learn from my personal disasters....

[AdminGuy]

In the photo shown. Ya, I'm going to tear down the top end..... again.....replace all the tappets.

The jims pinion shaft was a little tight for my NOS main pinion. So I rotated the wheels to the bottom and wedged the top of the wheels. Froze the shaft and heated the pinion till blue. Placed it on with glove over the key and placed a socket over the pinion and gave it a whack to seat it. It worked beautifully.

The problem seems to have come from the nut used to hold the pinion on. Is it the original? I don't know. Well, it's too tall. You can see where it dug into the cam cover. I'll have to file down the nut a bit -to get the cam cover to fit on properly. The pinion in this case may not be fully seated. But that nut shouldn't contact. What's with that?

I guess dry fitting and doing a couple of rotations to see if anything is contacting would be a good future insight. And check the fit of your main pinion before final assembly. Like -before you put the wheels together. Try it with and without the key. Shave the key if ness.

Anything else I should look for here?

[c.o.]

Thanks for the post Paul, that's something I'll have to pay attention to.

[inrustwetrust]

Your are going to hate to hear this, but smacking that pinion gear on is bad for the flywheel alignment. The pinion gear should be pulled on with a tool that is easy to make. Heating the gear to blue takes all of the heat treating out of the part. It is strange that the nut backed off the pinion gear, as it is left hand thread and is self tightening.

[AdminGuy]

Ya, I know it's bad. That's why I braced it. It didn't affect alignment. Checked it. runout.

If I pulled it on it wouldn't fit. The Jims pinion shaft was too big. I wasn't up to pulling the cases and wheels apart.

I think cherry red would kill the heat treat not blue. Well, if it fails I'll know why.

The nut didn't back off. it stands proud.

[Kojack]

It's hard to tell from the pic it that's the right nut, looks close though. Were the wheels centered in the cases? You need to measure the rods where they come through the baffles. They should be centered within 1/64". End play on the crank assembly should be .015-.020". Endplay is controlled by shimming the wheels, that nut should never be able to contact the cam cover. Could be that the taper on the Jim's shaft was too big which would cause the whole shaft to protrude too far. Rust is right about blue heat. Any color change at all can change the heat treatment. We used to bench harden small parts made from untreated drill rod. Heat till cherry red then quench. Clean off the oxide, then reheat till the part reached a light straw (tan) color, then allow to cool slowly. That second heating would take out some of the hardness but make the part a little tougher, also known as tempering. Blue heat might screw everything up but not always. Live and learn. Oh yeah, my 741 manual says that the gear is a driven on. I'd say a part that small shouldn't need to be more than .0001" or .0002" tight.

[AdminGuy]

Thanks for your help. Much appreciated.

Just got some more parts the other day. The cheap nut which I used is 0.223" tall. The expensive orig repoped one is 0.154" -Stark. Which would have cured this problem. Or you could grind/file the cheap nut down. The problem being that the cam cover will not fit/seal properly. I used modern 1104 sealent and didn't notice until removed.

So I figure my main pinion is seated properly. Rods centered. yes.

So just so guys are aware of this. And it's a scout not a chief. So may not apply.

Mike at Kiwi has some viton lip seals or something which replace the "hi-tech" felt seal on the shaft oil delivery to pump.

I really need some modern alt. lip seal for the main shaft exit to prim case.
Any direction? Ya, ya, I know- tit for tat. But easy to do when the cases are split. So why not.