Modified Cam Followers

[Paul N-M]

Hi All,
Tim Reynolds posted some photos several years ago on the old forum which are now unavailable. These were of modified cam followers and asymmetric if I remember correctly.
Tim if you are reading this I would appreciate it greatly if you could repost them on the new forum as this is something I am currently investigating.

Many thaks,

Paul N-M

[Parazine]

Here's the reprint:

--1016489--Re: Cam followers
When I finally got my first Chummy on the road in 1989, I was staggered by the performance. It had a big valve block and modified cam followers among other mods. A few years later, I removed the cam followers to use in another engine, and I'm sorry to say that I'm only building that engine up now!
Anyhow, the point is that without the magic cam followers, the engine lost all its sparkle and ran very poorly. Here is a pic of the offending items, I reckon they're flat on the bottom!

Roger French subsequently pointed out that they were very similar to the ones supplied by his father and they were not to be used with a modified camshaft!

I can report that I finished building up the replacement engine for the Chummy some time ago and it is a quick motor, especially coupled with a 5.375 axle.

Thanks, Tim Reynolds

[Paul N-M]

Thank you very much.
Very interesting.

[Tony Griffiths]

Are the flat followers causing the valve train to be noisy - or is there no difference?

[Alan]

I always meant to do a proper analysis of what happens, but essentially the flattened tappet causes the valve to open and close more rapidly and possible earlier and later, too. The acceleration forces are high and, yes, there will be an increase in noise and in wear rates. Mostly, with standard cams I use tappet blocks ground with a 2inch radius - it’s easy to produce that on a lathe but H&S might disagree.

[Nick Lettington]

I have often wondered if, using the brass cam follower guides from a very early block,  it might be possible to manufacture and fit some fiendishly clever cam followers like those a certain Mr Chapman made for the Ford 1172.

There's probably a good reason why no-one has.

   

[Alan]

There is a very good reason. There are at least two people who will grind you a cam that works with standard tappets more cheaply than doing complicated modifications. I’m not saying Chapman was wrong, merely the cam grinders I’m thinking of probably weren’t born yet.

[Ruairidh Dunford]

Tim's followers, are very like a variety produced by Cambridge Engineering, only they were drilled too.

[Ruairidh Dunford]

       

[Parazine]

Are the flat followers causing the valve train to be noisy - or is there no difference?

It's a bit noisier with these followers but not excessively so. The engine has done about 5k miles since I built it about 4 years ago and the noise has remained constant.