Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

The Regular Stuff: Chat, Buy, Sell, Off Topic, etc. => General Discussion - Scale Model Gas Engines - Hit & Miss - Throttle Governed - Non-Compression – etc => Topic started by: MadeForThat on November 07, 2022, 12:02:18 pm

Title: Re: Holt H75 wrist pin cylinder wear.
Post by: Fullraceflathead on November 09, 2022, 12:06:46 am
I purchased 1⁄32 thick Teflon sheet from ebay you can take brass tubing the same diameter as a wrist pin and use it as a punch and make small teflon discs to protect the cylinder walls.
Title: Re: Holt H75 wrist pin cylinder wear.
Post by: MasonvilleEngines on November 07, 2022, 07:31:19 pm
Same idea as o-ring, have used nylon washers or sliver of nylon bolt from toilet seat in this application.

Len.
Title: Re: Holt H75 wrist pin cylinder wear.
Post by: rodnoc on November 07, 2022, 12:42:54 pm
When reassembling, center the pin and fill the space on both ends with a slice of o-ring rubber or urethane belting.  That will keep the pin from drifting and contacting the cylinder wall.  The chosen o-ring material diameter should be an easy press fit into the piston, not snug so it bulges out.
Title: Holt H75 wrist pin cylinder wear.
Post by: MadeForThat on November 07, 2022, 12:02:18 pm
Hey all, I know this has been mentioned before, but I am going through my H75 and noted the "scoring" (more burnished in my case) of the cylinder walls from the wrist pins. How have folks been keeping the wrist pins from reaching the walls? I have considered peening the ID of the piston pin holes to trap it, but that will make removal some day a bit more of a challenge. Any recommendations appreciated :)