Camshaft end play

[Sneezerap]

....Ideally size the head so that it locks against the front of the cylinder block and can't come loose.

Absolutely not!! That means you can't tighten it or refit it if there's an oil leak up the thread without removing the cylinder block. It might be how Austin designed it to be with the square headed peg bolt (AKA The 'Teutonic Bolt') but to replicate that idea is not a good move. Tap through into the camshaft bush and make your new peg bolt such that it fits down into the bush without touching the camshaft. Socket head or hex head are both fine. A turn of PTFE tape around the thread, a suitably sized Dowty Washer (or fibre washer and goo if you must) under the head and tighten down. In the unlikely event that you get an oil leak, at least you can refit and/or tighten insitu. 

Steve

Thanks for the replies regarding my problem with the camshaft moving forward and back. I checked the movement again and the distance is a huge 1/8". The photo of my block shows the bushing protruding out of the crankcase while the example of one of the members has the bushing recessed into the block. It also appears that the photo of the example bushing may have more than one locating hole for the retainer bolt. Is the bushing the only part that keeps the camshaft from moving forward?

[Stuart Giles]

"It also appears that the photo of the example bushing may have more than one locating hole for the retainer bolt. Is the bushing the only part that keeps the camshaft from moving forward?"

The example bush shows the the locating hole for the bolt that goes through the top of the crankcase; the other hole lines up with the drilling that goes to the oil gallery.

"Is the bushing the only part that keeps the camshaft from moving forward?"

Basically yes. The bush is trapped between the rear face of the camshaft gear and a thrust face on the camshaft directly behind the camshaft's front bearing surface. When fitting up, any excessive camshaft endfloat is reduced  by lapping the gear onto the taper, and increased by skimming (or very carefully filing) the front face of the camshaft bush.

[Chris KC]

I'm not sure why you'd want to remove it if it's assembled robustly in the first place.

[Sneezerap]

I'm not sure why you'd want to remove it if it's assembled robustly in the first place.

I do not want to remove the bushing or the camshaft. The camshaft will move forward and backward when the timing gears are installed by 1/8"  Thus far it has destroyed the timing gears plus the fiber gear on the end of the generator/dynamo. Someone, apparently,  overhauled the motor about 30 years ago and did not do a bang up job. Motor ran well until the fiber gear end up with missing teeth.  If I can stabilize the camshaft, I will have a good running motor.

[AustinWood]

From the picture it looks as though it is the locking bolt that is the problem and the bush is probably moving with the camshaft rather than the camshaft moving in the bush. It is possibly both. The locking of the bush must be fixed before the movement of the camshaft in the bush can be assessed.
I agree that the locking bolt should be hex or cap head. I've had too many leaking through that bolt in the past. I have also had the camshaft feed block necessitating removal of the bush. It's simpler and easier.
Tap 5/16" BSF into the bush to make sure it's firmly locked. The original peg system is poor.