Sunday, December 07, 2008

It's usually the simple things

My father was a fuel-systems R&D engineer for General Motors' Rochester Products division (now part of Delphi) for more than 35 years. Now retired, he worked on or led many product development projects, including Rochester's innovative "Quadrajet" four-barrel carburetor. Unlike most high-performance four-barrel carbs (e.g., Holley, Carter) the assymetrical Quadrajet had two barrels of smaller diameter, and two larger than those of a typical four-barrel. At low to moderate throttle positions it used just the two small barrels for fuel economy; punch the throttle and the two large barrels opened providing the combined air-flow of a typical four-barrel.

Dad also co-owns the patent for the first multi-orifice, flat-plate injector nozzle producing radially and axially offset fuel streams. Fuel passes through the injector body out of six incredibly small holes drilled at angles between 81 and 84 degrees from the vertical, creating six fine streams intersecting to atomize the fuel in the intake port.

The genius of the design was to maintain fuel velocity through the orifices, preventing injector clogging common to GM's other primary injector supplier. In the early 80's the competing injector supplier was costing GM millions in warranty repairs.

Dad was very much hands-on; his co-workers called him an engineer's engineer.
Out of the complex projects he worked on during his career he learned early-on that when problems cropped up it was usually something simple. A lot of time got wasted, he would admonish, looking at the most complex part of the problem first, when it was usually the simple things.

He gave this advice to me... often.

My second bike was a 1968 BSA 441 Shooting Star - the road version of the 441 Victor trials championship bike. In 1970 at age 19 it was a piece of work. It could be an entire cold-morning's assignment to start if you didn't have the choke, the feel for TDC, compression release, and the timing of that mighty downthrust perfected (you didn't "kick" start it. You hurled your whole body, stiff-legged onto that little floppy lever). Addictive, thumping torque at low revs and matching exhaust note were the reward.
But it leaked oil like hell.
(Photo courtesy of Scott Larson)

I remember a particularly unrewarding sequence of weekends spent fixing the primary leak - at the join of the cases. I rode the Shooting Star from campus to home, where dad had a great shop. I spent a three-day weekend disassembling, cleaning, polishing, fitting new gaskets and cement for a sure-fire cure to the damnable leak (in the end, it did). But on reassembly it wouldn't start. I tried a good many things and determined I had no spark. Nothing would restore it. I was convinced I must have managed to damage either the magneto or the primary coil. Dad was away on a test trip, and I was on my own.

Out of ideas and time, I borrowed mom's car to get back to campus and spent the next few days calling around for a new coil. I drove 50 miles the following weekend to get the coil, installed it, no spark. I drove the 100 miles to return the faulty coil and the dealer was good enough to test it and the old one - they were both fine. Return the new one, reinstall the old one and back to campus. Two weekends.

Dad is home from his Arizona Proving Grounds trip and I meet him on the third weekend. He spends a patient Saturday lunch listening to my successful repair of the oil leak, followed by the longer tale of frustration and deterioration into self-doubt over the electrical problem.

In the garage, he crouches next to me by the bike. Take off the points cover, he instructs. This takes 30 seconds. He pauses for just a moment and asks if I wrote down the order in which I removed the nuts and washers that hold the points to the inside of the case. Well, it seemed pretty straightforward so, no, I didn't. Pointing to a phenolic washer I have just removed, he suggests that I put it under the plate that holds the points, where it will keep the points from grounding out. Gosh. Not even five minutes and the Shooting Star is burbling happily in the garage.

This came to mind this fall when, on the last lap of the last day of the track season, my Ducati developed a horrible stutter and then mis-fire. So bad, I had to shut it off and coasted into my pit. It's that stutter a fuel-injected bike develops when its out of fuel and the injectors are firing dry (bad).

In the pits, plenty of fuel. Got spark. Maybe a broken timing belt. A broken timing belt might mean any number of expensive imported mechanical bits to cry over. But the timing belts are okay, the timing dead-on. Now what? I have visions of pulling the engine, finding, god only knows what.
It would have to wait for another weekend. We packed up and left.

Late fall had come and being lazy, I managed to summon the lesson of the simple things. And dad's fuel injectors. Maybe I really should be draining the race fuel out of the bike after every weekend at the track. Maybe the injectors are corroded. Maybe I'll have to buy damned-expensive new ones. Well, let's start with something simple.

Out comes the oxygenated fuel. In goes premium and injector cleaner. Every couple of days for the last month I turn the engine over with the plugs out to drive pump gas and injector cleaner through the fuel system.

Yesterday I put the plugs in and hit the starter. Not five minutes, and the Duc is booming away in the garage.

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