Fixed.
340 Steel Crank
- Thread starter 67_Slimer
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If you're going to use crankshaft at least get it magnafluxed before you pay for it. You're talking about a 60-year-old piece that's been put through hell and back. There's just as many with cracks in them as not. Yes factory crankshafts both cast and forged were good pieces but to compare one to a modern 4340 forged Scat ,Eagle K4 Modular they're different leagues and you pay for it. I understand be true to your school and all but let's be Real.
factory rods will work if properly prepped.
but the cost to do so may be prohibitive in that you can buy new rods that are very strong for about the same or less than having the old ones worked over.
Hellrats
Just another dumbass
I agree but I still use factory rods. Those are tough heavy duty pieces. My machinist still asked me why I won't buy new rods. I tell him because these things are heavy duty. He laughs and agrees. But he does say they are heavy as hell. Just like 340 Pistons. Balancing the assembly is going to cost you more anyway.
gzig5
Well-Known Member
This is the build I did recently that sounds similar to what you are looking to do. Third post has info on piston and rods we used and I bet the same would work well for you. Not a very wild build got good numbers on the dyno.
Stock Stroke 340 Build with NC Engine Builder
Stock Stroke 340 Build with NC Engine Builder
4spdragtop
Well-Known Member
@PROSTOCKTOM will probably know.
I am bein real. A stock Chrysler casting or forging is still superior to any of the brands you mentioned, IMO. They're still made with chinkesium metallurgy. But I agree 100% with having them magnafluxed.
Molnar would be one of the few brands I would get on board with were I to get something new.
Aren't they Chinese? Not a huge deal but just sayin'
Yes, but the finish product is supposed to be better "somehow". Tom has mentioned it before. Maybe we can get him to expound on it again.
Probably like the Chinese made Speedmaster heads. Not bad stuff.
It sounds like the OP found a factory crank. If it checks out it should be plenty fine for what he is building.
Yup. It'll be plenty strong.
33IMP
Well-Known Member
I definitely agree with Mopar Sam! Unless it's. 040 now, I sure wouldn't bore it any more than necessary. The extra 3 or 4 cubic inches are meaningless, the stiffest cylinder walls are WAY more important.
Standard now? Bore it .020 . .030 now? Bore it .040
If it NEEDS to be .060? I'd spring for the lightest custom pistons I could find with the c.r. I want. Any of the custom piston makers can give you what you want.
For a shelf piston? I'd look at Icon.
As for the factory rods. They should be fine, if you're willing to do what it takes......magnaflux for cracks, really great bolts, precision resize, beam polish, and balance.
I have come to the conclusion that I would go aftermarket 4340 H-beams first. Lighter, stronger, Zero cycles vs how many hundred thousand?
Standard now? Bore it .020 . .030 now? Bore it .040
If it NEEDS to be .060? I'd spring for the lightest custom pistons I could find with the c.r. I want. Any of the custom piston makers can give you what you want.
For a shelf piston? I'd look at Icon.
As for the factory rods. They should be fine, if you're willing to do what it takes......magnaflux for cracks, really great bolts, precision resize, beam polish, and balance.
I have come to the conclusion that I would go aftermarket 4340 H-beams first. Lighter, stronger, Zero cycles vs how many hundred thousand?
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Who has the lightest steel rods? How about a forged 273 crank with some lightweight pistons. All close enough to balance with adding mallory metal.
67_Slimer
Real Hot Rods don't shift themselves.
I'm looking at Keith Black Hypereutectic pistons. Anyone know if these are a good option? Street driven looking for a 10.5/1 street/strip kind of build. Part # KB243-.060. Also Aluminum heads, aftermarket rods if they are reasonable.
cookietruck
Well-Known Member
The scat i beam rods..
Scat 2-ICR6123-2124 Connecting Rod, Pro Comp, I Beam, 6.123 in Long, Bushed, 7/16 in Cap Screws, ARP8740, Forged Steel, Small Block Mopar, Set of 8
Top quality racing parts at affordable Poor Man prices. Aftermarket Racing Auto Parts, TRZ Motorsports | Chassis and Suspension | Aeromotive | Fuel Systems | Allstar | Fabrications Parts | ARP | Fasteners | Hoosier | Mickey Thompson | Radials and Slicks Tires
poormanmotorsports.com
33IMP
Well-Known Member
If you ever might consider nitrous, I wouldn't use hyper pistons, but that's just me. I haven't built a non-forged piston motor in twenty or thirty years.
67_Slimer
Real Hot Rods don't shift themselves.
Nitrous would never be an option But Just asking because I have a chance to buy these pistons cheap but was just taking a chance. Unfortunately they aren't getting the reviews I was looking for.
33IMP
Well-Known Member
You haven't mentioned the current bore of your block, at least not that I've seen.
I sure wouldn't bore a standard or .030 block to .060, JUST to use some cheap pistons, hyper, forged or otherwise.
I sure wouldn't bore a standard or .030 block to .060, JUST to use some cheap pistons, hyper, forged or otherwise.
67_Slimer
Real Hot Rods don't shift themselves.
I stated its a .060 over bore
If you run them, I would use the nitrous spec for ring gap.....even if you build naturally aspirated. Just my opinion.
33IMP
Well-Known Member
If it's already .060, no reason not to run the hypers if your not gonna squeeze it. But as RRR says, run plenty of ring gap!
Most of the busted hypers are from people not reading the instructions, running a normal end gap, and the ringlands busting.
Most of the busted hypers are from people not reading the instructions, running a normal end gap, and the ringlands busting.
harvenator
A fish called Wanda
Early 273 cranks were forged. They're out there.
67_Slimer
Real Hot Rods don't shift themselves.
So with everything being said , Stock 340 steel crank , .060 over , Going to have Eddys for heads , Victor intake , 750 QF carb , what do you guys suggest piston/rods setup for my application? I want a very strong bottom end that's not afraid to rev.
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