I had trouble seating the pushrods so I took the head off to start again. Looking inside the head I was surprised to see how rough the casting was. It looked like the tunnel hadn't been machined far enough and there was a ragged ridge sticking out about half way down, more pronounced on one side than the other. Anyway, I filed it down and the head went back on quite easily. I don't think I'm suggesting that the ridge was stopping the pushrods lining up but it didn't look right to me. Am I being over critical of something that will never be seen or are they all as rough as that?

They often do seem to be very rough and I've 'dressed' several sets. It can't be a good idea to have irregular rough edges on castings .

I think that it's worthwhile to tidy up any surfaces. Inside or out.

Not only were my pushrod tunnels very rough but they also had a fair bit of sand embedded in the oily gunk lining them. Pretty sure my engine had never been apart which makes me think it was casting sand that never got cleaned out!! Anyone else seen this? I cleaned everything out really well upon reassembly but was pretty shocked at how much nasty crud was in there. Potentially very damaging crud.

I'm pretty sure that, except for where the pushrod tubes fit, the pushrod tunnels are left "as cast". They certainly shouldn't still have core sand in them, though! The running clearance is more than adequate, but it might be tough getting the bigger diameter ends through on assembly.

Note that this comment was dug up from 1968 memories, so I could be full of sand (or another 4-letter word starting with an "s").

frankdamp wrote:I'm pretty sure that, except for where the pushrod tubes fit, the pushrod tunnels are left "as cast". They certainly shouldn't still have core sand in them, though! The running clearance is more than adequate, but it might be tough getting the bigger diameter ends through on assembly.

Note that this comment was dug up from 1968 memories, so I could be full of sand (or another 4-letter word starting with an "s").

One of my tunnels had a lot more sandy crud than the other and the cam follower was also more scored on that side making me think that some of the sand was washed down on the cam. I was not impressed! I think somebody forgot to clean out my tunnels at the factory.

frankdamp wrote:Note that this comment was dug up from 1968 memories, so I could be full of sand (or another 4-letter word starting with an "s").

All recollections from 1968 much appreciated, complete with sand or s - s - s - something else

Gday Berticus, looking at a photo of my Commando,s head I posted on "Installing Pistons in Cylinders" I noticed the tunnels are rough aswell! Mmmm...a little bit of fileing to do for me. Thx regards Foxy