ORIGINAL: flybyjohn
I have an itch to make a diesel head for a como 90, supertiger 61, or thunder tiger 46. I don’t know which one will be first but just want to try diesels out. If I get the 90 to run good, I will probably put it in my Corsair. I have looked at quite a few photos and plans for different heads and have recently seen the article in fly rc magazine. All the designs I have seen thus far have an o-ring seal on the contra piston. I have not come across a picture of the parts to the davis diesel head yet but they don’t seem to have any replacement o’rings on their site, so I assume they don’t have them in their design. Does the diesel conversion head need an o-ring seal or will a well fitted contra piston work just as well?
Is the Thunder Tiger the Pro 46 with ball bearings? They work well as a diesel.
But you have another option open to you besides lapping a contra to fit or using viton O rings, and its the simple use of high temperature silicon tubing show here.
The flier who designed this head stated that he got a years worth of hard comp flying before replacing the tube, and replacement is very cheap and quickly done.