3C Engine Install

SandPebbles

SandPebbles

Junior member
Location
Madison, CT U.S.A.
After being apart for several years, the engine was finally reinstalled in the frame of my '74 3C.
I used a method I've read about (and seen used) here on the forum and laid the engine on the primary side then
placed the frame over the engine.  It worked a treat and took me about 60 seconds to complete.

I then slid four bolts through the four rear mounting lugs and placed nuts on them finger tight.  I then righted the frame
and engine carefully.  With the four bolts loose, I noticed quite a bit of space between the frame lugs and the engine
mounts.  I tightened the bolts on one side only, and then measured about 1/16 inch clearance between the frame lug
and engine mount on the other side.  I am referring to the rear upper and lower mounting points.  I have not bolted up the
forward triangular plates or lower studs yet.  It seems I can shift the engine in the frame 1/16 inch laterally depending on which side
I bolt up first.  I may also end up stressing the frame lugs that I tighten last.  While the lugs appear relatively straight, their width
is dictated by their welded location. 

So my question is....is this extra clearance normal?  The frame lugs do not appear to have been moved nor do the engine
mounts appear to be shaved.  What is the general practice for alignment of the engines once it is in the frame?  Any advice would be greatly appreciated. 
 
On my 74 there is a washer (shim) on the upper left rear between the frame and engine (I just looked)..I do remember using a shim there when I did my engine, don't remember if there is another on the mounting bolt below. I don't think so, but could be. The shim washer is about 1.5mm/2.5mm thick..by memory.

I had the engine out in 1976 and again in 2005..that shim washer was there from the factory. I think they used it for some clearance to help slide the engine into the frame when on the assembly line.
 
Thanks for your reply Rusty.  I dug out the old mounting hardware that I had fortunately tagged and bagged and tried to account for all the items.  I did find two extra washers that may have been acting as shims.  As I know the DPO had the engine out at least once, I cannot be sure what is factory fitted and what is not.  I am headed out today to purchase some shimming items and will center the engine as best I can.  I guess the true alignment will show itself when I set up the drive chain. 

Thanks again Rusty...


 
When fitting engines, I quite often find there is a lot of clearance at the lugs.  I then tighten the drive side and shim out the primary side to avoid stressing the frame lugs. 

Many bikes have factory-fitted shims, just as many don't...

piet
 
Piet, that is the way I remember it too...shim(s) were on the primary side and the drive chain side of the engine was a simple bolt up. That aligned the drive chain sprockets just fine. My 1975 3C did not have shims, as I recall. My 1974 does have them.
 
While on the topic of engine install, are there recommended torque settings for the engine mounting bolts, specifically the underside and the rear mounting bolts?    I can't find any such information in the various manuals and books.

Tom
 
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