Glad to see the head arrived safely Hobbsy ... upon reflection the package was a little "small" . I had concerns it may have "slipped through the cracks" somewhere along the line and been lost in the mail.

Your advice on using a 4 mm grub screw for head tensioning is something I will remember. Make sure you locktite it once you are happy with tension. I have lost more than one of them in flight [:@] because I forgot to do that. You would have noticed the brass stopper in the recess which prevents the bottom of the grub screw from burring the threads on the contra-piston adjusting screw.

In operation you will see a little oil leakage past the contra, not a lot, but a couple of drops per run. No viton rings on these. I have never experienced the contra falling out of the head, thank goodness.

If you want the original instructions, fuel mix recommendation, and parts list for the .20D, PM me your address again. I will photocopy and air post them to you. Or maybe Martin can, if he has them.

I am overhauling my .20D at the moment. After over 10 years of on-and-off use, a warm crockpot antifreeze bath is in order. I have new in packet gl*w and diesel heads for it, which I bought eight years ago.

On the original .20D, there is a non-removable (shrink fitted) restrictor insert in the tail pipe of the silencer. Presumably the intent was to narrow the outlet to help with back pressure (maybe for stable idle performance?), or in line with the theory that model diesels are happy with a more restrictive exhaust set up (?). On the diesel silencer the usual pressure nipple was replaced with a hex head brass blanking screw.

However, I have run my .20D with a standard Irvine .20 silencer. I destroyed the original that came with my .20D in a bad crash; and a gl*w spec replacement was all that was available as a spare part. I did not notice any degradation in reliability however I also used a small size exhaust deflector elbow to put back some restriction. I salvaged the hex head screw from the written off silencer and installed it on the gl*w spec silencer. I have not tried silencer pressure.

I also believe the barrel on the carb on mine is of a narrower bore than the standard gl*w spec Irvine .20 carb ... it certainly looks small. Fuel draw without pressure is not an issue.

I am looking forward to your reports on throttling performance.

I might email JustEngines to see if any piston and liner sets are still available for these engines. I don't hold out much hope though, the engine is now long out of production.