Hi Guys

The exhaust valve rocker spindle on my cub is loose in the head, it will not tighten only rotates. When I run the engine it moves up a down noticeably at the oil feed banjo end. I guess the head hole is worn, does anyone know of a fix or a good engineering company who can sort it. I guess welding and line reaming to size would fix it. Any ideas greatly received.

Not an uncommon problem this.

Firstly if the threads are clean and undamaged and all the correct washers are in place there should not be a problem.

Sometimes the copper washers are not thick enough to leave spare tightening room (domed nut runs to its limit) on the spindle so the use of an extra copper washer cures the problem. If it still won't tighten, cut a groove in the opposite end of the spindle to allow it to be held with a screwdriver. Need to use a 1mm cutting disc in a grinder for this as the rocker is hardened.

If you've had the spindle out, have you put the correct 3/8" hardened washer on the spindle inside the head at the nut end? If not the spindle will cut into the alloy. The 2 plain and one sprung (Thackeray) 7/16" washers go at the other end.

Stopping oil leaks at the plain end has always been my biggest problem. The 'O' rings are a pain so I use high temp silicon now.

Good luck

In addition to Stickinthemud's reply, another solution is to either obtain oversize shafts (Serco used to do them ) or get yours increased in dia. by having them chromed ( only chrome the worn bits ). To cure the leaking problem, I shortened the shaft by 3mm and cut a 1mm slot in the end - tighten the banjo whilst holding the shaft with a screwdtriver then tap in a 3mm thick aluminium end cap ( use loctite as well if you want )

Edited February 13, 200917 yr by trialsoldtimer

Hi Guy's

You could find the answer to the problem is to look for another head on e-Bay. It could be far cheaper than having the head repared, or the shafts plated, you decide.

Regard's Charlie.

My shafts cost about a 'tenner' to be plated