Friday, 12 August 2011

End of the strip down - its all build up from here.

Having managed to arrive at a bare engine block, I finished the strip down by removing the gudgeon (wrist) pins from the original pistons in order to recover the original connecting rods. The pins are a press fit, but fortunately I have access to a 50 tonne press at work which made light work of the job requiring a measly 5 tonne to push them out. The next job was to get the parts over to the machinist, so with a borrowed van, I hauled the block, crank shaft and con rods from the original engine along with new pistons, piston rings, bearings (main and connecting rod), flywheel, clutch, damper and timing set to Rob Walker Engineering near Oxford. This company comes highly recommended from a few guys in the office, so I knew it would be worth the effort. The machining list was quite comprehensive:
  • Deck the block to zero clearance (increases the compression ratio to improve power output)
  • Bore out and hone the cylinders to the new (oversize) pistons
  • Grind the crank journals to the next under size diameter
  • Weight match the pistons
  • Weight match the connecting rods
  • Dynamically balance the rotating assembly
  • Install the con-rods onto the new pistons
Two weeks later I was on my way back to collect everything and the quality of the machining work was excellent - the recommendations were well placed. Since it was a bare (and now substantially oil-free) iron block, I proceeded to de-grease the outer raw surfaces then treat them with ‘Metal Ready’ as used on the suspension parts. This serves to both neutralise any remaining rust and provide a Zinc Phosphate coat to which the top coat can adhere well. The last stage was to apply the Ford Blue engine enamel - this is not an original colour for this engine nor the installation in the Cobra, but I liked it!

From here, I need to continue to collect together the parts to rebuild the engine. Matching the camshaft, rocker ratio and cylinder heads will be key to get the most out of the package and I believe I am homing in on a combination that should work well together. Only time (and the dyno) will tell!

Tuesday, 9 August 2011

Bearing Up (or out)

Despite the lack of Cobra updates, I have not been totally idle. Since my last update, I have been slowly completing the engine disassembly, to the point where all that remained were the cam bearings. These need to be removed for the machining work, the fact that they are worn out is incidental at this stage! A cam bearing is typically removed or installed using an expanding mandrel to hammer it in or out. I have heard some stories of bearings being damaged by this process, so I decided to design a tool to wind them out and in on a thread. I then turned the required parts (5 different bearing sizes so 5 individual mandrels!) and gave them a test. Success! The 5 bearings came out without a hitch.

The other area of progress has been on the gauges. I have never been keen of the normal kit car approach of a set of aftermarket warning lamps festooning the dash, so I thought I would take a more contemporary approach. To this end I have decided to attempt to manufacture my own gauges so I can integrate the lamps within the dial faces. This has taken quite a lot of research, but I am now at the stage where I have a schematic and board layout for the minor gauges (fuel level, water temperature), along with a plan for the major gauges (speedo, tacho). Oil monitoring (pressure and possibly temperature) will be achieved with the use of an LCD which will also provide trip and mileage information. There is still a long way to go on these, but it seems to be in the right direction so far.