followers tracking central and eliminating backlash between the cam pinion,half-time pinion and large idler.As advised previously,do not run the generator pinion too deep in mesh.Then lock it all up,run a heavy bead of weld around the timing cover and ride it for 20 years or until,as a local Comet-thrasher once said ;"It starts making the usual noises louder than usual."Cheers, F5AB/2A/7945 since 1970

Hi Chankly, I am hoping (or was hoping) to do the old timing case shuffle for the first time this weekend and have just read this post, why do you recommend the one piece steel large idler boss, I have some new spindles and both idlers, new cams and pinion but never thought of the large idler boss? Is there something I should know?
Thanks
Kevin

 

[nkt267]

but never thought of the large idler boss?

The shaft can get loose in the aluminium boss to the extent that when you remove the unit the shaft falls out..John

 

[bmetcalf]

Also allows you to use a nylock nut instead of a regular nut and locking plate ET220.

 

[chankly bore]

Yes, the answers you have got are right.I have seen the alloy bosses worn and cracked on some motors,and not holding the shaft on most others-therefore even a good concentric large idler will wander,being only retained by the steady plate and 5/16" BSF nut.This situation can only get worse.The Series "D" steel idler boss was a genuine improvement.If you want to do something else to improve matters make slightly longer retaining studs E87 and fit "aerotight" or nyloc nuts instead of the original punchlocking.Cheers,F5AB/2A/7945