Woo who (3)

[Brian Parker]

‘Adjusting the tappets’ goes back to the time when the valve clearances on many side valve engines were set by means of an adjustable tappet type cam follower, the adjusted tappet acting directly on the valve.
A true cam follower is shaped to accurately follow the cam profile. A flat faced ‘cam follower’ is a tappet.

To be pedantic, you can only adjust tappets when you have an engine with adjustable tappets otherwise you just set the valve clearances.

It could be a lot worse, how about a single cell battery.

[Martin Harris - Moderator]

That would be fairly unique....

[Tony Jones]

Posted by Bob Cotsford on 13/02/2012 13:19:32:

Doesn't the cam in an ohc engine act on a bucket, which both holds the shims and takes all the side loads?

 

edit - apart from the old Cavalier/Astra etc engine where the OHC cam acted through a rocker which wore out every 60k miles.

Edited By Bob Cotsford on 13/02/2012 13:21:00

You are absolutely right. I stand corrected.

 

Regards

[Tony Jones]

Posted by Martin Harris on 13/02/2012 13:16:15:

All I'd say is that I've never seen a tappet in a parts list and the usually accepted term where it's used is "adjusting the tappet clearances" which might fit in reasonably well with the Wikipedia description if we disregard the worn aspect - there will always be some noise generated. The part referred to in Tony's post is generally listed as a cam follower in my collection of parts books (to the best of my recollection).

I'll go with that Martin. I personally always use the term cam follower because that's an exact description of what it does. However, an number of engine manuals also call this part a tappet as the diagram shows. But what it isn't is the rocker arm or the screw that is used to adjust the valve clearance. Yes?

 

Regards

[Martin Harris - Moderator]

Posted by Tony Jones on 13/02/2012 14:07:53:

But what it isn't is the rocker arm or the screw that is used to adjust the valve clearance. Yes?

 

Can't argue with that!

 

Really though, at the end of the day (or even halfway through the afternoon), we all know what we're referring to when we use the term.

Edited By Martin Harris on 13/02/2012 14:36:23

[Peter Beeney]

Can we include the Ford side valve engine as well? The E93A I think it was called, or maybe that was the car? The ‘Pop’ , - Popular, with the 1172cc ‘Ten’ engine, and the Anglia, 993cc ‘’Aight’. These didn’t appear to have any adjustable tappets at all, to adjust the clearance, if was too wide you just had to grind the valve in a bit more, and I can’t remember what happened if it was too close, ground a bit off the valve stem perhaps, although that sounds a bit harsh. To get the valve out there was a special punch that fitted round the valve and you knocked the guide out in two halves. I suspect there would have been some wildly varying clearances at times!

PB

[Brian Parker]

Peter,
Ford produced a special jig to enable accurate grinding of the valve stems if the clearance needed increasing. The stem was mushroomed and if I recall correctly ran directly on the cam, not via a tappet.

Problem was that the split guides were easily knocked out from the top using the special tool but not quite so easily refitted from below.

I believe the early V8 engines used the same method.

Very crude by today’s standards.

I was introduced to motor vehicles at a very early age….all so long ago….but what a variety!

[Peter Beeney]

Yes, it all began to come back to me, too, Brian, slowly! I seem to remember we helped the valve guide refitting process by giving them a really good cleaning on their mating surfaces by briskly rubbing them on some course wet and dry on a flat surface. I seem to remember a cam follower, a cylindrical type, that you could pull right out, but that may have been on something completely different. I certainly remember the dummy valve guide, though, for grinding them in. Hinged in two halves, so you could take the valve out, and ball bearings in the walls for the valve to run in.
Now you mention it, I remember something about the jig, but we didn’t have one. But we did have a nice valve re-surfacing grinder, and a re-seating tool, also a grinder, but I couldn’t touch, only watch.

I don’t ever remember seeing a side valve V8 taken apart, but they were fitted in some of the smaller portable gen. sets of the time, 1950’s. They had big 18mm spark plugs, with the HT lead held on with a brass terminal nut. My electrical mentor at the time, I was young once, could lay his arms across one bank of 4! When it was running! He usually had to be talked into it though, and it always left him a bit startled. But he could grab any live mains cables with impunity, without batting an eyelid. He must have had a very dry skin. Or thick! He did finally retire, in good health.
I always had to clean the plugs and points, and again I’m pretty sure I’m right in saying that there were two distributors, located at the front, down near the crankshaft pulley. That was always a bit of a bind.
Fortunately it wasn’t long before the diesel sets started to come on the scene.

As you rightly say, all a very long time ago now. … but what an adventure, too. I couldn’t wait to get into it… ….I must have been mad!

PB