Internally Balance Cast Crank?

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And I learned, after I posted the price of summits p/n of their 285 greatest cam and price, $118 . A few days later Summit rises the price to $178...mmm ,what's that tell you? People out there took the info and started buying them all up. Sincerely Jesse
 
summit just raised the prices of all their cams , that deal is over.
 
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Back in the early seventies my brother had a nice Aussie VC Valiant with 273and he added a edelbrock LD4B manifold, Holley carb and headers and it ran great for a few years.
After a few years he broke a crankshaft. He then put a 1968 hi comp 318 in it with just the for mentioned add ons.
Man that thing was quick. He used to run GT Falcon 351s and regularly knock them off!
As the thing had a standard cam in it and would idle like a std car, when he would line up next to the GT Falcon 4 speed manual his std looking and sounding Valiant would get Jeers but silenced a lot of people after they saw how it ran.
Now back to the 273. That would of had a forged crank in it so it must of been highly unusual to break one of those.
 
Jessearent said:
I learned cast crank is lighter than forged, cast aluminum pistons are heavier than forged, mopars 318/340 3.58" throw cast crank "might"require balanceing. And Scats cast 318/340 3.58" is already internally balanced as is. Therefore an economical desicion would be to - go with the Scat cast crank and forged pistons keeping the assemble lite as possible. And H beam rods are roughly 700 grams bushed and Scats are 643 grams. I know you don't believe it, but I would put this lite rotating assemble in my engine and use the neutral balancer on front and not pay for t machine shop...figuring a bob weight ect. Figiting over the last fews grams of unbalanced weight somewhere. Sincerly Jesse
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Strange, not getting a negtiive response on the above statement. I must of got it right
 
AJ/FormS said:
No the factory 360 crank does Not fit into a 340, and
if it did, it would punch the pistons up out of the bores by half of the stroke difference.
The rod castings are the same put the 340 has floating pins versus pressed pins for the 360.
And that pretty much makes the balance question moot; but again, the 340 forged cranks were balanced for the factory 745? gram pistons versus IDK 505? grams for the 360 pistons, so no, a rebalance would be required.
I wouldn't put any non-stock engine together without balancing it. I hate doing things twice.

But
many years ago, Chrysler sold 3.58 stroke cranks that dropped right into any 3.315 stroke saddles, 3.79 cranks too.
A 3.79 in a 3.94 bore/318 comes to about 370 cubes, about the perfect size for an A-body. I bet I could suck close to 28 mpgs out of one of those by building it to cruise down at around 65-1800 rpm. It would, of course, need either a manual trans with overdrive, or an A500/518
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Got it AJ, but I was thinking about Scats internally balanced cast crank , there 318/340 journal size with there stroke of 3.58" . Sorry I didn't make my self clear.
 
Jessearent said:
Curious, can you mix and match cast cranks,3.58" throw with forged flat top pistons in a 340 with H rods, and get away without balanceing it? Would it be coincided internal or external balance?
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Hey do yourself a big favor and get any combination balanced. I have seen your comments about this subject in other threads and the only way to do it right is to get the components balanced when ever you change anything. Got it? If you want to throw it together in your barn with what ever and however then go for it but don't waste our time with questions.
 
Why don't you do something constructive, like call a machine shop and talk to main machinist, ask him the width and depth of the holes he drill in the counter balancers and which ones, for an internally balanced cast crank, like Scats 340/3.58" throw and provide him with my forged piston weight icons 741 360 piston .070 over with pin wt and my 715gr H rods....and post me an honest answer.
 
Jessearent said:
Why don't you do something constructive, like call a machine shop and talk to main machinist, ask him the width and depth of the holes he drill in the counter balancers and which ones, for an internally balanced cast crank, like Scats 340/3.58" throw and provide him with my forged piston weight icons 741 360 piston .070 over with pin wt and my 715gr H rods....and post me an honest answer.
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Call a macine shop? Yes, that's exactly what you should do.
 
Jessearent said:
Why don't you do something constructive, like call a machine shop and talk to main machinist, ask him the width and depth of the holes he drill in the counter balancers and which ones, for an internally balanced cast crank, like Scats 340/3.58" throw and provide him with my forged piston weight icons 741 360 piston .070 over with pin wt and my 715gr H rods....and post me an honest answer.
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do you have any idea just how many veteran machinist are on this website and have responded to your questions only to have you respond thay dont know or should be more open minded???? any idea how many veteran engine builders on here??? its great to see your enthusiasm and try to think outside the box but machine work is very very exacting and highly skilled work! and short cuts that work are bout non insistent! this stuff cost to much to start with, cost alot more to redo the 2nd time! like she said, slow down, take your time, and do it right!
 
It seems to me that you're trying to re-invent the wheel, but from the position of not knowing what a wheel looks like, nor having the equipment to build it..
I have seen engines that shook badly from idle to cruise-rpm, then smoothed out some at rpm . Eventually, something breaks, and not always in the engine either.
And
then there is my professionally balanced engine, that is smooth as glass, and revs effortlessly to past 7200...... so much so that I had to install a rev-limiter, cuz, as a streeter, I can't both drive and watch the tach at the same time. Mine is a 4-speed, and she whams thru gears pretty rapidly. and, this engine now has over 100,000 miles on it, and is still a strong runner.
I imagine you can build your engine any way that you want to, but when you gotta put new rod-bearings in it every winter, that should send up a redflag, like, right away.
If you don't want to balance the assy, just buy a pre-balanced kit.
Or better yet, pick up the phone and call a vendor for a drop-in with a warranty. Let the guys with the equipment make your parts play nice together.
Then, you can have the pleasure of installing the bolt-ons, knowing the engine is gonna drive for many many years; or at least has the potential to.
BTW-1
my pistons are cast hypers circa 1999, the bushed rods came out of a late 60s 318, the factory flywheel is off a 1970 340, and the harmonic balancer is off a 71 360, which also donated it's block and cast crank. Jus saying. When I sent the parts out for balancing, I never even asked beforehand, what it would cost. It had to be done, so the cost was whatever. I've never been sorry.
BTW-2
The missed-shift event that precipitated the buying/installing of a rev limiter, was when I saw the tach needle crossing the 8000 line, coming down. That was some 18/20 years ago, and the engine never missed a beat. Somewhat ironically, I rebuilt the shifter and have never missed another shift with that shifter.
 
65 Dartman said:
Both the 70 forged crank and the one out of this 73 block have "a nice resounding tiiing" -- unmistakable! FWIW the pistons are the nice high compression 69/70 pistons, which the PO mentioned prior me buying the short block.
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The 73 340 Block, in my 74 Duster, has a forged Crank. Doubt it left the Factory that way, but it DEFINITELY has A Forged Unit. I picked up the short block, ready to roll, from a Mopar Man with a 10 second street dart. Ex Army Helo Mech. When I called him and mentioned I pulled the Solid Cam out, he Screamed " What the Hell did you do to my motor? It's a Small Block Dammit!" He had his own shop as a Business also...
 
AJ/FormS said:
It seems to me that you're trying to re-invent the wheel, but from the position of not knowing what a wheel looks like, nor having the equipment to build it..
I have seen engines that shook badly from idle to cruise-rpm, then smoothed out some at rpm . Eventually, something breaks, and not always in the engine either.
And
then there is my professionally balanced engine, that is smooth as glass, and revs effortlessly to past 7200...... so much so that I had to install a rev-limiter, cuz, as a streeter, I can't both drive and watch the tach at the same time. Mine is a 4-speed, and she whams thru gears pretty rapidly. and, this engine now has over 100,000 miles on it, and is still a strong runner.
I imagine you can build your engine any way that you want to, but when you gotta put new rod-bearings in it every winter, that should send up a redflag, like, right away.
If you don't want to balance the assy, just buy a pre-balanced kit.
Or better yet, pick up the phone and call a vendor for a drop-in with a warranty. Let the guys with the equipment make your parts play nice together.
Then, you can have the pleasure of installing the bolt-ons, knowing the engine is gonna drive for many many years; or at least has the potential to.
BTW-1
my pistons are cast hypers circa 1999, the bushed rods came out of a late 60s 318, the factory flywheel is off a 1970 340, and the harmonic balancer is off a 71 360, which also donated it's block and cast crank. Jus saying. When I sent the parts out for balancing, I never even asked beforehand, what it would cost. It had to be done, so the cost was whatever. I've never been sorry.
BTW-2
The missed-shift event that precipitated the buying/installing of a rev limiter, was when I saw the tach needle crossing the 8000 line, coming down. That was some 18/20 years ago, and the engine never missed a beat. Somewhat ironically, I rebuilt the shifter and have never missed another shift with that shifter.
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Ok I will do the balance . Will I need need much removed from a 4" forged crank in a 360 if I use heavy old trw L2405f pistons? Will these old pistons clear the crank?
 
whats the compression height? 4 inch crank gonna want something like 1.45ish where a 3.58 wants a 1.65ish or youll have a positive deck height, witch is ok long as rings stay in block and useing open chamber heads....
 
Just as a side note, I asked a machinist about the scat 9000 series cast crank and he said, those crank always require heavy metal added.
 
dirty white boy said:
whats the compression height? 4 inch crank gonna want something like 1.45ish where a 3.58 wants a 1.65ish or youll have a positive deck height, witch is ok long as rings stay in block and useing open chamber heads....
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Thx dirty WB I got a set of 302 castings with open chambers and 2.02" valves added. I will keep an I on the compression height.
 
302s are closed chamber 318 heads, lotta love, lotta hate for them, then theres 308 360 heads thats real hood heads thats open chambers!
 
I rarely post anything on this site, but for anyone looking for the cutoff date for 340 forged vs cast crankshaft, it is in this TSB. Most of the 1972 model year had forged crankshafts as described in this bulletin up to April 11,1972. The engines from April 11 thru probably July 1972 had cast cranks. I didnt work for Chrysler but did for GM. That’s typically the time frame in those years for model changeover.
I have a 1972 built in March 72 and it has a forged crank.

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Alright, I will double check the casting # when I get home....I remember they are 30 ...something with good flowing exhausts. Pss. Someone needs to fix the post reply button on this software.
 
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