Flathead blocks

Ken/Alabama

Ken/Alabama

Well-known member
O.K. here it goes. I have been around flatheads now for better than 20 yrs. Just to be clear on this ,is the crank or the cam offset in the block ? I always thought it was the crank that was offset but my machinest says that the cam is and not the crank. Im sure this has been covered here before . I do know the valves are different from one side of the block to the other.
 
I believe the crank is offset relative to the cylinders. I guess the cam may be also, as the valve angles are not the same from side to side. The valve angle disparity can be seen without any measuring.
 
Ken, the crank is offset. It was old Henry's idea to compensate for a harmonic balance to the engine. Did I say that right?
 
There is no reason for your machinist to think the crank is offset. Both head decks are at the same height, all the pistons have the same compression height, all the connecting rods have the same C to C length, all the crank pins have the same stroke, all the valves and tappets are the same length.

The camshaft is offset from the crankshaft in slightly varying values from year to year.
 
The crankshaft was offset per the DeSaxe principle that was engineered in to give a slight advantage of leverage for the designed direction of rotation of the engine.

Kerby
 
Rotorwrench is correct. Mostly. It also has an effect on the duration of the piston at or near TDC. If you think about it long enough your head will explode. Wayno
 
rotorwrench said:
The crankshaft was offset per the DeSaxe principle that was engineered in to give a slight advantage of leverage for the designed direction of rotation of the engine
Kerby
Click to expand...

Were they all like that starting in 32 or was it one of those things that came along later as the V-8 evolved.
 
After some more head scratching (and measuring) I figured out that the crank is NOT offset but the cylinders and the cam are. Then I reread this thread and the one Jim Marlett referenced and it all added up. The De Saxe principle comes into play because of the offset cylinders. I'm slow but tenacious. Thanx everyone for getting my brains straight on this one. Wayno
 
The attached illustration from the July,1932 Service Bulletin may help to visualize the offset.
 

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  • V-8 camshaft-crankshaft orientation-2.jpg
    V-8 camshaft-crankshaft orientation-2.jpg
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That picture tells a great story. Sorry Wayno, it looks like it's the other way round. Cam is on center, Crank is offset to the right. Cylinders are on center. So if all the rod lengths are the same, as are the pistons, then the deck height must be a little higher on the right side of the engine. The crank is offset towards the thrust side, to reduce the thrust friction. It all makes sense now, the actual offset is 3/16", relative to each cylinder, resulting in a smaller (.265") horizontal offset of the crank.

God, those guys were clever!

I knew I had seen that diagram before, thanks for posting it.

Mart.
 
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