Couple of clarifications from Chief engine rebuild manual...

[sirhrmechanic]

I have a copy of the Chief "military" manual. This is the 340B/344 manual. Great book!

First is on page 41-4. The text reads "Check the valve stems for wear. All stems should measure .370. If they are worn down beyond .375", replace them with new valves." Should this read "...worn down beyond .365..." It does not make sense. Figure it is a misprint? Any input?

Second is on 41-5. The wrist pin (little end bushing) shows a clearance of .003" on the wrist pin. This seems like a massive amount of clearance!!! When we set them on cars, we are going to .0005" clearance, with a tolerance of + .0002. So we allow .0005 - .0007. Of course, this is for pressure-fed wrist pins. But I could see opening up 'splash' wrist pins to .001 or .0015. But .003 seems like a recipe for a rod knock at the little end (double knock.)

Anyone with more experience than me in setting up these engines able to comment? I know British prewar car engines well... but a 1938 Chief motor is a totally new animal.

Cheers,

Sirhr

[harleytoprock]

I would set the valve stem clearence for .004. I would set wrist pin fit in con rod at .0005 to .001. Maybe they are trying to say .003 is the wear limit.

[cdf6333]

You're 100% right. .001" is max for wrist pin in the bushing, can be "tighter" in the piston as aluminum piston will expand. As for the valve, the guides are average .375" and the exhaust valve was about .371" and the intake .372", allowing for proper clearance, Clarence. (old machinist joke) Common machining practices are usually cool for Indians.
The valve stem wears about 1/2" below the keeper groove, and wear can usually be felt and seen easily. Replace the valves if you have any questions, the chrome stem valves available now are a lot better than the "good old days" products.
Bob, 54,000 miles on my 46 Chief. 2 bottom ends and 2 tops.

[sirhrmechanic]

Thanks guys... that's what I wanted to hear and confirms my instincts....

In some ways, engines are pretty much engines. But sometimes companies do things differently for a reason! I'll make a notation in the manual.

Any tips for splitting the flywheels? I'll be having them reassembled 'professionally' but want to dismantle and clean them myself.

Cheers,

Sirhr

[c.o.]

From the 4th Edition of J.B. Nicholson's book "Modern Motorcycle Mechanics".....

[sirhrmechanic]

Cory! Thanks for posting. That's great.

That said, I was hoping there was some 'less crude' methods. I would think that wedging runs the risk of distorting either the fiywheel or egging out the pin taper. That said, who am I to question a century of experience.... though I might make up few little screw-type lifter/splitting tools.

Illustration 253 is just scary. Chisels are not wrenches except in the most dire emergencies. And I would argue that replacing a crankpin is not a dire emergency, given how many tools you need to GET to the crankpin. As we say at the garage... not all butchers cut meat.

Cheers and thanks again!

Sirhr

[tfburke3]

Those tools arent crude in the skilled hand,(ok fig.2 is crude)but just a note before your attempt.You dont just split the wheels with the wedge.The wedge puts pressure on the taper,then a sharp tap to the end of the pin will make them pop apart.
Tom

[c.o.]

Errr.... I guess I should have supplied this as well... It would be interesting to see what you come up with for "screw-type lifter/splitting tools."