Augusta progress

[Mikenoangelo]

Yes the pivot is the bolt nearest to the grinding wheel and is placed at the radius (21.7mm) of curvature of the rocker face away from the grinding wheel so moving the pivoted lever allows grinding to follow the proper curve of the rocker. The stud on which the rocker sits is placed at 38mm from the centre of the rocker cam which is the radius of the rocker from the rocker shaft to the mid point of the rocker cam face.

I lapped the cams manually, starting with the 4 cams to the back of the camshaft which are aligned in pairs so that the lap stone straddles two cams which helps keeping it all aligned. The other set of cams are not aligned so a bit more care was needed. The action was a combination of rolling the camshaft in the lathe and movement of the stone. The wear on the cams was pretty much a series of grooves so I could lap enough to remove the grooves but not enough to change the profile. Probably only a couple of thou were removed.

All this was following Morris Parry's ideas for which I am very grateful.

Mike

[Kari]

I like the rocker facing kit. This will be good for very worn rocker arms. For less damaged rockers I have been using a drill press with a grinding disk covered with a fine grit emery cloth, and then polished to a smooth surface.
The damage on the camshaft looks to me as exessive valve clerarance or bad lubrication or both. Many years (and miles) ago I have set the valve clearances on my motor from factory 0,25 mm to 0,10 mm inlet, and 0,15 mm exhaust valve. This gave a reduction in noise and therefore in wear and so far no ill effects have been noted.
Regards   Karl

[Mikenoangelo]

As we say in the UK - many ways of skinning a cat! Probably not allowed to use that expression now.
I intend to polish my rockers now they are back to the right profile - the grinding wheel is a bit coarser than I would like. Probably by putting emery paper on the side of the wheel or by your system Karl.

The rocker clearances were not too great and it ran without much noise so I think the wear was due to poor lubrication as the rocker shaft had a lot of rubbish inside which took a long time to remove washing with kerosene and use of the airline. I've bought a Mann spin on filter and a block of aluminium to make the mounting to replace the Autoclean.

Mike

[DavidLaver]

To understand with the drill press - by "plunging" did the rocker rock against the elastic?

Can also see that's no ordinary drill press...  Was it made by Heusser or used by them? 

[Mikenoangelo]

Here’s a curiosity. The 8 small “steam holes” connecting the block to the cylinder head have a copper insert, presumably put in with a small countersink to the face of the block, which reduce the hole from 5mm to 4.5mm. The oil feed hole which supplies the rocker shaft and rockers has a similar insert, also reducing the diameter from 5 to 4.5mm.

Has anyone else seen this feature on an Augusta block? The inserts projected about 0.25mm above the face of the block, possibly to compress the gasket around the holes, all of which are very close to the cylinder bore. The projecting parts were very uneven so I levelled them off in order to check the flatness of fit of the head to the block with a feeler gauge. Was this a mistake? As some Augustas (Belnas?) do without the small water holes the reduction of bore from 5 to 4.5mm is of no consequence but I wonder if it does matter for the oil feed to the valve gear and does the now missing projection matter?

Mike

[Kari]

I have seen this kind of repair before. The edges of the bores can corrode, causing leaks. An insert like this can save the block or head. IMHO the bores should not be closed complete, but a bit smaller diameter should be ok. They should be flush though. From factory the bores were 6 mm.

My drill press is a bit unusual I guess, as it has a sliding vice installed, which can be replaced by a flat plate. I bought it surplus from the Swiss Air Force in about 1985. I has done very good services in all the years. I think it's 60 years old or more. The manufacturer was MOSER AG, Heusser was the vendor.  I did grind the rockers by up-down movement against the rubber band. At one time I made a new trottle shaft for a Zenith carburettor and did cut the slot for the butterfly on the drill press, moving the vice by hand very carefully. The tools behind the drill press are back up tools. The everyday toolbox is on a trolly.

Regards  Karl

[Mikenoangelo]

Oh heck I'm going to have to tidy my workshop!!

Mike

[frankxhv773t]

Mike, you could just claim that you are recreating the Scuderia Manning look.

[Kari]

I must admit that I did tidy the shop before taking the photo.

Karl

[Mikenoangelo]

 

Mike

[GG]

Is it fair to say that the radius on the rocker arm pad was not so difficult for them to make at the factory, but is a bit of a challenge to refurbish later? I could imagine most repair shops simply grinding and smoothing them, without attention to the radius. Thoughts?

[DavidLaver]

Like so much of the work we get to enjoy here am sure many wouldn't bother, or would give it a quick go with a bit of emery paper, but isn't it lovely to see it done carefully?

In terms of "does it matter" the radius defines valve timing, a little bit.  One of the first tuning mods for an Austin 7 is to regrind the followers to a "flatter" profile to extend valve opening time.

[Mikenoangelo]

Yes the profile does matter. Many years ago Oliver Langton the speedway rider, VSCC Member and vintage RR enthusiast was building a 20hp Rolls Royce special and planned to exploit the very wild looking cams which went with roller tappets by swapping the rollers for profiled followers. Sadly that project was never completed. Oliver was the chap who found and restored the oldest surviving RR, a 1904 10hp, the only RR eligible for the Brighton Run. I suspect going from a roller to a flat follower would be too much but a good mathematician could probably work out something in between. No inappropriate jokes about Rollers please.

The kit which Morris devised for grinding the follower is very simple - I suspect the thought process was the hard bit.

Mike

[Mikenoangelo]

Still awaiting some gearbox bits from HB Bearings - frustrated on the reassembly of the box but this week I made an adapter to take a modern screw-on filter in place of the Autoclean, hoping to maintain a clean flow of oil to the camshaft department. Dale Hicks kindly sent some drawings and the trusty but aged Beaver milling machine did the job. Some concentration is needed as it is very easy to confuse the in and out ports from the crankcase to the adapter when drilling holes to form the oilways inside the adapter. Photo 75.

When I took the cylinder head off I did not choose to remove the timing gear from the crank or the timing chain but found that a block of wood placed on top of the block can support the tiimng chain and allow the engine to be turned without entangling the chain which just turns round the block of wood like a sprocket. Photo 76

Mike

[neil-yaj396]

Very impressed with your adaptor Mike. What car/cars is the cartridge for, and what made you decide on that size?