Is this a stupid way to hold my crank for building?

[Jameel]

I held my flywheel up to my engine yoke and two holes lines up perfect. So I ran up the hardware store and got a couple longer bolts, plus a couple spacers to mount it up. Feels solid. The flywheel isn't bottomed flat on the face of the yoke (it's maybe .5mm away) so there is a tiny bit of flex. I don't want to damage my flywheel though. Think this is a stupid way of doing it?

[fanaudical]

That crank is heavy. I'm not sure the flywheel was intended to have to support it when bolted in at the edge.

When I did mine, I threaded a few of the old crank-to-flywheel bolts in and the set the flywheel on a table. My approximate order of operations was:

- Install mains in case.
- Install crank in case do Plastigauge fit-up (before rods were on crank).
- Take crank out of case.
- Put crank on flywheel, but flywheel on table (crank goes vertical).
- Clamp flywheel to table to prevent toppling.
- Install rod bearings and rods.

Hope this helps.

[Jameel]

Thanks for the sequence. Sounds like you Plastigauge the mains, but not the rods? I've never heard of that before. It's the opposite in Wayne's book. Am I missing something?

I decided the spacers were not helping my setup. So I removed them and cinched the flywheel down so it's now resting flatly against the yoke. I also rotated the whole setup so the weight of the crank is into the yoke instead of away from it. It's solid as a rock.

[DRACO A5OG]

Oi, try placing it on the flywheel as a support. to install the rods for plastigauge work. Maybe on the cleaned floor for leverage.

[fanaudical]

Sorry - I omitted the plastigauge step on the rods. (I checked clearance on both the rods and the mains with plastigauge.)

It may feel solid, but I still recommend setting that crank vertical (flywheel horizontal on a table).

[scootergt3]

or at least support the pulley end somehow.

[2jmotorsports]

I believe there is a factory tool that holds the crank in the horizontal position but I do not have one. I had a junk engine adapter that came with my stand (probably for V8 engines?) and I drilled the crank/flywheel hole pattern into it to bolt the crank on.

As you can see I drilled one hole incorrectly. So far so good.






I did try to center the holes around the axis of the tube but the tube diameter lands right on the crank/flywheel bolt circle and didnt work. This is why they are offset on the adapter.

[nocarrier]

Why not make some V blocks out of some wood or something....

Personally, I would never hang my crank from one end like that without support.

Dump the plasti-gage and buy the tools or pay a machine shop a few bucks to measure and match the bearing to the bores to the journals.

[Tippy]

I wouldn't do it, and I'm not the overly cautious type sometimes.

That is a lot of moment weight on there once you start adding bits.

[Ken911]

i always just bolt the flywheel on and set it on the bench standing up. which is how cranks are supposed to be stored when not bolted into a block

[ajwans]

For reference, here's the factory tool for doing this job, goes into the P313 bench mount clamp just like the yoke can.



I made my own from some good angle steel and just clamp it in a regular bench vise.

andy

[Jameel]

Well, I've been paranoid about warping my flywheel after posting this. So I had my steel shop burn out a "bow tie" which I used as an adapter between the crank and the yoke. Works great. And now my flywheel is resting easy on a shelf.

I'm surprised no one makes something like this. Or maybe they do...

[Tippy]

I wouldn't worry about warping the FW as much as the crank

[Jameel]

Wait, what? Warping the crank? Factory has a tool specifically for holding the crank horizontal, Wayne mentions it in his book, countless builders do this. I'm pretty green here, so what am I missing?

[jpnovak]

I use a junk flywheel and clamp it in a vise. Makes it really easy to assemble and torque the rods. Go for it.

[Tippy]

Originally Posted by Jameel

Wait, what? Warping the crank? Factory has a tool specifically for holding the crank horizontal, Wayne mentions it in his book, countless builders do this. I'm pretty green here, so what am I missing?

I'd only it do it for the time it takes to install the rods.

I wouldn't store it that way. That's me.

The tolerance for the crank journals are measured in ten-thousandths. Bet you could put a dial indicator on the end of the crank opposite the flange and flex it slightly.

[KTL]

Stomski makes a very nice one that supports the crank at both ends, in either vertical or horizontal position.

https://www.stomskiracing.com/products/911-crankshaft-holder

[nocarrier]

I'm not going to say if it's right wrong ok or not. It's your crank you do what you want.

But from my experience with machine tools. Specifically with leveling a lathe and taking the twist out of a heavy cast iron lathe bed. You suddenly become aware how "plastic" cast iron and steel really is. It's a real eye opener.

With that being said. I guarantee you that crank is bending in your fixtures under its own weight.

[boosted79]

[911pcars]

You seem "bent" on mounting this in a cantilevered position. I worry that the jig you fabricated means the crank will sit that way for a period of time, allowing gravity to possibly have an effect on the straightness. As no carrier suggests, set it on a pair of v-blocks or equivalent or mount the flywheeel, then set it vertically on the workbench. A large lazy susan below it will allow full access to measure and inspect. FWIW, when work space was at a premium, I rebuilt an entire engine with it sitting on a lazy susan. However, your crank, but you asked.