View Full Version : Repro 45 cylinders - valve springs

06-05-2008, 12:37 PM
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?

06-05-2008, 04:21 PM
How long ago did you buy these cylinders? This is one of the issues we addressed when they had the first production run. They were changed after that, but......that was almost 4 years ago now.

You'll have to remove the guide and have the flange, raised part......whatever you want to call it......machined off. If I remember on the ones we did.....it was around .200"


06-05-2008, 04:31 PM
I just bought them recently on Ebay as part of a top end overhaul kit. I don't know who made them but the bag stated "made in India". I did not know until they arrived they were not OEM.

Is there a flaw in my using the 1932 - 1940 springs and shims? I am about to place an order from 45 Parts Depot.

06-06-2008, 08:17 AM
It is probably best to mill the new cylinders to match the boss height of the old ones. If you try using shorter springs it may be next to impossible to get the proper seated spring pressure.

06-06-2008, 09:28 AM
I agree with motorhead1, but you'll need to take the cylinders to a good machine shop anyway because there's more that needs done to make them ready to install.

They need to be honed to fit your pistons.

The valve seats need to be done correctly.....lapping them will not work good enough.

I can almost 100% guarantee the inlet nipples are loose. Every set I've done has to have the nipples removed....then I swap them to the other side....then tighten them correctly and then drill and reinstall the pin.

A good shop will check to see what your springs install height should be and check your springs for the correct measurements. They should be able to machine the raised part where the guide goes to the correct height and install everything.

You have to be very careful with these older sets because if they do have coil bind, you could end up splitting your cases.....and I don't mean the proper way.


45" Parts Depot

06-06-2008, 10:07 AM
Thanks to all of you for the advice and direction. Time to drop back and re-plan doing this. As I say, “There are no more 5 minutes jobs left, our forefathers used them all up!”. Thanks again.