Ron Chernich statement about Morton M-5 gear case??

Home Model Engine Machinist Forum

Help Support Home Model Engine Machinist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


Well-Known Member
Oct 6, 2008
Reaction score
Ron said the following []:
Screenshot 2024-04-23 at 8.39.12 PM.png

That does not seem to make sense in light of the drawing:
Screenshot 2024-04-23 at 8.34.44 PM.png

Screenshot 2024-04-23 at 8.35.05 PM.png

The Morton M-5's five cylinders are at 72° intervals with the #1 cylinder at top dead center. It seems to me that the drawing shows that the 10 tappet guide holes are located symmetrically ±20° about the cylinder centerlines. How did Ron end up with left-right asymmetry? Or is he saying the 5 larger inlet hole bosses on the casting are not as per the drawing?


  • Screenshot 2024-04-23 at 8.35.35 PM.png
    Screenshot 2024-04-23 at 8.35.35 PM.png
    57.3 KB · Views: 0
Ron says there was an error in the castings so they don't match the drawing. Sounds like he picked the out of place pipe boss as his starting point for both sets of holes which does not then place the tappets equally to either side of the cylinders

If you also have the MEB drawings they set the tappet holes 19deg either side. So they are not quite inline with the pipe holes.

Pipes are 52 deg and then 72deg spacing. Guides are 72 less 19 = 73deg so won't line up by 1 degree on the MEB drawings. But you would need to check the pipe spacing suits the bosses of your casting unless you are making from scratch
Last edited:
±19° would be closer to having intake/exhaust overlap, which might be an improvement. I'll have to dig out the MEB plan set (which I have) and see what's up with those as compared to the Morton plans. I was going to index the gear case from the top, so my tappets would have ended up symmetrical, and, if the pipe bosses are off the pattern, I would have found out quickly, I think. No harm no foul so far. I only ended up down this rabbit hole because I wanted to see whether any plans contemplated bronze tappet guides.

Latest posts