Cast or steel i know its been talked about

[bearman]

Goods and bads on the street 6pac type engine build with cast crank looking for 500 ho and good torque.

 

[lewtot184]

I wouldn't be afraid of a cast crank at that power level. I wouldn't use a manual transmission. good prep is vital. I would use as light of pistons and rods as possible. good balance, proper clearances, good oiling and limit max rpm to something less than 6,000.

 

[bearman]

Thank you for the input the block is 78 440 motor home. The oil webbing is huge going to put 6pac rods and stealhheads from 440 source.pistons not pick out yet but looking for a compression at 10.5 and cam a couple steps higher than the 6 pac one. Has a 727 trans which will be matched up once i get everything in order.

 

[dvw]

6 pac rods will be a balancing nightmare. it'll cost more than you save using the crank. Either stock stuff or aftermarket stuff as light as possible. Strength will be fine .
Doug

 

[bearman]

Thanks will do will start digging into the light weight rods and pistons maybe 440 source would be a good place to start.

 

[wyrmrider]

at that power level stock rebuilt 440 non sixpack LY rods with Direct connection/ Mopar performance SPS rod bolts will work just fine
The TRW/ Sealed Power 6 Pack Pistons are also HEAVY
The motorhome should have had a forged crank but maybe not that late
If you have to buy a crank get a stroker
too much compression for iron heads
a cam two sizes bigger than the 6 pack cam- roughly a 270 will be WAY too big for most street applications
what you can do is go more lift and quicker acceleration than the lazy 6 pack cam
We found that the Mopar Performance cam ONE Size larger cost 60 foot time with stock gears and converter
so work out all of your combination before spending $$$
exactly which heads do you have
the motor home heads should have two small holes on each side of the spark plug for spark plug cooling

 

[lewtot184]

Thank you for the input the block is 78 440 motor home. The oil webbing is huge going to put 6pac rods and stealhheads from 440 source.pistons not pick out yet but looking for a compression at 10.5 and cam a couple steps higher than the 6 pac one. Has a 727 trans which will be matched up once i get everything in order.

if you want pump gas this combo will never work.

 

[wyrmrider]

Let's be more precise
FORGED vs CAST
There are Cast Nodular Iron Cranks and Cast Steel Cranks (Armasteel)
so you can have a CAST STEEL CRANK
btw we made 1,200 hp for 30 minuets and 1,000 hp for 2 hrs on the LA Champion Spark (honest Dick Jones) dyno
one with Armasteel, the other with Cast 52,000 PSI Nodular iron- could not break either one of them
(twin turbos, alky. 210 cu in, 60 lbs boost, stock block and heads too)

 

[bearman]

Well thank you everybody for all the great input. So the best thing to do is just figure out how i want to nuild it and dont woory which crank because they both will do what i need it to do

 

[wyrmrider]

not a boat, not a hd truck, not circle track like sprint car- you are good to go

IDK about double keys for blower with cast crank
anyone?
I had a Micky Thompson cast stroker in a 392 in a flatbottom- crank broke right at the last bearing
it idled us back to shore but would slip with any power MT gave us a new one and raised hell with the supplier- no more problems. I think that was one of the first aftermarket cast cranks- oh and the rods were boxed- heavy MT had us go with his aluminum- gave them to us- could have been the problem

 

[BSB67]

Let's be more precise
FORGED vs CAST
There are Cast Nodular Iron Cranks and Cast Steel Cranks (Armasteel)
so you can have a CAST STEEL CRANK
btw we made 1,200 hp for 30 minuets and 1,000 hp for 2 hrs on the LA Champion Spark (honest Dick Jones) dyno
one with Armasteel, the other with Cast 52,000 PSI Nodular iron- could not break either one of them
(twin turbos, alky. 210 cu in, 60 lbs boost, stock block and heads too)

Thanks. And while we're at it, the heads are cast iron, not steel.

 

[rumblefish360]

a cam two sizes bigger than the 6 pack cam- roughly a 270 will be WAY too big for most street applications

270* advertised duration?

Let's be more precise
FORGED vs CAST
There are Cast Nodular Iron Cranks and Cast Steel Cranks (Armasteel)

What is and by whom is Armasteel?

 

[biomedtechguy]

What is and by whom is Armasteel?

Pontiac. "Armasteel" name was cast into the cast iron crank in the 4 bolt main 421 in my wife's GTO motor, as well as the stock replacement I bought for it when it was rebuilt 2 years ago...we decided not to make it into a stroker motor.

 

[rumblefish360]

Pontiac. "Armasteel" name was cast into the cast iron crank in the 4 bolt main 421 in my wife's GTO motor, as well as the stock replacement I bought for it when it was rebuilt 2 years ago...we decided not to make it into a stroker motor.

Ummmm, OK, I’m a little confused. Is Armasteel available for the MoPar camp?

 

[wyrmrider]

our motor was a 199 AMC 6 3" stroke also 3.5 in stroke for the 232
AMC used both ARMASTEEL (try google) and 52000psi cast nodular iron
we could not break either of them
as posted above ARMASTEEL was cast into the crank
IDK what Thompson used- his shop was nearby and he was a pioneer in many ways.
His Hemi heads were cast so they could be drilled for most any 4 bolt per cylinder block- most famously for the Pontiac but there were others. Ford FE
IDK about OLDS , CAD etc

 

[747mopar]

if you want pump gas this combo will never work.

What is it your referring to as far as it not working?

 

[wyrmrider]

I meant the 6 pack cam is roughly a 268-270 seat timing and that two sizes bigger would be a disaster
but it's lazy, not much "intensity"
also wide LCA like 115 to cover up the long lazy ramps and still give some idle and vacuum
but still has way too much overlap for that size of cam- makes the exhaust run HOT and blows your intake out your exhaust reducing gas mileage
all smog stuff
not exactly something you want to emulate
that Comp HE 274 would be about one size bigger but I'd want 3:54
taller than that I'd want shorter cam
with low compression and 2.xx gears I'd want under 260- with high ratio rockers
Comp has these lobes listed under 4x4, or see Bullit, Howards, Engle, Crower, (most are not in their catalogs)etc
best at 256 us Mike Jones asymetrical .305 lobe lift,still easy on the valvetrain

 

[wyrmrider]

re: 747MOPAR's comment/ question
about "that combo will never work

First the mechanical
Balancing a cast crank motor with the unnecessarily heavy 6 pack rods and heavy pistons
neither the 6 pack or cast crank dampener would be right and the weighted B&M Flexplate would just be a start at the back end.
IDK about heavy Mallory metal
with a cast crank balance
lots of wasted money and a dead end performance wise
Now the combustion chamber
First thing to do with a MOPAR is figure out how to get some quench- it makes the rest of the build so much more responsive, less timing, less picky on fuel octane, less pinging and detonation, etc
Several ways to do this but easiest is wedge closed chamber heads and some 0 deck pistons with a deep dish (depending on what compression you're
going for
This analysis is done at the same time as the stroke decision
Then head flow requirements
then cam
and if cam does not match converter and gears and usage then go around the list again- it's iterative
three budget items
rotating assembly including balance
heads and induction (including the FI decision)
Cam and valve train
all have to work together
cheers

 

[rumblefish360]

our motor was a 199 AMC 6 3" stroke also 3.5 in stroke for the 232
AMC used both ARMASTEEL (try google) and 52000psi cast nodular iron
we could not break either of them
as posted above ARMASTEEL was cast into the crank
IDK what Thompson used- his shop was nearby and he was a pioneer in many ways.
His Hemi heads were cast so they could be drilled for most any 4 bolt per cylinder block- most famously for the Pontiac but there were others. Ford FE
IDK about OLDS , CAD etc

Looked up “ARMASTEEL” and found nothing related to or for use in a MoPar. Just GM stuff.

 

[wyrmrider]

http://amccars.net/cgi/yabb2/YaBB.pl?num=1194214266