Sunday, April 2, 2017

Engine Rebuild - Part II - Crankcase Teardown

The Series II Interceptor crankcase was a new design for '69 and had features that differed significantly from its predecessor. The engine was now a wet sump design with varying oil pressure between the head and crankcase. The points moved to the forward section of the timing cover and the oil pump moved aft. These changes gave the engine a new look making it easy to differentiate from its predecessor and other makes.
A new design for '69. A real beauty. 

The Interceptor's engine and transmission layout also stood out from others. Triumph and BSA used a unit construction design and Norton carried on with its separate engine and transmission layout. The Interceptor used a semi-unit design which tasked the engine to be a section of the frame.
Cooling fins on the lower cases are part of  the Series II wet sump engine design. 

Royal Enfield advertising touted the craftsmanship and performance of the Interceptor that set it apart from other makes. Several of these features were found in the crankcase; a dynamically balanced crankshaft, camshafts that could be swapped without splitting the cases, and wired connecting rod bolts clamping numbered rods and caps together. An optional oil cooler was designed to reduce engine temperature under heavy use. A great idea for an air cooled twin. The Interceptor was a premium motorcycle.

Semi-unit gearbox and engine design. The Albion transmission is bolted directly to the the engine. 

The oil filter and cooler. A well constructed unit. 

The chain driven dual cam setup remained along with the plunger oil pump although they were moved to new locations. To the dismay of mechanics a timing cover oil seal retainer was not included setting up the engine for a potential oil pressure loss. This is frequently discussed by Series II owners and several methods to add a retainer have been developed. I took the advice of my peers and fixed this weakness on my Interceptor. The upgrade was detailed in a previous post.
A mechanical marvel with a mile long chain.  

Readily removable camshafts for the race tuner. 

The plunger oil pump....very unlike my A65 BSA's. 

The engine tear down offered no surprises except for an aluminum chip which was found in the oil sump. It appears to be casting flash. The cases were difficult to separate which was caused by rusty location dowels holding them together. I worked gingerly with a wood clamp, a screwdriver, popsicle sticks, and a pine block. PB blaster, my old friend, loosened gaskets and dowels up a bit. Great care was taken not to mar the castings. After the cases were separated it was on to inspecting the internal bits. Although in need of rebuilding, no significant problems were found.  
Using a reversed wood clamp and several other tools to open the cases. 

Getting there.....soaking in solvent for a bit. 

Inside the cases...things look pretty good. 

Rusty dowels made splitting the cases difficult. 

The neat bits inside....wired connecting rod bolts speak performance to me. 

Numbered rods and caps show an attention to detail.

The manual calls for 1/16 inch spacing on the timing side bearing measured is pretty close. 

Time to clean, inspect, and rebuild the crankshaft. 

A follow up to my last post. Another photo taken while "Grandpa Ken" was on an extended trip across the pond in the early 40's.


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