Annoying knock from camshaft front pulley area

[Ian Williams]

I agreed Dave, quite why Austin moved away from the positive bush location they used on the Mag engines is a mystery to me as well, it was probably considered a cost cutting exercise but I cant see how.

[Lowbarn]

Many thanks for all the advice.
Very helpful to new Austin 7 owners!

I’m now struggling to remove the camshaft pinion gear.
End float movement is about 3mm!

I’m now tuning that Alan’s reply above is probably the most sensible approach - engine rebuild.

It seems odd to me when everything internal looks in new tip top condition, yet the camshaft looks like a 90 year old original.

Regards
Richard.

[Austin in the Shed]

It is much easier to remove the gear with the cam out,best in a press,leg type pullers can damage the rather fragile cast iron teeth in my experience.
Mag engine owners more so as the force required to break taper can result in the center breaking out of the gear.
Austin material quality and machining was top class and providing the engine has been fed with reasonable quality oil the camshaft and followers will run a high mileage.

[Hedd_Jones]

As noted, the only way to get a squre headed locating bolt out without taking off the block is using some form of grinder. Been there done that. I now fit fixings with allen key heads there exclusivley.

Once youve got that out, you will be able to get the cam and bush out also without removal of the block, provided you loosen off the tapetts and take all the adjustment out of them - screw the adjuster as far down it will go. You will find that a one lobe will hit one tappet, but a gentle pull will have it out ok.

You will need the sump off so you can catch the centre cam bearing rollers.

The mod as described by Ian can be done when you take the gear off. Put the bearing back in the case, weigh up sizes and tap it something suitable using the case as a guide - you may want to open the case hole slightly to give clearance too, or just tap straight through both. I've seen it done both ways. As above use a cap head bolt. Be careful it isnt to long and nips the shaft before it tightens. And clean off the burrs.

When refitting the cam after your end float adjustment (done by lapping the gear on the cam - go for about 10-12tho clearance before wanging the nut up down to 3tho), to refit you will need to get one of the tappets out of the way, I forget which, but it becomes startlingly obvious as you assemble which one. To give sufficient clearance, use a generic valve spring compressor to lift the valve using the top of the head (not the valve) so as to lift the whole valve and not compress the valve spring. You will need to stick the centre bearing rollers to the cam with grease (which I freeze to make even stickier), coupled with a elastic band around them - this pushes off as the rollers engage in the race, you then snip it off.

I find it easier to do all this with the engine sat on its bellhousing vertically on the bench.

Have fun.

[Lowbarn]

Thank you for the detailed advice.
Having spent the morning fabricating a pinion puller that fits and giving the pinion a lot of pressure, I now understand what your saying above. There’s no way the pinion is departing company with the camshaft!

Im now thinking, bite the bullet and take the engine out.


Strange how, as a newcomer to 1930’s motoring, you have this utopian view of bouncing round the country lanes on a sunny afternoon. When in actual fact it’s really all about a nice comfortable dark, cold and oily workshop!

Richard

[Austin in the Shed]

The taper is very similar to a Morse,as used on lathes etc,imagine if you hammered the two together and think then of the force required to split them.
Think you would be wise to check the whole engine if there is 3mm endfloat on cam bush,something amiss to get that much clearance.

[Charles P]

I find it easier to do all this with the engine sat on its bellhousing vertically on the bench.

Have fun.

Doing it on your back, inside the crankcase, trying to keep the rollers in place and wishing for a third hand, is undoubtedly possible but not advisable if anyone within 100 yards might be affected by the resultant extremely flowery language. 
I reckon it would be quicker to remove the engine, and possibly mentally less damaging.

c

[AustinWood]

I always remove the camshaft gear using a 3-leg puller. I have done this many, many times.
The trick is not to try and pull it using brute force. That will break the gear.
I fit the puller, and sometimes have to remove one of the bolt holding the front main bearing retainer.
Do up the puller firmly making sure that it is properly lined up and straight. DON'T MAKE IT TOO TIGHT.
Strike the centre bolt of the puller firmly with a hammer.
I find the gear just falls off.
The reason it works is that the camshaft is located by the gear bearing on the front bush. It is otherwise free to move back. The puller acts as a guide for striking the end of the camshaft absolutely straight.

[Lowbarn]

Things have moved on. I’m about to remove camshaft. I’m taking all the valves out to make the job easier.

Quick query is it possible or even necessary to have the head cleaned? I’m thinking of the water chambers mainly. Combustion side is fairly clean.

Also is it the done thing to paint exhausts manifold with heat resistant black to hide the rust?

Will report back shortly on the camshaft 1/8” end float issue. Retaining pin wasn’t worn so I’m hoping the bush is worn. Would be nice to find the reason for the knocking.
I’m still convinced the crankshaft, pistons and head are in good condition. Although I don’t have the kit to measure the bores there is no visible sign of wear.

Richard.

[Lowbarn]

Didn’t take the valves out in the end. Double valve springs added complications.

Once wiggles out, the camshaft front bush has an oval locating hole. So I’m now very hopeful I’ve found the knock.
I’m going to use Tony Leslie’s bolt replacement idea for the pin.

Hopefully will be on the road for the Centenary at Moreton.

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This is the offending bush.