If you read leo Santucci's book on the Chevy 6 and you investigate cranks he alludes to the fact that the early 64-65 crank could be a real power adder becasue it has less mass than the later 250-292 cranks and their counterweights.

Do I understand that right? I mean if eliminating weight is the key to making thes eengines rev faster why are more people doing this? Is there a problem sourcing these cranks (i have one) or simply a chore to get them to balance out smooth and not produce vibration.

Come on engine builders are these cranks a Top Secret speed device?


James Kuenzi

Fredsgarage
San Leandro, Ca.

1965 Chevy II Coupe
250 Hot Six
converting to Muncie M-20 by years end.

Less counter weights = more vibrations = less power = shortly lived engine.

Seriously,the more counterweights the better it can balance out and smooth vibrations.


MBHD

MBHD,
Would running the lighter crank with a SBC balancer like those sold by LARROWE AND SONS give you less vibration with less rotating mass, or would the heavier balancer cancel out any advantage?

Z

I want a smooth engine too, but there are some serious racers paying big money for lighter cranks. AND if Leo is suggesting that there are some big possibilities here then SOMEONE out there must have tried this? Anyone? care to chime in?

I'm just curious as I have one of these cranks and wondering if I should attempt this on my next engine build.

James

Yes they can be used BUT??????? who wants to lose cubic inchs. when You can just make the stock crank lighter.Especialy in a 292 That is a Big cubic inch Loss.If you used the 194 crank in it.

Freds Garage,,,,

What crank do you have?
A 292 forged? 194?

MBHD

Just for giggles ..

I have a '64 292 forged crank that has no home to goto...

Main thing is to keep your counter weights stock,really no need to lighten it.
Maybe knife edge it & deburr.

What damper are you referring to from LARROWE AND SONS ?

Generally speaking a heavier damper cancels out bad vibes.

MBHD

Fred, most of my experience is from circle track racing but through experimentation just a light deburr & streamline is the best approach; the counterweights are close to the crank centerline and it takes a heck of a lot of work in that area to see much gain. The flywheel having a much larger radius from crank centerline will gain more with less work; I use an automatic flex plate with a mini-clutch and a 6&3/4 or 8" dampner (230 or 250/292).I have literally spent hours on counterweights and find that controlling other chassis related variables gives more acceleration than spending hours polishing counterweights;the cranks seem to last longer also.Since the cranks are balanced without bob-weights any reduction in rod,pin and piston weight gives a gain in durability.Remember that other opinions may vary but generally that system worked best for me ...good luck

MBHD,
On the Larrowe website, under "Misc. engine parts" they sell a 6 3/4 and 8 inch Powerforce damper. They are for SBC from Professional Products and and according to the PP website they weigh 9.3 and 12.2 pounds. Larrowe says they fit the 194 crank snout but "In all cases the crankshaft must be drilled and tapped to 7/16" and an SBC vibration dampener bolt kit must be used."

Z

MBHD,

I have the 194 crank. And yes Twisted6 mentions I would lose cubic inches, so that is now out the door. I have some .60 over pistons for my next 250 project engine where I will attempt combining a turbo Charger. Just trying to get my inlines eggs in the same basket.


James

aka

Fred's Garage

You could use either one.
Also,you do need to drill & tap the crankshaft for a damper bolt.

MBHD

I see in your sig,you plan on installing a 4 speed tranny?
W/a turbo I highly advise running a automatic.
Two cents thrown .:-)

MBHD

Given all being the same within an engine, EXCEPT the crank. A shorter crank will give more horsepower per cubic inch but not more overall. Like they say "there's no replacement for displacement". Bigger is better! Harmonics in a crankshaft are mean, nasty, evil, wicked, awful and ugly. Do all you can to dampen them.

Within reason there is no power or certainly no measureable power or useable power availble from reducung crank wieght so the engine can rev faster.
I doublt you could measure it . The mass of the vehicle exceeds by far any influence removing weight of the crank will. Notice I did say with in reason.
Crank needs to be strong. It is not the big problem weight wise that many hope it will be. I know a hundred will tell me I am wrong and that Bucky Wooppedeedo in Pensiltuckey Iowa put in a lighter crank and went four seconds faster but it just aint so. It is not that easy. Best place to reduce weight is con rod and pistons. That reduces load which is always nice provided strength is not reduced. Certainly one would not want a 500 CAT diesel crank in a 250 chev 6 but we are talking about a relatiely insignificant difference here.
But you know if it makes you feel better go for it. Beter yet run yer car with the 250 crank then change NOTHING but the crank (I mean it, no new spark plus and wires and fresh carb etc etc.) just change the crank and see what difference you get. That is how we test stuff.Sometimes we dont like the results but that is life. I would be surprised if there is any measurable difference but ol Smokey said "one test is worth a thousand expert opinions."

i think Bucky moved to Iowa from Ameliasburgh Ont. it's too warm here though and he misses his friends. tom

could be ;>). Or maybe not. A little internet research will tell you.
D

That was not meant by the way to in any way slight your lovely state which I have visited and enjoyed.
It is merely an old expression

I culled from this conversation that the lighter 194 crank that I own may not be all I hoped it would. I will listen to the voice(s) of experience here and offer it to the first taker who has the shipping fees to experiment with. I give up.

I need to concentrate on working the bugs out of what I have already created.

And I am still going to put the Muncie in later this year. I hate slushboxes.

James

Im running a 250 with the 407N factory lighter crank with a 6 3/4 sbc damper (summit brand) and it revs real great now. No real vibrations at all up to the rev limiter at 6400. And it gets there alot faster than it used to with the stock balancer. Plus another added bonus is the flywheel stopped comming loose. I also have a 153 tooth flywheel from a vette that weights 15 pounds and a muncie in the car. The whole lighter rotating assembly seemed to do wonders for the reving of the engine.

I think the main reason your engine revs quicker is because you finally have a good damper installed.
I know that is why a few of my 250's reved quicker is because I installed a better than stock damper.
I weighed my ligher weight 250 crank (407N) on a bathroom scale it weighed 3-4 lbs lighter than my standard 250 cranks.

MBHD

And what about the LeeLites dragster that revs 8000 without a damper?

Oh now he has a dragster HUm what happen to his race truck????? Sorry i just gota Laugh,No dampener. Yeah thats something I'd try.NOT!!
And If you didn't need one What did all the Makers
use them?????????? Oh Wait i guess that was to just sell you something you didn't need right?? LOL

Calm down, mate.
Its just an example. Your personal business with LeeLites its not anyones problem here.
I don't know what type of chassis he's using or whatever. But he said me he revs 8K in a damperless 292. I don't even know if its true. Never seen it live. But its possible that someone here did. I was just wondering how the things work at 8K without a damper.

Cheers

With Leelites history here, I wouldn't believe anything he said unless I actually saw it for myself. Joe

Gentlemen;

Hank & Larry have been racing these engines and winning for years. If there was ANY advantage to doing it, they would be.

Lee Lites was "run off" years ago. Mostly for parking in the "NO STUPID" zone. :p

Rest assured, if he says; "The 292 in my Dragster turns 8,000 RPM W/O a 'vibration' dampner", there's no such vehicle or event. :rolleyes:

Happy trails to all.

First off seiscanecos74

I have no personal business with mrLee Nore would i ever. As to My comment on the dampener I find it humoris. Thats all.

All the fast guys in Brazil use a damper.
I would not run an engine w/out one.
Some guys there even weld on there dampers as a standard practice.
Even w/a good damper you need to watch for vibrations.

Leelites,called my friends cylinder head shop trying to get info.
He (leelites) was trying to directly compare our 194-292 siamese SP ports cyl heads to a standard SBC port as far as flow numbers,but you cannot compare the two as they are vastly different.

From what my friend disscussed w/him,he really does not know that much about cylinder heads & my friend quickly shut him up,he was lost for words,which is hard to do, but I am/was proud my friend put him in his place(LOST) :-).

MBHD

The Harmonic balancer to use with the inline six is the Innovators West part,
as it is designed for these applications.
I know this,
as the www.inlinesix.com fellows use it and it cured their harmonic problems.
They have taken this GM based engine to 9000+rpm.

They used to have cam gear drive problems etc.
Used to have balancer to crank fretting problems,
went to the Innovators part and cured that deal.

It's not built like the average balancer,
some type of internal clutches.

LHP
www.haywardperformance.com

I have run Fluid Dampers and Fisher units. We now have a ATI Super Damper unit and has worked flawless. The timing has never been rock solid like it is now.

Steven