Newbie, trying my first engine, ring question

[coyotebgone]

The plans do not define the ring sizes. whats the rule of thumb, make the ring od the size of the jug in its relaxed state, before heat treat. And the ring ID a few thou bigger than the piston groove
diameter?

 

[Brian Rupnow]

Coyote--to save yourself a lot of work and grief, use a Viton o-ring. You only need one ring, with a nominal outside diameter of 7/8" and a nominal 1/16" diameter cross section. (They actually measure 0.070" cross section). Use a 3/32" parting off tool to cut the ring groove, and make the groove 0.057" deep. Do a plunge cut, straight in and out so the groove width will be very close to 3/32" wide. The top of the ring groove should be 0.125" below the top of the piston.---Brian

 

[Nerd1000]

This is for a Webster engine?

For mine I used a 0.8mm ring groove. Rings were nominally 0.8x0.8 in cross section, in practice slightly thinner so there is clearance in the groove. The groove needs to be a little deeper than the ring, I think I cut mine 1mm deep. Ring OD is the same as the cylinder prior to tensioning.

I broke the rings using my fingers and the milling vise, then tensioned the rings using a torch with a circa 3mm mandrel in the gap, but the heat treatment didn't relieve all the tension so I ended up with a gap of a little over 2mm. Made 4, selected the best two to use in the engine. Attached is a photo of the 'spares' for reference.

 

[a41capt]

I am new.May I ask Webster engine is Westbury Whippet Flathead Engine?

I found a article about Westbury engine.
https://www.enginediy.com/blogs/eng...ne/westbury-whippet-flathead-engine-enginediy

The Webster is a greatly simplified, open crank internal combustion (IC) engine. It is designed as a first IC engine for knuckleheads like me to attempt. I got lucky and actually produced a runner!

if you’re looking for a first IC engine, I highly recommend downloading the free plans and diving in.

Good luck!
John W