Friday, November 30, 2012

"What's in store for Elizabeth," continued...

Hi guys,

I'm still feeling under the weather with my sinus infection...but on the bright side I have plenty of good medication to help me get rid of this crud. Hope to get healthy quickly, because we're having some warm weather this weekend and I'd love to go for a ride.

A sight that I'll soon be seeing again- my engine in bits
on the floor of Wedco Machine Shop in Jackson, Wyoming

 Anyway, in my last post I talked about diagnosing the problem with Elizabeth, which was determined to be extreme heat and lack of lubrication to the top end due to a sketchy oil delivery system. Now the question remains; what could be done to improve on this design flaw? While there are several possibilities for the rebuild, I feel that it depends on the intended use. Am I building a high-tech, redesigned race motor that can withstand great endurances, or am I building a reliable, every day machine? For the sake of conversation, let's say that I went with the former; what would a motor like this entail?

My dear friend Mike Wild and his heavily modified
Rudge Four Valve that he named 'The Bastard'
Now that everyone has had a bit of time to sit back and unwind from the race, there has been a small bit of talk on how the machines could have been improved- hindsight is 20-20, after all. I've recently been in touch with my speed demon friend and riding partner, Mike Wild, about how my motor could have been improved. Mike's own bike, a "1925-ish" Rudge combined a 1928 overhead valve engine and gearbox with 1925 frame and front end, and was heavily modified for the event. Mike modified his lubrication system to a direct feed oiler; instead of the crank and big end relying on "splash oiling", the big end is fed a constant supply of oil. Both he and I feel that this would have been a very important feature to have on my motor (considering that my crank seized the day before Yellowstone National Park due to lack of oiling). A direct feed oil set up wouldn't be that difficult to do, and would provide a much larger comfort shield around the big end. When my crank seized, I was able to buy a spare from my pal Jim Crain; designed by Atlas, the new crank pin operates smoothly and uses a sealed bearing cage. It required very little modification to fit in the crankcases (light sanding on the studs).

Fred Ham on his 1937 Harley EL. In a 24 hour period, Ham
rode 1,800 miles on this machine around a 5 mile track at
 Murdoc Lake. This Harley was mostly stock, with the
exception of polished engine internals and air filter snorkel

The next design improvement actually comes from my friends Dale and Matt Walksler at the Wheels Through Time Museum in Maggie Valley, North Carolina. In 2007, Dale built a 1937 Harley Davidson EL Knucklehead as a replica of Fred Ham's record breaking machine. For those not familiar with Fred Ham, on April 8, 1937 he took his 61 cubic inch Harley Knucklehead and set a new riding record: 1,800 miles in 24 hours around a 5 mile track in Murdoc Lake. This record stood for 70 years before Dale hooked Wayne Stanfield into riding an exact replica to beat the record. Well, they almost beat it... The thing that stood out to me was that in building the motor, Dale had the crankcase interiors and outer circumference of the flywheels polished to a high sheen. By polishing these internals friction would be reduced, thereby allowing the oil to flow smoothly throughout.

With these ideas swirling around in my head, I contacted my fellow BSA-er Jim Crain to get his two cents on what could be improved upon in the motor. One thing that we both agree on is that there is some valuable space in the combustion chamber that is being wasted; our flathead engines contain a hemispherical combustion chamber---yes boys, it's a hemi. Both of us used newly manufactured pistons from JP in Australia, but like the original, they have a flat top instead of a crowned shape. If you'll recall the new piston was also a bit heavier than the original NOS piece that was removed from my engine. So with all that being said, we both feel that having a piston designed and manufactured in line with the original dimensions and weight would be effective. These new pistons would be designed with more of a crown shape to take advantage of that hemispherical combustion chamber and would include narrower ring groves and provisions for a larger gudgeon pin. I also wonder if some modifications to the length of the piston skirt would be of good use.

In addition to modifying the piston design, another point that Jim brought up was that the connecting rod could be improved as well. Rather than using the steel connecting rods in the motor, Jim proposed that a replacement aluminum or titanium rod would reduce the weight and vibration. For the most part these modifications wouldn't be too costly, however the variances, tolerances, and measurements would need to be pretty much dead on, lest we face higher costs in R&D.
Titanium connecting rods and re-designed pistons....
both of these would probably shed considerable
weight from the inside of the motor.
Just as an overview, if the idea was to build this same motor for the same trip, I would build mine with a redesigned piston, titanium crank, Atlas crank pin, direct feed oil, and highly polished crankcases and flywheels. Okay, so what about for a classic that won't be subjected to such torture? Since I'm not going to push this bike across America again I'll probably rebuild it in this fashion, so I can't say whether or not I will go through with a newly designed piston and con rod. One thing is for certain; I will have a new piston manufactured to the weight of the original, and highly polish the internal cases. Who knows, I may even convert the big end to direct feed oil.

The Texan and his trusty steed
I intend to get Elizabeth back up in running order over the next month, though it will probably feel much different to have a proper workshop and workspace to rebuild it, rather than a parking lot. Recently I received new bronze bushings from the McCaster-Carr Company that will be machined to form the new small end bush. Once I receive a new piston and set of rings, it's down to pressing in the small end bush, balancing the crank, building the lower end, adding the piston/rings, putting on the cylinder, timing it, and viola! Not too much, right?  We will be back on the road shortly...look out everyone, Elizabeth's graceful self will be touring the countryside again soon!


Buck Carson
Carson Classic Motors Race Team


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