Oil Consumption

 

In 1932 the first V-8 Ford block was born. They had a 3 ring piston design. As the 30s went on Ford had oil consumption problems. They replaced millions of pistons and rings trying to fix the problem (covered under warranty).

 

By the late 1930s before WWII they went to a 4 ring piston design, adding another oil ring under the wrist pin. They kept the same design until 1953 which was the end of the Flathead. Never again to have a 4 ring piston design. This by the way, never solved the oil consumption problem.

 

The problem was in the valve guides not the rings. Valve guides serve two purposes. One, to hold the valve straight so it hits the valve seat exact. Two, to help transfer some of the heat through the stem into the guide or block in this case.

 

The valve in this case is called direct acting. It works directly off the lifter and the lifter works directly off the Cam. Unlike an overhead valve that has a mechanical advantage because of the rocker arm ratio. That means you can run a small diameter lifter and achieve the desired lift at the valve.

 

With a flathead you can only get lift based on the diameter of the lifter at the Cam. We call this the footprint. In the case of the flathead, the diameter, or footprint, is one inch.

 

Why am I telling you this? To machine a one inch hole at the lifter you have to be able to get a tool in there. That means we have to go through the valve guide area. So we make the guide holes bigger (1.030) so we can clear a 1 tool to machine the lifter bore. Now we have a guide that is 1.030.

 

We assemble it on the bench with valve and spring and the rubber O ring around the guide. Then we stick the whole assembly in the block and hold it in with a horseshoe clip. Here is our oil consumption problem. The clearance between the guide and the block has to be a few thousands, that allows the guide to rock back and forth until the bore 1.030 becomes not a straight bore but hour glass shaped.

 

That means the guide is rocking and not allowing the valve to hit the seat properly. Remember the only way to cool the valve is when the valve hits the seat and through the guide. Now the valve and guide is running hotter than it should. Also remember, we have a rubber O ring around the guide. Due to a hotter than normal guide our O rings have shriveled up now when the piston goes down it creates vacuum and sucks oil past the valve guide that is 1.030 diameter. Not just 11/32 (.343) like your everyday car.

 

Our new block fixes all of those problems. First we went to a mushroom tapped design. That means our tapped body is only 5/8 diameter and our footprint (part that rides on cam) is 1.200. So we have .200 more to give us much better cam designs. That means we only have a 5/8 hole for the valve guide but we are pressing in a modern 5/8 guide with bronze walls for the valve. This eliminates any valve movement so we have a good valve job, good heat transfer and significantly reduced oil consumption.

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