Installing an engine - how to, and other problems

[duTch]

 

.... The new mounting bar I've been sent is 3/8" (part no. 67-1251) - is that the wrong diameter?.....

Looking at the through-bolt again after CL25 mentions it, I'm thinking mine is 7/16", and still need the spigot.

[morris]

When I lifted the engine in, I had the frame more or less in the state that yours is in with wheels and mudguards on.
The engine however had the dynamo, head, cylinder and pistons off. Also the gearbox innards had all been removed to make the unit as light as possible.
I still remember it was a hell of a job lifting it in without scratching the paint, partly because the right hand front engine plate must be loosely on, but does a great job of getting in the way wherever it can.
For the bottom engine mounts, I made a couple of stainless steel press fit bushes. They hold the front and rear tubes together so they won't wobble around while mounting the engine.
As duTch mentions, it's a 7/16 bolt

[bakerlonglegs]

Thanks again for all your advice. As the frame was bare I laid the engine on its side and lowered the frame over the top, worked well. That was a trial run. I stripped it back down for powder coat so next time will be ultra careful - lots of pipe insulation!

[AdrianJ]

Yep - I've just done this.
Scratched the frame a little, but it will touch up.
My back took a fortnight to recover and I didn't have the barrels and head on.
My frame is probably a bit strained but I found that the order I fixed the engine bolts mattered.
Under gearbox screws, then rear top bolt then front upper and finally front lower bolts and studs was the only sequence that worked for me.
The front lower engine bolt is a problem . Mine looked just like yours, but I needed a longer one to take a sidecar mount on the LHS, so I got some 7/16  EN8 bar and put a BSCY thread on each end. Still needed a bush to fit inside the frame lug at each side. I'm hoping that's done the trick. I need to make the sidecar fitting now - a ball with a hex on one side with a BSCY threaded hole.
Adrian.

[Bsalloyd]

There are two spacers required for the lower frame where the front and rear meet. I have never seen a part number for this item. The ones I have measure : 7/16"OD x 3/8"ID x 0.910" long. The holes are sometimes worn due to the studs being loose for long periods. You may want to measure the holes and make the OD fit your dimension. Lloyd L

[AdrianJ]

Thanks Lloyd, yes I had to make them.
Not being familiar with the plunger frame it took a while for me to realise they were needed.
I can't remember the exact dimensions, but I had to make them specially to fit. Completely missing on the original bike.
Adrian

[kiwipom]

hi guys, why is the install of this engine/gearbox so difficult? dose anyone know how B.S.A. factory did it must be an easier way i would have thought, cheers 

[AdrianJ]

I doubt that it is difficult with a brand new perfectly straight frame and all the appropriate bushes.
Adrian

[Swarfcut]

 For a typical semi unit plunger engine installation, it is far easier to build the engine into the frame. Make it as light as possible, start with the basic cases and gearbox. Leave the magneto, barrel, head  and primary drive off.  Assemble the gearbox to the crankcases, add the right hand front mount to the crankcase, tied on loosely  with a bit of wire or similar to stop it dropping off, do not bolt it on at this stage, as a bit of movement here  is needed.  Load this lump into the frame from the right hand side. The web in front of the camshaft is a nice carrying handle. Rotate the unit into its basic fore and aft position and lower the back end down to clear the upper gearbox mount. Move it backwards as far as possible to the frame tube, and there is usually just enough room to wiggle the unit sideways slightly to the left to allow the pesky right side front mount down past the frame lug as the engine front is  lowered. Then move it to the right and up to position the mounting plate. Once the engine is in place, this plate cannot be easily added, unlike the left hand one.
 
Without the primary drive, barrels etc the engine is light enough to handle without a hernia.  Padding the frame to prevent scrapes etc is a must.

  Try all fixings for ease of use before assembly. When the engine is in place, move as appropriate to fit all the bolts and through studs loosely, then tighten them all gently to minimise localised strain, before a final tighten.

 Swarfy.

[Black Sheep]

Didn't have that option without an unnecessary strip with the Star Twin. Had to get the complete engine and gearbox lump back into the frame after changing the gearbox sprocket. Don't try this at home...

[Rex]

+1 more for laying the engine unit (less head and clutch assembly in my case) on a piece of carpet and fitting the frame around it. Glad I did, because the top rear gearbox mounting was a sod to line up, and had I been jiggling the weight of the engine around it would have used up a whole months supply of swear words.
Eventually it was in, and with no damage to the frame coating either.

[Russ]

There should be a tube fitted in the frame where the front section joins the rear section. "Your 2nd photo". When installed your stud will be the correct diameter.
This "Tube" has been discussed before and from memory? I don't think it is listed in parts book.