This is the third in a series of reports outlining my big bore engine project.  Part 1 covered the cylinder.  Part 2 covered the cylinder head.  If you haven’t read Parts 1 or 2 you can find them here.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1593567475

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1595224521/0

Part 3 covers the cylinder head cover.  I have incorporated several modifications to the head cover for improved oiling.  Since I will be running a high lift cam and the associated heavy valve springs, the cam bearings, cam lobes, and rocker arms will need all the help they can get.

Let’s get started.

To properly locate the oil holes in the cam lobes, I start by installing the cam chain sprocket on the stock camshaft.  Then lightly clamp the sprocket in a machinist’s vice and adjust/align the camshaft by rotating it and using the cross feeds until the #47 drill bit aligns perfectly with the existing oil hole in the stock camshaft.  Lock the worktable in place and fully tighten the machinist’s vice.  That will lock the setup in proper alignment for drilling the first cam lobe.

You end up with a nice chamfered hole.  Repeat the process for the other cam lobe.

And I grind a feed notch in the thrust face on the left-hand side of each rocker arm.  There are wave washers on the right side so there is ample room for splash oil to work between the thrust face and wave washer, but on the left side the thrust face is in contact with the opposing aluminum surface so there’s not much room for oil to work it’s way into the joint.  I figure the notch will help a bit.

The exhaust rocker shaft is locked in place by a bolt.  The rocker arm rotates on the shaft but the shaft can’t rotate in the aluminum head cover because of the bolt.  The wear is confined to the rocker shaft and the rocker arm.  Those components are relatively inexpensive as compared to the head cover, which comes as part of the cylinder head assembly.  Ya gotta buy the whole head to get a new head cover.

In contrast, the intake rocker shaft is free floating.  It is not locked to the head cover, so it turns in the head cover.  That rotation results in wear.  I figure the bores in the head cover in way of the intake rocker shaft should have as much lubrication as possible.  The high lift cam with the heavy valve springs will put a lot more load on the rocker shafts.

The right-side bore for the intake rocker shaft is well exposed to splash oil, but the left side bore is almost completely isolated.   To provide additional lubrication to the left side bore, I drill a small hole in the cavity adjacent to the left-hand cam bearing.  That allows pressurized oil to feed up to the rocker shaft bore in the head cover.

I run an oil pressure gage that reads pressure off the head cover.  I currently tap into the head cover at the right-rear head cover bolt hole.   It works well but there isn’t a lot of material in this area.  You can only cut about two threads.  For this Big Bore project, I decided to move the pressure tap to the transverse oil passage.

You can see here how thin the wall gets.  With tapered threads you run the risk of cracking the wall when you tighten the fitting.  I opted for drilling and tapping slightly oversize (Letter “W” drill) and then setting the fitting with epoxy.  The epoxy will form the oil tight seal.  I think it came out good.

This story wouldn’t be complete without discussing the wave-washers.  Those rascals can be a real pain in the keester.  You can get em started easy enough, but then the edge of the washer always seems to get hung up in the bore.  They’re pretty sharp too.  Seems to me if you got carried away you could put a real bad slice in your finger.   It’s tempting to just leave those little suckers out, but I bet she would be one helluva rattle trap without those wavy little devils.