Engine Rebuild Part VII - Top End Assembly

Once the engine was in the frame it was time to start its final assembly. The cylinders were bored and honed by EV Engineering in Howard City Michigan and Ed did a great job.  Now it was on to fitting the rings. The end gap was checked in the cylinders and half were good while half required filing to make end gap meet workshop manual specs. Once calibrated to the bore the rings were fit to the pistons and the pistons were mounted to the connecting rods.

Measuring ring end gap.

Filing a ring to increase end gap. They were close but two needed slight adjustment. 

Pistons mounted, ready for ring compressors (so I thought) and cylinders.

Fitting the cylinders to the pistons is a straightforward procedure on my BSAs. I have a set of motorcycle ring compressors that work very well for this task. When I tried to use these on the Interceptor I found they did not compress small enough for the RE. No problem, they're not that far off so just make shims, right? Wrong. With the shims they would not fit between the cylinder bolts and I don't know how I would get them out if they did work. The bottom of the cylinders have a nice taper so I gave the old screw driver method a go and it worked well. I proceeded gingerly as I did not want to break a ring as this looks like it would be easy to do.  

My various methods to place the cylinders on the pistons without breaking the rings. Standard MC compressors, shims to make them fit the RE, a reversed zip tie, and my trusty screwdriver. Guess which one worked.....

The pushrod tunnels have aluminum rings around them which is not the way they left the factory. This is someone's attempt to eliminate oil leakage. It appears to have worked as the RE was relatively oil tight in this area and I left them in.  A rubber seal fits into a recess in the head and compresses them .04 in on these aluminum rings.  Non-hardening Aviation Permatex was used to seal things up. 

In this photo I am using an aluminum drift to re-install the "non-factory" sealing rings.

This is the first time I have encountered the Cross rings used in place of a head gasket. Cross rings are tapered rings that get pressed into a mating surface in the cylinder by the head. This setup replaces a conventional head gasket. I have read mixed reviews on them and was very careful torquing them down to keep things fitting properly. The torque value is rather low at 20 ft/lbs. I used two base gaskets to seal in oil and no compression plate which is an option used to lower the compression ratio. I have been using high-octane non-alcohol fuel which should make them unnecessary.

Cylinders mounted and Cross rings in place. 

Just add pushrods and bond to the sealing areas and it's ready for the head.

When I removed the heads there was no sealing compound found on the Cross rings although the manual directs its use. I reached out to my friends on the Yahoo Interceptor group and they recommended assembling the Cross rings with non-hardening Permatex, which I did.

Torquing the head to 20 ft/lb and making sure everything stays square by tightening in 25 in/lb  increments. 

The valves were adjusted using the new elephant foot adjusters. A good upgrade in my opinion although there is not much movement left for future valve adjustments. If I run out of room I will remove the heads and grind material off of the adjuster lock nuts. (I would have done so before installation if I thought this might be an issue)

The Interceptor's split cylinder design facilitates cooling but has the disadvantage of making a weaker engine assembly. Owners have devised methods to overcome the weakness which I have also included on my build. The head steady was strengthened with straps that tie the heads together. While not as strong as a one piece design it should improve the assembly and increase engine operating life.

The head reinforcement plates were made from 12 gauge steal and mount under the head steady. The head steady top mount hole's bottom end was lengthened to allow for the thickness of the plate while the top of the bracket cleared the frame as is.  

The top end installed and adjusted. Next it's on to cables and electrical.  

I'm currently reading Phil Irving's "Motorcycle Engineering". 
A great book for someone who enjoys learning the reason behind the design.