I am putting a set of reproduction cylinders on my WLA bottom end, casting #120-36 with the 7/16 X 16 head bolt threads. The valve springs are coil binding and I have found 2 reasons why:
1) The cylinders have a 1/8” raised boss where the valve guides are pressed in, stock barrels are flat where the valve guides press in.
2) The repro upper push rod covers are twice as thick as the stock ones
Both add up to just enough that the valve springs will not compress enough for the amount of cam lift. Short of removing the valve guides and milling the boss off and replacing the guides, is there a “special” valve spring that is used with the reproduction cylinders due to that 1/8” boss?
The only garage alternative I can think of is to use the shorter valve springs from a 1932 – 1940. Palmer’s book shows the cam lift is the same from 1932 thru 1973 and the valves are the same also. The difference is the 1932 – 1940 used the double lip valve guide hence the shorter spring, shorter by 5/16” when the valve is closed. I was thinking of adding a 3/16” shim between the valve spring and the upper cover as is done on the later side valve big twins to get the correct spring length for the 1932 – 1940 valve spring when the valve is closed. Any other ideas for the garage mechanic?
1) The cylinders have a 1/8” raised boss where the valve guides are pressed in, stock barrels are flat where the valve guides press in.
2) The repro upper push rod covers are twice as thick as the stock ones
Both add up to just enough that the valve springs will not compress enough for the amount of cam lift. Short of removing the valve guides and milling the boss off and replacing the guides, is there a “special” valve spring that is used with the reproduction cylinders due to that 1/8” boss?
The only garage alternative I can think of is to use the shorter valve springs from a 1932 – 1940. Palmer’s book shows the cam lift is the same from 1932 thru 1973 and the valves are the same also. The difference is the 1932 – 1940 used the double lip valve guide hence the shorter spring, shorter by 5/16” when the valve is closed. I was thinking of adding a 3/16” shim between the valve spring and the upper cover as is done on the later side valve big twins to get the correct spring length for the 1932 – 1940 valve spring when the valve is closed. Any other ideas for the garage mechanic?
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