Camshaft end play

[Sneezerap]

Hopefully someone can help me on a problem with my 1931 American Austin. My motor which is a mirror image of your Austin Seven has destroyed the fiber gear on the distributor.  The timing gears are now also heavily worn. I have tracked the problem down to the camshaft moving forward and backward. Travel is between a 16th and an 8th of an inch. Can anyone advise me what can be done to get the camshaft to stay in position?  Any help would be appreciated.  Thanks:  Arnie

[Ian Williams]

Depends on why it is floating, clearance between the bush and gear should be 2 to 3 thou, if the bush is moving in the crankcase the locating pin can be modified to secure the bush. If you could put up pictures we could probably give you more specific advice on your own engine.

[Stuart Giles]

Welcome to the forum.

Ian is referring to the setup used on the British Austin 7 motor, where the front camshaft bush is retained by a bolt that goes through the top face of the crankcase. Here's a photo where it's visible.



Not sure that the arrangement is quite the same on the American Austin motor if your crankcase looks like this one that i snapped at the Carlisle PA swapmeet a few years ago.



As Ian says, some pics of your motor would definitely help.

[Sneezerap]

Welcome to the forum.

Ian is referring to the setup used on the British Austin 7 motor, where the front camshaft bush is retained by a bolt that goes through the top face of the crankcase. Here's a photo where it's visible.



Not sure that the arrangement is quite the same on the American Austin motor if your crankcase looks like this one that i snapped at the Carlisle PA swapmeet a few years ago.



As Ian says, some pics of your motor would definitely help.

Attached is photo of my motor. My bushing appears to be to far forward compared to your photo. My retaining bolt is also cocked rather than the head fitting flush. I am guessing that when the bushing is further to the rear it prevents the camshaft from moving forward.

I purchased the motor as having been rebuilt about 30 years ago and never run. I am certain that 30 years ago anyone rebuilding an Austin motor would have limited information on how to do the job coorectly

[Ian Williams]

The locating bolt for the bush looks well and truly butchered, the thread in the crankcase will be almost certainly damaged. The best option will be to drill the crankcase thread out, either 5/16" dia or if you have to 3/8" dia, tap the bush and fit a stud through the case into the bush, then place a dowty type bonded sealing washer over the stud a and tighten a nut down to hold everything in place. You will still need to ensure you have the correct end float between the bush and timing gear, I will sort out a picture to make things a bit clearer.

---

  DSC06408.JPG (Size: 179.57 KB / Downloads: 368)

[Ian Williams]

Absolutely correct Nick, I have edited my post especially for you

[NickB]

[Chris KC]

Fully agree with Ian's comments above. The camshaft bush locating bolt is one that's well worth taking time to get just right. On my Nippy I had the original hole plugged and re-drilled to provide a sound joint. Ideally size the head so that it locks against the front of the cylinder block and can't come loose.

[Hedd Jones]

Good lord no!. Make the bolt iut of an allen key bolt. If you ever need to disturb it again its easy. Say to take the camshaft out. As is tightening it if it comes loose.

[Steve Jones]

....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