Elmer’s VR75 engine

[GeoffTParticipant @geofft]

Hi all

Am currently building Elmer Verberg's VR75 vertical engine. On the cylinder body the two ports are shown as 1/16" x 5/8". This seems too wide, I think it should be 1/16" x 3/8". Anyone else built this engine and can confirm the size?

Thanks

GeoffT

[GeoffTParticipant @geofft]

[Martin ConnellyParticipant @martinconnelly55370]

The drawings I have show two ports of 1/8 x 5/8 and a central exhaust port with three 1/16 holes at 3/32 spacings. Looking at the valve it has a central recess 1/4 x 9/32 and outside dimensions of 13/32 x 7/16. This seems odd until you see that there is a valve plate that goes between the cylinder and the valve and that has got 9 x 1/16 holes at 3/32 spacing. I think the dimension on the drawings I have look as though they will work out fine.

Martin C

Edited By Martin Connelly on 04/07/2022 16:27:44

[JasonBModerator @jasonb]

They don't really need to be any wider than the overall width of the sets of 3 holes in the valve plate, I'd probably still use an 1/8" cutter as it's a bit more robust than 1/16"

Probably meant to read 5/16 wihich gives a bit to play with over the holes which would total 1/4" The 5/8" is clearly wrong when compared to the 3/4" dimension for the valve chest studs

Edited By JasonB on 04/07/2022 16:31:53

[Martin ConnellyParticipant @martinconnelly55370]

 

I also think it should be 5/16 not 5/8. The outer dimension of the 1/16 holes and the 3/32 spacings is 1/4" This is slightly less than 5/16 so there is a bit of leeway in the cylinder ports allowing for some mismatch between the cylinder and the valve plate.

Martin C

Edited By Martin Connelly on 04/07/2022 16:40:13

Edited By Martin Connelly on 04/07/2022 16:41:12

[GeoffTParticipant @geofft]

Thanks Jason and Martin, that seems to make sense.

5/16" it is, also will probably go with 1/8" cutter as per Jason's suggestion.

GeoffT

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