Centaur Gas Engine

[Maurice Cox 1Participant @mauricecox1]

[Maurice Cox 1Participant @mauricecox1]

I have got involved in finishing a second hand Centaur Gas Engine, that a friend has bought. Has anyone out there built one, using the alternative timing gears supplied by A.J.Reeves. The centre distance of the gears is approximately 9/32" greater than shown on the drawing. This of course will alter the geometry of the valve gear. Also, it will be necessary to cut a crescent shaped cavity in the cylinder support casting, 1 1/4" long by 9/32" deep, to accept the larger diameter gear. I could reduce the cavity size to 15/16" long by 1/8" deep, by packing the camshaft out sideways by 1/8", but this will change the geometry still further. Any input about this would be most welcome.

Regards Maurice

[JasonBModerator @jasonb]

Maurice have you read the recent article in ME about getting one of these to run. There is a problem with the gears as the illustrations that went with teh article including the one on teh cover have the gears the wrong way round. It also details carb modifications.

Just looked at a couple of build threads which mention cutting away the base casting even for the original gears. No mention of different ctr distance, the inlet should not be such a problem just a longer rod but the exhaust would really need the arm cutting off at the pivot and the angle opening up so the cam follower comes 9/32" lower and the shaft brackets also lowered by 9/32"

 

J

Edited By JasonB on 20/06/2015 08:03:26

[MichaelRParticipant @michaelr]

Maurice. I used stock gears supplied by HPC Gears, **LINK** the large gear is 32DP 24 teeth and is 1.123 overall dia, I had enough metal on the side shaft bearing housings to allow the large gear to fit without having to machine the groove in the engine frame casting.

This setup does alter the centre line of the side shaft but very little and the valve gear is as the drawing, what it does alter and it doesn't effect the running or the valve settings is the inlet push rod is slightly off square.

[Maurice Cox 1Participant @mauricecox1]

Thanks for the feedback gents. The HPC gears website is very interesting. This would seem to be one problem solved. Just got to solve the rest!

Thanks again Maurice

[Maurice Cox 1Participant @mauricecox1]

Hi Stick, I've just had a closer look at the list of gears from HPC Gears. As I see it, to achieve a ration of 2:1, the 24 tooth gear you used would have to be used with the 12 tooth one. This has an O.D. of only 0.53". How did you accommodate this on a 1/2" crankshaft ? Is the shaft smaller than on the drawings?

Thanks for your help

Regards Maurice

[MichaelRParticipant @michaelr]

Maurice. The crankshaft has a portion reduced to 5/16" dia for the 12 tooth gear, my drawing does show this reduction, the other thing you may have to bevel the crankshaft bearing just enough to clear the 24 tooth gear, I think you will see that on the above picture.

Part Number for HPC Gears H32-12/ RH H32-24/RH

[Maurice Cox 1Participant @mauricecox1]

Thanks for the explanation Stick, I'll have to see which route the chap who actually owns the engine wants to go down; you have been a great help.

Regards Maurice

[Author]

Posts