E: Engine More Adventures with the Comet

[manxman]

Before I get to the valves, see below the cam lobe and follower wear. A significant divot in the inner lobe.

The Spares Company does a good job setting the cams in the pinion? Or are there better options (I don’t have the equipment myself). Pinion itself looks to be in good shape, would like to keep it.

 

[Martyn Goodwin]

Both the Cam and the Cam Follower are toast. The wear has gone completely through the case hardening. I suggest you replace the cam and BOTH cam followers. With that much wear I would also be taking a close look at the rocker arms in the head. The forked end that engages the valves should have a nice smooth 0.5" radius on it - if it has a significant flat worn on it the rocker arm(s?) will also need replacing.

The saving grace is that parts are readily available.

You can remove (and refit) pinions with a suitable drift and a sturdy bench vice to act as a mechanical press.

As to pinion positioning I maintain it is not important as the best way to set up valve timing is to ignore any pinion markings and use indicator gauges, setting for equal valve lift at 4 BTDC. You can measure the lift at the cam follower cup, at the top of the pushrods - or much more difficult, at the top of the valves

 

[Bill Thomas]

You also have an alinement problem, The follower should be touching the cam fully,
I see there is a lip on the follower, So it was off to one side ?,
Try and study where the shims go .
Also make sure where ever you get your cams, They have oilite bushes, There is a Chap in USA who puts in bronze bushes = Not good for Vincent's ?.
Good Luck Bill.

 

[vibrac]

Yes the only virtue in fitting the cams in a particular position if you are using the 4 degree timing is that the initial setting of the cams on the spindle is done by lining the 'slots' in the cam pinion between the push rod tubes as shown in the picture in Richardsons. hardly a problem because if they are not there a line with a pen can do the same job or else another few seconds of twirling.
This lockdown apart from building my Comet I have learnt a lot of tricks putting a Douglas post war twin together when it comes to setting up the cam timing on it I cant wait to try the both valves open just before TDC method.

 

[Normski]

The Spares Company does a good job setting the cams in the pinion? Or are there better options (I don’t have the equipment myself). Pinion itself looks to be in good shape, would like to keep it.

With possible postal delays and costs it may be worth checking to see if John Healey’s Coventry Spares will supply a new cam and fit to the pinion for you.

 

[Normski]

You may find the thread ‘Do I need a refresh’ started by kennyNUT helpful.

 

[manxman]

You may find the thread ‘Do I need a refresh’ started by kennyNUT helpful.

Very helpful! Thank you.

 

[LoneStar]

With possible postal delays and costs it may be worth checking to see if John Healey’s Coventry Spares will supply a new cam and fit to the pinion for you.

I sent pinions and spindles to Megacycle Cams, they pressed in new cams with bushes sized to the spindles. I believe Coventry gets their cams from Megacycle.

 

[Bill Thomas]

I think it's Megacycle who fit bronze bushes, Not good for Vincent's, They have been told so
maybe the now fit oilite, Give them a phone call ?.

 

[davidd]

Somehow they were sent a bag of Oilite bushings from McMaster Carr and offered to install them in the Vincent cams. Their cams are quite good and it's nice that they have accommodated Vincent owners by supplying the Oilite bushings. I recommend asking them for Oilite specifically when you order cams from them just as a sign of support for their decision and to make sure you get what you want.

David