440 Blocks

Always hear about 440 blocks cracking. Would like to do a poll to see who has personally have/haven't cracked a block. (Cracked caused by stress, etc, not from a rod breaking and going out the side, etc.)

I voted "No", but think it's just a matter of time as I keep stepping up the power level with an old factory block. And that's why I have two spares in garage.

I have an RB that I have used...went 9.0's with nitrous in a 3600lb car. Alum rods, stock stroke and stock main caps
I have been told..."keep it from detonating, it might live"....and " if it don't crack right away, it might last.."

Its sitting in my basement now, and I keep telling myself im going to use that shortblock again someday

I voted NO

275 passes running 8.60’s in my Daytona. 440source assembly and their steel caps. When I tore it down for rebuild it was cracked up thru the mains. It never leaked a drop of water.

I've seen the same thing he has, aluminum rods with a stock stroke OEM forged steel crankshaft cracked between #1 nd #3 cylinders at the bottom of the cylinder walls into the #2 main webbing through it to the bearing surface
I had a OEM 426 M.W. block crack the same place but it broke a rod due to spinning the #1 rod bearing and the rod broke and hit the side of the block on the left front

3 customer motors.

2- 440’s and a 493.

575hp, 625hp, 695hp

And easily a dozen or more cracked stock steel 440 cranks after they’ve been in bracket cars for a while........usually multiple cracks.
Actually....... more uncommon to have it not be cracked.

But when I was running high 9’s with Stock cranks after 3 years when I did a rebuild I stopped even magnifluxing then. They always showed cracks so I just started over with a fresh crank and threw that one on the scrap pile

When you get to the 650-700HP range they will fail. I never blew one up, but when you take them apart to freshen, they have cracks and problems. No 2 main if you use stock caps will always be the one to crack and break. I had one filled with concrete and the cylinders started to fail and it pushed so hard on the concrete it cracked between the freeze plugs, never leaked water and never blew up, but it was junk. Last stock block I did had a main girdle, and filled block with side bolt steel main caps, ran it 4 years, but when I took it apart to freshen, it was cracked along the oil hole that fed the main to the cam bearing on number two main.

I had one crack a main....never exploded. I saw one that split a cylinder wall was .080 at best on one side, when you looked at the boss for the front camshaft bearing the hole was severely of center, I chalked that up to core shift.

I see the pattern of where they can break.
My question: IDT future breakage can be accurately predicted by HP alone. Exactly what factors are involved?
Actual maximum cylinder pressure at highest point too near TDC (like nitrous)
Very low rod ratio (4-1/2" stroke, BBC + .400" rod = 1.45:1)
Knock
Crank stiffness (worse with stroke increase, BBC rod journal)
B size mains (smaller crank, more saddle and cap area) vs. RB (bigger crank, smaller caps)

IIRC generally accepted that supercharged power is easier on the bottom end because the max cylinder pressure is less (than the same power NA) and occurs over a longer rotation period. But how much?

I personally have cracked 2 different stock 440 blocks, couple hundred runs on each i guess. No girdle or block filler. #2 main saddle cracked up into the cyl wall, same place both blocks. Water in the oil the first clue. Did not throw a rod either time. Took it apart as soon as the milky oil showed up. Eagle 4.15" crank, eagle rods, weisco pistons, B1BS heads, Alum main caps both times. 35 deg timing, 9.00 @ 145 2800lbs, 7200 rpm at the stripe.. Put a world block in no more cracks, 8 years later. On a side note I put 600 runs on aa stock block, crank, main caps, no girdle or block fill. But it had aluminum rods, the rods had .25" side clearance from rubbing on the crank sides. You know what the old saying" it is just a matter of time before a stock block fails at higher power levels. John

My 505 cracked the main web after a bunch of 800 hp dyno pulls. The engine didn't leak water and oil pressure was solid but when we pulled it apart for maintenance we could see the crack.

Even using an ARP main stud kit, Upon inspection, my main caps machined mating surfaces, show fretting damage. In other words, the caps are moving. I suspect at high RPM loads in the 675 HP range.
Sold off several stock blocks when the World Blocks debuted. Unfortunately, the World blocks ceased production.

We got a 30+% hit rate on cracked 440 blocks here... definitely not a statistical outlier on the probability.

My guess on the statistics is that a very low percentage of the low hp blocks crack while a very high percentage of the high hp blocks crack. I doubt the curve is linear, most likely exponential. They probably all crack once you get above 900 hp NA. Maybe 50% of them crack at the 800 hp level and 25% crack at 700 hp.

I doubt you'll find caps that don't walk in anything that's being twisted harder than passenger car use.

Unported-1 Indys, stock cross ram, .650 roller, 4.150 Mopar crank, 498, 660hp, never saw 6900rpm. Pulled the front 2 main webs right out of the block. Broke the crank in half right in front of the #3 main.
Doug

voted yes, have had 2 blocks that showed cracks in the main webbing when cleaned up and mag'ed before rebuild both had about 450+ passes on them. The car runs low 10's, probably around 650hp. 4.15 crank, shift at 6200 and trap at 6700 or so. We caught the cracks early, probably no problem for a street car but race??? Who knows.

Thanks for the replies guy. I'm looking to build a 625-650hp engine to help get my car to run 6.50s on a hot muggy day to be able to run a 6.50 index class. I've been running 440's for years but just stock stroke stuff and nothing over the top. I have both 400 and 440 blocks. My gut tells me to go with a 400 block, but my wallet says 440 since I would need less parts. I think I would be fine with a 440 as I'd like it to run on pump gas. I'd like to shift at 6000 and never turn it over 6500. But if it would crack than I'd be kicking myself...Decisions decisions

Don't let worrying about a crack stop you from building something. If an aftermarket block isn't in the budget, then its not in the budget. Don't let that stop you.

My assumption on the % responding 'Yes' is these are all relatively high performance builds, or have had a pretty hard life. I've seen blocks with main studs & stock caps still show obvious signs of cap walk and the engines were (only?) making in the range of 500 to 550 HP.

I don't know if there is an obvious power level where the situation changes from "Yeah, they do that... " to "You better start looking for a new block... soon."

I say build it. And quit worrying about if your block is going to crack.

My first 400 pump gas stroker motor was built with a 4.25 stroke crankshaft from Ohio Crankshaft company with a set of CAT brand 6.800 long BB Chevy H beam rods with a set of Ross dish pistons and a set of 906 iron heads that made exactly 9.25 to 1 compression ratio.
I put a custom(260@.050 intake with .420 lobe lift, 266 @.050 on the exhaust with .409 lobe lift ground on a 108 LSA grind Comp Cams solid roller cam in it. I put a stock type low deck six pack Eddy intake with a set of 1970 440 carbs on it.
That combination made 612 HP @ 5500 RPm and 644 Ft. Lbs at 4500 RPM and help my 3450 Lb. Duster run 10.69 at 124 MPH the first time out.
I race the heck out of that block, it had four sleeves and a welded up deck due to a head gasket blowing out the deck between #4 and #6 I did have a set of Mopar brand Ductile iron main caps and asset of ARP main studs installed in the block to start with
I ended up switching heads and increase the stroke to 4.300 to get the compression up and the car ended up running a best of 9.993 at 134.6 MPH with the air cleaner on and full 3.0 inch exhaust to the rear bumper hook up
My message is the stock 400 blocks will take a lot of beating with decent (under 800 HP) amount of power as long as you get it tune properly Don't let it ping or detonate ever I did let it do that a little on the first combination with the iron heads and it made the main caps fret and walk a little, I dress them up with a good flat file and ran it a lot more, no failures yet as far as I know

If you're worried about detonation (kills engines), mix a little race fuel to your pump gas.
How heavy is your car?

Not sure what your car weights but did you ever consider building a small block stroker engine. 6.50’s is a pretty easy to hit goal and you won’t have to worry about splitting a block. Lighter and easier to work on is an added bonus

Here is the last 440 based engine I built. Was just supposed to be for my 658 D100 but ended up in the kids dragster. Ran great for about 120 runs, run 121 not so much.

3150lbs with driver

At times I"ve thought about that, but I got the car where it's gotten easier to work on with the BB. Plus there's just something about the sound of a BB that a SB can't make.

Mine cracked up thru the mains.
Was racing it that way, found it doing other stuff to it.
Really can't blame the block entirely.
Stickcar,too much clutch. Block had froze and cracked the water jackets years before.
Pounding it in the 9's with cracks on the outside.

LOL. The 121st run was an unhappy run!! I hate to see that, but that is getting pretty thin.

My 505 split the #4 main across the oil feed hole and out to both sides of block . Went up 1 cylinder into water jacket .
10.50/70s . Left at 3500 shifted @ 6000
Ran for 18 months
Machine shop said suprised it happened so soon , tnough also said it really was a "when" issue
I now have a World block , see no value doing the same again possibly with worse results

Tex

Pic


Tex

Just overthinking here.
Of those blocks that cracked, how many were running heads with a stock port window and with a MW port window?

For us, we keep the rpms down to 6500 or less and have no broke one yet....We run a girdle on all our builds.

I don't think it makes a difference. Based on everything described above, my stock-stroke / stock port window 452 RB makes enough power to tell me the fuse is probably lit on the current block already. (Of course, it'll last virtually forever, as long as it's still bolted to an engine stand. )

^^^ I have seen the future... and it ain't pretty.

Medium built .030 over 440 milled and ported 452's, mopar 484 cam, boat anchor l2266f pistons on cast crank with shot peened stock rods/arp bolts. Mains are studded.
Engine is 4spd 4x4, bounced the engine off 6500 rpm a ton in the mud, and its still alive 19 years later.

Cracked 2 440 blocks. They were both stoked to 505 cu. in. 3 years on each, about 400 to 450 passes each. 1st one that cracked hit water. 2nd one was cracked but didn't hit water yet. I think they were both cracked above #2 main. Both shifted at 6100, and went thru the traps at 6600 rpm.

Switched to a Bill Mitchell aluminum block 3 years ago. Between 425 and 450 passes, in 3 years. Was in great shape when freshened up this last winter. Went to 540 cu. in. when we built it with aluminum block...

We are on our 4th year with the 505" 440.

Hundreds of dragstrip passes and 5700+ hard street miles.

It makes ~600 hp n/a and we did quite a few 150hp shot nitrous passes last year. Upped it to 200 this year but not many passes yet because of rain.


I did main studs, stock caps and used a late 70's block with only .030 overbore. Rev limiter is set at 6400 and it never hits that.

The rotating assembly is really light and I'm convinced that is part of what helps it stay together.

Is it because they're like a kid with asthma trying to run?

Ouch


Tex

I ran an injected alcohol 499 low deck for approximately 10 years, 1-300 1/8 mile passes every year, 750ish hp, arp main studs and aluminum main caps, eagle crank, rods and Ross pistons, half fill, finally cracked a cylinder wall on #8...never saw a web crack...shifted at 6800, don't know if it makes a difference but this block was first in a hardtail pipe rack then a 4 link pipe rack, spanned 1998 to 2008. Scattered it all over Denton Dragway after sleeving the cracked #8 hole...( 5 Dyno pulls, 3rd pass down the track) damage was do severe myself and 2 "experts" couldn't figure out what let go first...managed to save the intake, distributor and fuel injection system...oh yeah and valve covers...(most likely suspect was something to do with 7&8 rod journal)...

It doesn’t take much of a small block to make the big blocks look silly. How many 340-360 blocks do you hear about cracking. 😂

This 440 block still ran fine , low 10's , but smoked a bit...

Looks like the number 4 cylinder is cracked WAY up the bore. It must be filled or it would have put coolant in the oil.

#2 ,#3, #4 main saddles were cracked up into the cylinders and the block was getting ready to split in half, no concrete.

When I broke one back in the seventies it was so bad the only thing keeping the back of the block from falling to the ground was because the starter wire was holding it on.

You have to admit, the BBM heads out there aren't exactly setting the world on fire in terms of airflow/cross section. No idea what the Chrysler engineers were thinking really.

No offense intended to anyone with asthma!

I guess it was hemi

those max wedge ports work , nearly as good as a sbc

Tex

# 2 main explosion. 383 600+hp

I have not cracked one, but the highest HP I've put through one at the track was around 620 hp.
It was/is a 14:1 stock stroke 440 that ran 10.40s at 128-129 mph at 3700 lbs. Ran it for a lil over 3 years and never hurt it.
That same motor is in another car but is making around 700 hp now. It is probably a time bomb, but I'll run it til it dies...if I ever get the rest of the car track worthy.

I know Mike Daurity split the main webs and a couple cylinder walls in his low deck 512/400 stroker in his street car '69 super bee a few years ago. It's around 600 hp on motor plus a small plate system.