Thanks for the input guys, and having a camshaft made is not out of the realm of possibilities for sure. Before I did something
like that I would first want to know that everything else was in good shape, straight and true .......I had a couple of custom cams
made for some experimental aircraft engines and the cost was surprisingly reasonable.
But, I have good news!
I decided I would pull the camshaft and try and correct the issue previously discovered (cam lobe not centered on IP tappet
roller). So yesterday I pulled the camshaft, and after some measurements I decided I would shim the camshaft 0.010 towards
the IP side of the block. I knocked out the pin on the camshaft collar, removed some material from the collar and then added
.010" shim to the inside of the engine/camshaft which line up the fuel pump tappet roller perfectly with the corresponding lobe!
I put a grade 8 bolt and lock nut back where the taper pin came out of the camshaft collar, so a camshaft should be a breeze
in the future. Some red locktite on the nut will assure it stays in place.
It did of course move the lobe under the intake lifter tappet as well .......good! So I checked for gear-train interference and found
that all looked good. I decided to get on the lathe and make two tools that fit the tappet guides that had a pin that would go
down and touch the corresponding camshaft lobes, the purpose was so that I could make some measurements and what I found
was that the intake guide was NOT vertical, it was a couple degress off from the vertical plane ........the shoulder of the tappet guide
was true and the bore was where it should be ........but the lifter is actually sitting sideways! I pulled the exhaust guide and put
a steel ruler across the block ......and in short I found a casting flaw with the block right where the tappet guides seat. The exhaust
side was straight and flat but the area around where the intake guides sits was not flat ......there was actually a low spot about halfway
around the hole in the block where the guide sits, back near the cylinder, with the guide in place you really did not see it. So the
intake tappet guide actually sat at a slight angle ........not flat like it should have.
So I could either make a custom guide that would correct the problem or fill the low area of the block.
I decided to remove all the paint and get down to good metal and lay down some filler, I used JB Weld and after heating the area
with an industrial heat gun so the JB Weld would thin out and flow evenly I filled the low area and let it cure overnight. Today I sanded it
and test fit the intake guide, it fit like it should, I re-inserted both guides then my two lifter pin tools and verified that the guides were now indeed
parallel with one another, I polished the tappets faces and I painted things and put every thing back together! You cannot tell this work was done!
I'm sure if I bead blasted the crankcase I would find lots of body filler .......but the JB Weld will be there forever!!
When I turned the engine over by hand the intake lifter now rotates about 75 degrees every time the tappet lifts ....YES! I exhaust side
spins a little faster but it does that on my other engines as well.
While I had the camshaft out I compared it to a NEW spare camshaft and there is no wear, I would have thought that with the tappet
face riding the cam lobe at an angle it would have worn the lobe face that way too .......but it did not! The lifter face barely had a mark
on it after 600+ hours (652 hours to be exact). I guess the low spring pressures, 800 rpms ...plus clean oil prevented that!
So anyway I ran it this afternoon for 2 hours with 4kw on it (I have a small suitcase load-bank) and I made several transitions to
5kw and it ran perfectly ....and both tappets spinning like all-get-out! I am satisfied.
So, I'm NOT sure if the camshaft adjustment made the tappet rotate or fixing the block so the tappet guide sat flat made it rotate. If I
had to guess it was fixing the block so the tappet sat correctly and allowed the tappet face to meet the cam lobe squarely. The camshaft
needed to be corrected ......so the IP tappet roller or cam lobe did not wear abnormally, so I'm giving credit to both!
Xyzer you sort of pointed at that very thing in your post ......thank you for the guidance.
I have had great service from this engine for 650 hours, I'll be happy to get that many more!
Thanks for everyone's input and comments!