Greetings . . .

I got my hands on an apparent NOS crank for an early '50s powerglide car:




I plan to use it to stroke my 216 - one of many tricks planned.

During my inspection of the item all looked well except for some rather tough looking grinds on two of the counter weights:


both inlcude strange markings below the grinds:


Are these grinds part of the normal balancing work done at the factory? Or has this part since been ef'd with?

I am going to send it to a machine shop for balancing. Should I have them lighten it as well?

Any insights will be greatly appreciated.

regards,
stock49

That doesn't look to stock anymore to me. It looks as if someone was trying to knife edge the weights.???????

Yeah that's what I thought - but wasn't sure since I have never worked on an engine this old before.

The only the grinds that looked kosher to me were the straight cuts (with inspector marks):


which is what I've seen done on the 60's era v-thingies I have wrenched on in the past.

I guess I'll just hand it over to the machine shop to get it balanced. Should I ask them to take out any more weight?

I am following the guidelines laid out by Roger Huntington, Floyd Clymer and Bill Fisher in terms of 'souping'. Roger suggests in his book that the crank can be lightened by as much as 5 pounds - but says: "This is not widely practiced ahd we won't recommend it one way or the other, since the performance improvement would be very slight at best."

What do you think?

stock49,
i've seen those "Z" ( could it be the mark of zorro!!) looking marks before. probably factory but i don't know what it means. i'd just have the crank balanced. the flywheel is what is usually lightened & that won't give you any more HP just makes it wind faster.

robert

This might seem elementary but don't forget to take your rods, pistons, and rings to the machine shop so they can balance your crank to match those.

I seem to recall pulling a '57 235 apart a few years ago that had similarly wierd grinding on a couple of the counterweights. I vote for "its factory"...

going on a diet, it involves the question what do you want- high end HP or low end torque?
Since the head doesn't breath all that great, I'd vote for low end torque and just get everything balanced. If you read through that Huntington book, I believe he basically says the aluminum flywheel and lighter crank are for higher rpm racing usage. A big heavy '49 Chevy needs torque...

Hey Deuce . . .

Not sure that I follow you. Those reciprocating masses can all be weighed for equality. And, I have never heard of crank bench that would spin anything but the crank and perhaps the flywheel.

How would the shop use these parts in establishing a static balance for the crank? In turn, if all these parts weigh the same then wouldn't the balance be un-affected when they're installed.

Am I missing something here?

Isn't it just v-thingies where crank counter weights need to match the reciprocating masses they are to offset?

regards,
Keith

Thanks Gearhead . . . the work seemed aweful crude for factory - but there's alot on the car that isn't very sophisticated. For me that is why its so interesting to work on cars of this vintage . . . one doesn't need a degree in mechanical engineering . . .

I am favoring tourque over RPM as this will be cruiser not a drag car. Interesting that you characterize a '49 Fleetline as heavy. At just a scoche over 3100 pounds it is relatively light compared to modern cars packed full of options.

regards,
Keith

It's all in the power to weight ratio...