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Engine Restoration - Part 6

Updated: Jul 19, 2022

This section will cover the restoration of the valve train. After removing the ignition wires and exterior fuel and oil lines the original priming cups were removed and restored.


Priming cup prior to restoration.

Restored priming cups.

Cylinders before disassembly of valve train.


After removing the spark plugs and primer cups we were able to remove the port plugs using a special socket wrench found in the original Simplex toolkit. Each of the twelve port plugs was stamped with a number from the factory to assure proper reassembly.


Port plug after restoration.

Port plug after restoration.

John is modifying a conventional valve spring compressor to fit the valve spring cups.


After completing the modification to the valve spring compressor and fabricating a spacer to rest on the top of the valve head we were able to compress the valve springs and remove the split collet retainers. Next we were able to remove the valves, springs, and spring cups.

After removal, the valves were bead blasted and inspected. The cylinders were cleaned and bead blasted and we were also able to drive out the valve guides and inspect the valve seats. Upon careful inspection we concluded that eleven of the twelve valves had been replaced with new and had received very little use since their installation. One valve, the one nearest the firewall, had not been replaced. This valve was worn beyond use. Once again we were very lucky and found a NOS valve for its replacement. At this point all twelve valves were ground and polished in our lathe. The stem faces were also ground to provide proper contact and adjustment.


The valves are 2" inch by 9 1/4" inch with 3/8" stem diameter


The valve seats were then ground. The valve seat nearest the firewall was in poor condition. We assumed that the earlier valve repair work was done with the engine in the car and that the valve seat grinder could fit into the last valve port. Fortunately none of the valve seats needed replacement.

We also assumed that the valve guides had not been removed during the earlier repair work. Even when new valves with oversize stems are used, there are problems. A common mistake would be to purchase new valves with oversize stems and then ream the valve guides in place. Unfortunately with such long stems and excessive wear the valve guide reamer will follow the angular wear pattern of each guide. Of course, crooked valve guides and newly ground seats will not mate!


Valve guide with pin in place


The valve guides were driven out and placed in our lathe and bored to accept new replacement valve guide inserts. The reason for removing the guides and boring them in the lathe is to assure that the new bore is straight and concentric. The new guide inserts were pressed and pinned in place. The guides were then installed into the cylinder assemblies, they were then reamed to allow 0.005" clearance to the valve stems.


Valve guide after boring

Valve lifter

Valve lifter after disassembly


The valve lifters were removed, cleaned and bead blasted. The convex face of each lifter was polished. The face of each adjusting cap was refaced and polished. Next the valves were installed, springs compressed, and cups and keepers put back in place. The valve lifters were adjusted to allow a 0.018" clearance.


Valve guide retainer, A.K.A. "Spider"

One of the two valve chamber covers after restoration

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