Valve Cover Roundel

Gordon Osmundson Photographs'

A 2002 HEAD






During 2001 my trusty BMW 2002 began to not run right, loss of power, a bad tick at ideal. I had built this motor from a worn out factory rebuild back in 89 and it now had 170k on it. At that time, I had had the head ported and polished with oversized exhaust valves and the lower end balanced at both ends of the rods to within one gram by the legendary, at least in BMW circles, Dave Cruz. I now performed a compression test on it and found low compression on the #two cylinder. Time for major surgery.

I pulled the head and sure enough the #two exhaust valve was partly eaten away. The cylinder bores looked good, no scoring and only the faintest ridge at the top of the bore. It was definitely worth rebuilding. Time for a trip to the machine shop. Checking around, I found that Dave had been killed in a private plane crash, so I needed to find a new machinist. Import engineering, a one man shop on San Pablo in Albany was recommended to me.

Combustion Chambers #1 I went over and talked to Ken, the proprietor at Import Engineering and found that he could do all the things that Dave had done, he even had some of the same machine tools. I left the head with him to receive new exhaust valves and to have the intake valves re-ground. When I went back to pick it up, the entire head had been glass beaded (a process like sand blasting) and it shown like a giant multifaceted jewel.

I took the head home and was looking at it when a small photographic composition presented itself to me. Well, I had recently acquired a new macro lens for my view camera and here was something to do with it. In fact, it proved to be a lot of something to do with this new lens. When I wanted to add the valve cover, intake and exhaust manifolds to the photographic project, I went back to Ken and he became very interested in what I was doing and let me use his glass bead cabinet to clean-up these other parts. A couple of months and five 100 sheet boxes of Tri-X later, I was ready to put my car back together.

How many of us have seen an automotive head. They are actually quite common. If you own a car you own one of these. But have you ever seen it. Study its shapes and forms closely. Despite its at first seeming complexity, it is really quite simple, but also very sophisticated. And quite elegant in its own way.

This is an aluminum alloy head with an overhead camshaft and semi-hemispherical swirl cross flow combustion chambers. The cross flow design helps the engine to breath, while the swirl chamber better mixes the fuel air mixture which improves combustion and reduces emissions. The way it works is that a timing chain driven by a sprocket on the crank shaft, turns the cam shaft via the large sprocket chain wheel at the front of the head. The cam shaft cams actuate the rocker arms on the rocker shafts. The rocker arms depress the spring loaded valves. As the valves open and close the fuel air mixture is admitted from the intake side and the exhaust gases are allowed to escape from the exhaust side. As all this is going on water is pumped through the water galleries to remove waste heat and oil is pumped through the rocker shafts to the rocker bearings and through an oil pipe to the cam lobes.

Continued Below

Valve Cover Roundel Top View W/Manifolds Open Valve Cover Valve Cover Top View W/Manifolds & Valve Cover Half Valve Cover
Without Rocker Arms #2 Front Valve Stems Open Valve Cover Front Rocker Arms Without Rocker Arms #3
Studs #1 Front Intake Port Without Rocker Arms #1 Front Intake Port W/Spark Plug Studs #2
Intake Ports #1 & #2, #1 Intake Ports #2  Vertical Three Intake Ports & Combustion Chambers Intake Port #3, Vertical Intake Ports #1 & #2, #2
Intake Ports & Combustion Chambers #2 Combustion Chambers #4.jpg Intake Ports Combustion Chambers #2 Intake Ports & Combustion Chambers #1
#1 & #2 Comb Chambers & Cam Sprocket #1 Combustion Chamber Two Intake Ports & Combustion Chambers Combustion Chambers #2 & #3 #3 & #4 Combustion Chambers
Combustion Cambers & Head Bolts, #2 Exhaust Ports & Comb Chambers, #1 Combustion Chambers #1 Exhaust Ports & Comb Chambers, #2 Combustion Chambers, #3
Exhaust Ports Exhaust Manifold #1 Combustion Chambers #1 & #2, Intake & Water Manifold Exhaust Manifold #3 Exhaust Port
Water Manifold Down Intake Runners #3 & #4 Manifolds Combustion Chambers & Cam Sprocket Intake Runners #2 #3 & #4, #1 Water Manifold Up
Intake & Exhaust Manifolds with Combustion Chambers #1 Bottom View with Manifolds #2 Head Bolt Hole Bottom View with Manifolds #1 Intake & Exhaust Manifolds with Combustion Chambers #2

Going down the road at 60 miles an hour the engine is turning about 3000 rpm, the cam turns at half this speed or 25 times a second. The rocker arms, if you could see them, would be just a blur. The valve springs have to be strong enough to slam the valve shut in just a small fraction of that 1/25 of a second. In an hour each valve opens and closes 90,000 times. In the life of an engine, the valves open and close billions of times. When the exhaust valves are open, they are exposed to the heat of the exhaust gases and can glow red hot. Despite all this, automotive heads give years of dependable service.

Now look at the photos again. Form follows function. Every detail contributes to the overall function of the design. The architecture of the head is a certain way for certain reasons. There are far to many details and reasons for things being this way and that way for me to go into it all here. But as I study the design of this head, I can see its Teutonic origins and the passion of its engineers for automotive performance.

Edward Weston used to eat the vegetables that he photographed. He ate his photographs. I get to drive mine.



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