E: Engine Camshaft oil feed holes

[Mike Davies]

After having my front cam reground, I'm re-bushing it and wondering if I should drill oil feed holes like the ones on the rear cam. Anyone have any advice and what size and kind of drill bit should I use?

Also, one bush has turned and worn a few thou inside. The new one seems nice and snug. A bit of loctite you think?

 

[Bill Thomas]

Hello Mike, Are you saying the cams are not drilled ?, Or just the bushes ?,
That could be tricky , Very hard probably Stellite weld,
I have just looked at one of the last Gary Robinson Cams and they have holes in them,
Another thing is the bushes , I think Davidd told us Mega cycle were fitting bronze bushes ?,
Which are not good for Vincents ?, Unless you give them a lot more clearance,
Even Oilite Bushes, Which is what they should have ?,
I would make sure yours are not too tight , If you have what you think is a loose fitting !.

With the long cam some of us fit an extra bush, Under where the cams are ?.
Good Luck, Bill.

 

[oexing]

In case your cams are not drilled, have them spark eroded as drilling might be traumatic. The holes should be on the base circle just before lift begins, see photo below.
Bronce bushes should be allright when getting the right stuff. I have CuSn8 2.1030 bushes in most places where bronce is recommended. This type is like phosphor bronce but no phosphor content. Make sure you got min. 1 thou but below 2 thou clearance on spindles.
BUT you have to do a mod for safe oil supply to the holes even when a bush has walked. So not just drill the cam holes through the pressed in bushes as holes get blocked when bushes walk. I´d have a look at grooving the bushes along the axial direction where the holes were drilled , groove dremeled in i.d. of bushes - plus another radial groove turned in in o.d. of bush where the oil holes are meant to go . So oil can exit the spindle supply any time for lubricating the cam follower, not just when oil holes in spindle and camshaft bushes line up in a very short moment. Ot did I miss something from remembrance ??

Vic

 

[Bill Thomas]

Are the oil holes really needed ?,
I see now they say the oil holes in the followers are not used,
I think the old cam wear was because of not being hard enough ?.

 

[oexing]

Hardness in itself will not help much,it is the pairing of materials for low wear. Stellite is not extremely hard I think, but the high chrome content helps to fight wear on cams and followers. Like bronce is not hard but a good combination with hardened steel and a little oil added it will be durable.
I don´t share the religion of oil running down pushrods and reaching the oil hole in followers to lubricate the cams. It is a long way with flying pushrods, rockers and all to fling any oil off before somehow finding the badly placed follower oil hole. So lasered the follower hole shut and take care for good supply through the cam spindles instead.
Even spray bars for cam oil suply don´t work as great as intended, better get oil from within cams and out the holes at start of valve lift.

Vic

 

[Bill Thomas]

The old cams were made of Cheese,
I don't think I would bother with holes in the cam,
Just use a good single grade oil.
Just my thoughts !.
Gary used to say he used Stellite 6 on one and 12 on the other.

 

[Mike Davies]

Hello Mike, Are you saying the cams are not drilled ?, Or just the bushes ?,
That could be tricky , Very hard probably Stellite weld,
I have just looked at one of the last Gary Robinson Cams and they have holes in them,
Another thing is the bushes , I think Davidd told us Mega cycle were fitting bronze bushes ?,
Which are not good for Vincents ?, Unless you give them a lot more clearance,
Even Oilite Bushes, Which is what they should have ?,
I would make sure yours are not too tight , If you have what you think is a loose fitting !.

With the long cam some of us fit an extra bush, Under where the cams are ?.
Good Luck, Bill.

Thanks Bill, Yes they had oilite bushes which I thought were a bit too sloppy, with three installed at that. I can't remembernow where the cams originally came from but most likely were exchanged or stellited by Conways back around 1990.
I tried getting cams from Gary Robinson but he had literally just been talked into retiring as he considered making some for me. Good for him!

 

[Mike Davies]

Hardness in itself will not help much,it is the pairing of materials for low wear. Stellite is not extremely hard I think, but the high chrome content helps to fight wear on cams and followers. Like bronce is not hard but a good combination with hardened steel and a little oil added it will be durable.
I don´t share the religion of oil running down pushrods and reaching the oil hole in followers to lubricate the cams. It is a long way with flying pushrods, rockers and all to fling any oil off before somehow finding the badly placed follower oil hole. So lasered the follower hole shut and take care for good supply through the cam spindles instead.
Even spray bars for cam oil suply don´t work as great as intended, better get oil from within cams and out the holes at start of valve lift.

Vic

Yep, it make sense to me to have the cam nice and oily especially with a lack of zinc in oil (I hear).
Just gotta figure a way to get them hole in there!
thanks, Mike

 

[Mike Davies]

In case your cams are not drilled, have them spark eroded as drilling might be traumatic. The holes should be on the base circle just before lift begins, see photo below.
Bronce bushes should be allright when getting the right stuff. I have CuSn8 2.1030 bushes in most places where bronce is recommended. This type is like phosphor bronce but no phosphor content. Make sure you got min. 1 thou but below 2 thou clearance on spindles.
BUT you have to do a mod for safe oil supply to the holes even when a bush has walked. So not just drill the cam holes through the pressed in bushes as holes get blocked when bushes walk. I´d have a look at grooving the bushes along the axial direction where the holes were drilled , groove dremeled in i.d. of bushes - plus another radial groove turned in in o.d. of bush where the oil holes are meant to go . So oil can exit the spindle supply any time for lubricating the cam follower, not just when oil holes in spindle and camshaft bushes line up in a very short moment. Ot did I miss something from remembrance ??

Vic
View attachment 47859

Very interesting. Getting the dremel out is easy enough but not sure where to get spark eroding done around here. I'll check it out, thanks, Mike

 

[Cyborg]

Very interesting. Getting the dremel out is easy enough but not sure where to get spark eroding done around here. I'll check it out, thanks, Mike

There are a few places in town that do it. I have a list somewhere.