Jump to content
DerekM

Oversized engine mount holes?

Recommended Posts

About to start rebuilding an old racing engine and noticed immediately that the casing has an enlarged engine mount hole on one side, where the engine mount can slide in and out with little to no pressure. There’s enough clearance that copper compound or similar would probably not do anything. Is the only option a copper shim or has anyone seen anything like this before? 

4E8134BB-5C4B-4BF4-A44A-26DC1561D0C4.MOV

Share this post


Link to post
Share on other sites

Wow! And they are tight on the opposite side?

It would be tough to get a shim in there as it is such a tight fit and the shim would have to be thin so it would probably get all screwed up during the install. 

Share this post


Link to post
Share on other sites

What kind of mounts are they? Might be worth it to spec a few different ones and see if any are bigger than those. I am sure there is variance between Casa, BGM, SIL, Scootopia, etc.

Share this post


Link to post
Share on other sites

I’ve got a friend who has the same issue with a very high mileage jet 200 case. 

The mount will slide in by hand. He plans to have the cases repaired with weld

and machined. 

He has regularly driven this engine since the late 80s. 

 

The mounts and cases are designed to have an interference fit to them. 

Share this post


Link to post
Share on other sites

There’s a lip at the end so they must have been installed or removed incorrectly, causing damage to the cases. I’ll get them welded up and machined back to fit. 

8DF5489A-1656-4C0B-BE20-284E5AAD6ABA.jpeg

Share this post


Link to post
Share on other sites

I think it will be solved with different make of silent blocks. It had silent blocks in it that were tight, right?

Share this post


Link to post
Share on other sites

The old mounts and the bgm mounts are the same size roughly 36mm, so I took some measurements of the case and it’s been widened in an oval fashion approximately .3mm causing the loose fit. It appears this is due to corrosion and build up on the mounts, which elongated the softer alloy of the case during extraction. I’ll need to add some material to the case to fill the gap. 

Share this post


Link to post
Share on other sites

Welding and machining a few thou will be expensive... 

Maybe a smear of jb weld until they egg out enough that jb weld will not hold... 

Share this post


Link to post
Share on other sites

I also have a jet 200 motor with same issue, maybe its a serveta issue or they used bigger mounts later down the production line? Mine is a late serial number 5598xx

Share this post


Link to post
Share on other sites

Several years ago there was a bad batch of Casa made silent blocks that were made too small and fit quite loosely. Wouldnt be out of the question to try another set.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...