Engine work

Yesterday afternoon was a good day to begin the disassembly of the engine in the 41 for inspection and to fix the rear main seal leak.  I wanted to first make sure the valve adjustment had remained unchanged since the 235 had been run on the dyno last spring.  I had made one check strictly by feel sometime in mid-summer and hadn't made any adjustments.  The area under the valve cover was nice and clean.

In the above pic, I've already loosened the rocker shaft bolts.  Initially, I checked all the valve lash just to see if the push rods would turn with my fingers when the lifter was on the heel of the cam lobe.  All of them were perfect.  This pic reveals some of the head and valve train mods that were done last year.  The seals are visible inside the springs.  The guide bosses were machined for these PC type seals.  The valve springs and retainers are from Comp Cams.  Under each rocker stand is a .100" steel shim and each exhaust valve tip appears to be black.  That black is actually a lash cap that has been shortened to fit the valve tip.  The lash caps are about .080" thick.  These changes correct the rocker arm geometry due to the machining that was done on the head.  .100" was milled off the head and the intake valves were sunk .100" for valve to piston clearance.  Without the shims and lash caps, the exhaust rocker adjusters would loose contact with the push rod cups and the rocker arm would actually begin pushing on the spring retainer - NOT good! 
     Once I was satisfied that the valve train was in good shape, the oil pan, timing gear cover, lifters, camshaft and front engine plate were removed.  All these parts had to come off in order to replace the front plate with the one that is currently attached to the other block sitting in the 41.  That plate has had the front motor mount flange removed for better rack and pinion clearance.  Next was removal of the rear main cap and cleaning of the seal surface.  This old crank had some pitting and discoloration on the seal surface from the old "rope" seal that had been originally installed.

I used some 320 grit wet/dry sandpaper with some water as lubricant to remove as much of the old seal residue as possible.  It's not perfect but hopefully, the clean surface will provide a decent enough seal for the new neoprene seal being installed.  The "after" pic is a little out of focus due to the glare/reflection off the crank.

I measured the diameter of the seal area and found it to be 3.875".  I took the old seal halves and put them together inside of a hose clamp and checked the seal surface diameter.  It was 3.885" without deflected the seal lip.  That means the seal lip was .010" BIGGER than the crankshaft surface!  Kinda hard to seal anything that way!

 One of the members of the Chevytalk.org forums had previously posted a way to use the lip seal type seal on 235's produced before mid-year 1955.  The method involves removing a small amount of each half of the seal and using a .040" piece of tie wrap behind each seal half to create the proper seal diameter and seal contact on the crankshaft.  I'll post his directions along with pics of my attempt at this seal mod in my next blog installation.