Engine Rebuild Part VI - Timing and Primary

Mounting the engine went well although devising a method that wouldn't damage my nice paint job required some thought. The process took about 20 minutes after I had a plan. Once the engine was in place it was time to install its components. Most parts had already been cleaned up or replaced as necessary.  I elected to start with the timing side.

A bit rusty but overall in pretty good shape.

One of the things I like about antique motorcycles is that they are mostly mechanical. I enjoy learning about mechanical designs I have not run into before and the Interceptor has provided a number of them. For example it uses a unique layout for its timing side.  The camshafts are mounted high and rather far apart with an offset pin idler sprocket to adjust chain tension. Turning the pin adjusts the chain tension. A rather clever assembly. The camshafts can be removed without splitting the cases which enables relatively quick changes if needed.

After inspecting everything I placed my final parts order (I hope) to RE specialist Hitchocks Motorcycles in Jolly O'l England. Time to button up the engine! 

The camshaft lobes and bearings measured minimal wear but the idler sprocket bushing was well worn and replaced. The exhaust cam timing end oil seal journal was a bit corroded but polished up well in a lathe. The cam sprockets were pulled to inspect the bearings and to check for corrosion. Although there was a bit of discoloration no issues were found.

The cam sprockets were removed to inspect bearings. All looked good. 

The idler sprocket bushing was worn and a new one was ordered. 
A clever design using an offset pin for adjustment. 

Assembled , three sprocket timing marks aligned, and ready for the cover. 

The oil pump is also a rather clever setup although an odd affair for a BSA guy. I rather like it and hope it works well. I have read that it does. So how does it work? The crank drives a worm geared shaft that has an offset pin in its end. This in turn drives a plunger residing within a pump body which pumps in both directions. It seems like a lot of moving parts for what it does. I bought the Interceptor for many reasons and its unique character is one of them. This is a great example of that character. 

The oil pump parts set. Note the "home made" lower oil seal retainer which is documented in a previous post:

http://keepingtherockersrolling.blogspot.com/2017/02/timing-cover-oil-seal-retainer.html 

The oil pump plunger and body. An interesting design. 

The timing side with its cover....waiting for points and condensers. 

Although the timing side appeared like it had not been apart, it was obvious the primary had been worked on over the Interceptor's life. The clutch plates had been replaced, one of the clutch bolts was new and the chain tensioner adjusting pad had been lengthened to possibly accommodate a stretched chain.

The Primary side "as found".

The RE clutch has a drum with bonded sections in its bottom. The plates had been renewed at some point but these sections were not and were soft. I scraped the old ones out and bonded new ones in place with an epoxy called JB Weld. This stuff is touted to work miracles if you read the package and is actually quite good. The bonded plates all measured close to new and the steel plates were flat. I renewed the springs while I had it apart. The chain appeared stretched and the nylon pad on the tensioner was deeply grooved.

While assembling the clutch basked a bolt broke off quite easily. My lovely redheaded assistant purchased me a set of left hand spade drills many years ago which made quick work of removing the broken bolt. One of these bolts was new and probably replaced one broken by a previous mechanic.  All three were  renewed before final assembly. A good note to take for future rebuilds.

Parts inspected, cleaned and new sections bonded into the clutch basket. 

Time for a new wear pad. 

Chiseling off the old rivets and installing a new wear surface on the tensioner shoe. 

Final drive assembled and the primary housing in place. 

Building up the clutch ....don't forget the retaining clip!
Although it is mentioned in the workshop manual I did not see it in the parts book. 
(Since posting this I have learned not all SII's have this clip)

Primary components installed and ready for adjustment. Check out Don Morely's "Greabox Rebuild PT5 Clutch"  for tips on setting it up.

A recent read and a very good one. 
If you own an Interceptor you would enjoy Andrew Strait's "The Mighty Interceptor"  

Also.....The Hornet recently took 3rd in the Masters Class at the 35th Annual Battle of the Brits in Milford Michigan. It was another great show put on by the Metro Triumph Riders. Check the pics out on my Facebook page:

https://www.facebook.com/pg/Britishmotorcyclerestorations/photos/?tab=album&album_id=327478124381207