Quick question

[SimDog]

Is using a forged crank over a cast crank worth spending $150? Going to be building a 78 RV 440 to approximately 500hp and plan on using stock rods already in the motor.

Thanks in advance for the replies!

 

[mopar 3 B]

Cast cranks are said to be good to 600hp. But some here will not agree.

 

[HT413]

It’s not worth it at all, yet I made sure to use one in my 451 probably same hp levels.

Didn’t help did I.

 

[dvw]

All depends on Balancing. Cast crank requires offset flex plate from B&M (Or a specially weighted converter/flywheel) and a Cast Crank Damper. I'm not sure if it's possible with a light rotating assy to get close enough to go to neutral balance. The crank itself should be fine. We put over 800 through a stock 360 cast crank. So do you need to purchase flexplate, balancer? add up the cost and see what works best.
Doug

 

[SimDog]

Cast cranks are said to be good to 600hp. But some here will not agree.

I have heard that as well. That Mopar made the strongest cast crank out there.

 

[SimDog]

All depends on Balancing. Cast crank requires offset flex plate from B&M (Or a specially weighted converter/flywheel) and a Cast Crank Damper. I'm not sure if it's possible with a light rotating assy to get close enough to go to neutral balance. The crank itself should be fine. We put over 800 through a stock 360 cast crank. So do you need to purchase flexplate, balancer? add up the cost and see what works best.
Doug

I have a complete 440 from the RV with the auto trans that was attached. If I purchased the forged crank, what would I need to buy to make it work? I also have another '68 727 trans with the correct tail shaft for a car.

I guess what I am wondering is, will the motor be better balanced and stronger with the forged crank?

 

[mopar 3 B]

Rods, vibration damper and pistons. The 68 trans would have the correct torque converter for the steel crank.
Depending upon the year of RV trans which would have the heavier parts. The tail shaft and first - reverse hub may not interchange to get the long tail housing required. That change would be in the 76-77 model year.

 

[RT K_line]

I have used a cast crank with the heavy 6 pack rods and pistons in an engine I had to rebuild. I didn't have it balanced either, it had a vibration at 3000 rpm but I ran it like that anyway. It was before I knew that the 6 pack engine had special internal parts. It never failed even though I hit 7000 rpm a few times by accident and regularly wound up to 6500 rpms. Use it with confidence I'd say.

 

[HT413]

cast crank is lighter but needs to be externally balanced. So converter and dampener have weights on them to complete the balance of the rotating assembly.

Forged crank is heavier but has the benefit of being internally balanced, so dampener and converter don’t need weights.

If you go with the cast crank, and believe b&m and others make a weighted flex plate so you can use any neutrally balanced converter if you prefer.

 

[gkent]

Strong enough ... have you ever seen the videos of that early '60's 4-door B-body with the twin turbo big block ? The thing is making over 1000 HP ... with a cast crank !!!

 

[oldbee]

For my “old school” piece of mind- forged all the way if only $150. IMHO!

 

[SimDog]

Strong enough ... have you ever seen the videos of that early '60's 4-door B-body with the twin turbo big block ? The thing is making over 1000 HP ... with a cast crank !!!

Awesome! I guess I'll stay with the cast crank and get a weighted flex plate. Sounds like the least challenging way to go and less expensive as well.

 

[gkent]

Ok, I lied. Its a small block and not that much HP BUT it still has a cast crank !!

 

[dvw]

I have a complete 440 from the RV with the auto trans that was attached. If I purchased the forged crank, what would I need to buy to make it work? I also have another '68 727 trans with the correct tail shaft for a car.

I guess what I am wondering is, will the motor be better balanced and stronger with the forged crank?

Either can be balanced. What kind of rods/pistons are you going to use? Match the harmonic damper and flex plate/converter that came with the crank. Either converter will work if used with the correct flex plate. Harmonic damper must match the crank. Cast damper says "Cast" right on it. The 62 posted above is my sons.
Doug

 

[SimDog]

Either can be balanced. What kind of rods/pistons are you going to use? Match the harmonic damper and flex plate/converter that came with the crank. Either converter will work if used with the correct flex plate. Harmonic damper must match the crank. Cast damper says "Cast" right on it. The 62 posted above is my sons.
Doug

I am going to use the stock cast crank and six pack rods. Here is the rest of my setup: Sealed Power L2355F cast Pistons, ProMaxx heads w/84cc chambers, 210cc intake ports, 214int/181exh valves, Edlebrock 7193 intake. Have not decided on a cam yet, could use some suggestions on that. Want a streetable but also want some lope in there. The 62 looks awesome!!!

 

[gkent]

Ditch the 6-pack rods and go with a standard rod - much less weight. Also I just can't see the point of 6-pack rods with a cast crank. If anything, the cast crank would be the weak link in your chain, not standard rods.

 

[moper]

Ditch the big rods and run LYs, and have the crank internally balanced. It will cost a little more, depending on the piston choice because you will need to add weight to the crank and it's not cheap.

 

[dvw]

I am going to use the stock cast crank and six pack rods. Here is the rest of my setup: Sealed Power L2355F cast Pistons, ProMaxx heads w/84cc chambers, 210cc intake ports, 214int/181exh valves, Edlebrock 7193 intake. Have not decided on a cam yet, could use some suggestions on that. Want a streetable but also want some lope in there. The 62 looks awesome!!!

That combo of rod and crank is an oddball. Stock balance will not apply. The six pack rods are heavier (aprox 85 grams) than the stock LY rod (and no stronger). Your L2355F is about 25 grams lighter than a stock piston. The pin that is supplied with it is 25 grams heavier so its equal to a stocker. A little lighter on the Bob weight isn't a big deal, heavier can be. The cast crank rods would be a better choice. Or a set of aftermarket rods. They aren't much more than rebuilding a stock set with new bolts. Especially if your not balancing the assy. Cam choice will require vehicle type, converter choice, gear information.
Doug

 

[Garys1969RR]

Awesome! I guess I'll stay with the cast crank and get a weighted flex plate. Sounds like the least challenging way to go and less expensive as well.

If the motor has a cast crank already, then you have the correct balancer and pulleys for the alternator and water pump. The balancer is about 2" thick, where the forged crank balancer is about 1" thick. So if you went forged crank, you would most likely be looking for different pulleys too. With the cast crank you will only need to have the properly weighted torque converter. Or you can use the un weighted torque converter, and use a weighted flex plate with it. Available from Summit, I'm sure. A cast crank should be good to 600+ horsepower.

 

[SimDog]

So here is the consensus. Stick with the LY rods, and possibly have the crank internally balanced.

I do plan on doing all new ARP studs/bolts everywhere for strength. Both the intake manifold and heads will be port matched for better flow.

Vehicle is a 68 Charger, 8 3/4 SureGrip 323 gears and a 727. I have been looking at the Edelbrock 7194 for the cam. Thoughts?