Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[Kevin49]

Anyone got any ay ideas about the positioning of the ports on a Puffin Engine, I had problems with mine , it didn;t run very well, and felt that the distance between the ports on the pedestal were too great for the rotational movement of the cyclinders, Have now re machined them, the engine run fine but it won't start, are the prts too close together.

Advice and assistance would be grategfully receied.

Kevin

[Bunkerbarge]

Kevin, From what I know of the quality of Cheddar engines I would be very surprised if the ports ever required re-machining.

The best way to check would be to draw a simple constructional diagram with a circle of a radii of the crank throw with a tangent touching it and passing through the cylinder pivot.  You can also draw an arc about the cylinder pivot point and from these lines and the distance of the port in the cylinder from the pivot point you can mark off exactly where the pedestal ports should be.

Unless someone has played with it in the past I strongly suspect that the original positions were the correct ones and the fact that the engine now does not start possibly has something to do with this.  It may well run, although not very well, with the ports slightly out but starting it might be a bit more of a challenge.  You may even find that one cylinder is now out and one is OK so the engine is actually running on one only but it won't self start on one cyliner.

If the port positions have now been moved you must determine the exact position from an accurate sketch and ensure that the pedestal ports match this.  If they don't then they need correcting but if they do then you will have to start looking for tight spots, piston ring sealing or correct sealing of the port faces etc.

[HS93 (RIP)]

has  someone made a new crank for it ? I have never heard of any problems like that with cheddar products, I have several examples of that engine and no problems, can you tell us a bit about it's history was it bought as a set of castings ?

Peter

[Underpressure]

All Cheddar engines were CNC manufactured and assembled by hand. The more complex engines like the V4, Proteus and Gemini were factory run before dispatch, but I don't think the Puffin or Pintail were tested.

There is a very slight possibility that this engine was made badly, as anything that can be machined can be mismachined, but in my experience it would be a first.

Engine history would be useful, as would photo's of the cylinder faces and the faces you believe have been machined wrong.

There is always the possibility that your engine is an Isis. This was a kit of unmachined parts that made up into a Puffin engine.

Neil

[livesteam]

Hi!
Is there anybody who could provide a scan of an explosion drawing of Cheddars Puffin engine? I tried at Clevedon Steam (Jerry was very helpful, thanks!)  but without success.
Thanks!
Kaspar