444 Massey got me thinking

David G · Apr 22, 2020

My 44 EFI has a 3 main bearing crank, extremely long stroke and small valves. OK, I have just explained why I should not have put a bunch of money in it, but my dad and I spent tons of time together on it when I was young. It was also the first vehicle I drove.

So, lets talk main bearings.

I really lugged it down on the dyno when I tuned the EFI, enough it scared me about the main bearings holding up.

I have upgraded the oil pressure relief so it runs 40 at idle and 50 at RPM. I should have plenty of oil regardless of 3 or 5 main bearings.

I am running it about 150 RPM greater, or 1500, but it does have lighter forged pistons. I would assume that there is stress on the crank do to the higher RPM's.

Is there any data on how much torque to put through a 3 main bearing crank?

RCP · Apr 22, 2020

David G

I do not know of any tables or charts for crankshaft stress versus engine torque, it is a pretty complicated calculation typically done with high power 3-D stress analysis.

Regarding engine RPM, I do not believe you are hurting the engine, by using aluminum pistons instead of the original cast iron pistons, you have probably reduced the reciprocating weight by 25% and reduced the inertia load on the rods by 50%. This is very beneficial to rod and rod bearing life. You have offset this benefit some with a 10% increase in RPM, but you are still to the good.

There a few Massey 44 in the pulling word that are bored and stroked and run 30% over on RPM, with very few issues, if that makes you feel any feel any better.

Rich

David G · Apr 22, 2020

Sounds like I am good on RPM.

My H states, do not overload, I am assuming that means do not lug down. I always wondered if I was hurting the engine by testing the lugging down to probably 400 RPM.

Dieseltech · Apr 22, 2020

I have an older MH 44 built years ago that the owner ran about 3000 RPM, he added a four speed transmission ahead of the stock five speed. Engine has an Isky cam, and crank rotating assembly balanced. Neighbor has a White 2-135 with the Hercules 478 cube diesel, seven main crank that STILL broke at the fourth main web area. That's when we found out an older military 6X6 engine crank would fit that had thicker web where the newer crank broke. So, maybe it's a crap shoot that any crank lives..

Janicholson · Apr 22, 2020

Jim's opinion: Over loaded crank shafts break and take the engine out in milliseconds. In a 3 main bearing crank with the typical 1342 order (2134 is the same), the front two , then the back two fire. (primarily to avoid rocking couple vibration from front to back), and with a crank that has no counterweights or dampeners, the sranks are robust enough at the rated rpm, and maybe +10%, but real harmonic vibration can become violent enough to shatter iron when specific speeds and power combine to place transient forces at harmonic locations in the crank. have you broken a stick over your knee and had it shatter there, and at some other location sending pieces flying. It is almost certain that the breakage is not related to static loads. Jim just thinking. With support between each cylinder, the harmonics are dampened to the point that the critical energy needed to shatter the iron is out of the range of possible damage. This is basically true until orbital velocities are reached in racing (real racing) engines are built. Jim

moresmoke · Apr 22, 2020

Just because it is a 3 main crank doesn't mean it is weak. You are making 45 hp with 260 cubes. Think about what some other engines make for power with the same displacement. And how much iron there is in that engine for the power it makes.

Those old tractor engines were designed to lug and be abused. When those tractors were new, the operators were not any sort of power machinery experts. They went out and got work done.

Steve@Advance · Apr 22, 2020

I don't remember what all you did. Other than the EFI, you didn't drastically change the compression, or add a turbo/blower, or any other radical mods did you?

If not, I would not worry about the bottom end at all.

And what do you do with it? Does it get a lot of heavy throttle use? Even if it does, that's what it was made for!

And the RPM increase, that's not much. Think how many farmers unknowing turned one up after the tach broke, probably way higher than that!

Tramway Guy · Apr 22, 2020

Pretty sure that the diesel (HD260) version of the 44 uses the same crank and bearings, so it?s probably oK for a little more stress than what the gas version is doing.

johnlobb · Apr 23, 2020

As I recall, the Ford Flathead V-8 only had 3 main bearings, and they raced a lot of those...

M-MAN · Apr 23, 2020

While it isn't perfect, the best data is from the engine manufacturer. The testing they do give you an absolute safe value on top and bottom speed. A little more either way isn't going to kill it just makes failure a little more likely.

You are correct in worrying about lugging it down to far. The lower the engine speed the harder it hits on the main crank journal everytime combustion occurs. Higher speed targets the the rod journals, but that's more of a weight/balance issue.

Richard G. · Apr 23, 2020

Think of the Model T crankshaft with 3 mains.
All journals were 1.248 inch from the factory.
Ford sold over 15 million of vehicles with these in them.
Cast iron pistons and heavy flywheel with all those magnets fastened to it.
You could break them, but it was rare.
Ford did use extremely good steel though.
My Dad said you ran them wide open where roads would allow.
Mine has been clocked at 45 MPH by folks following me. LOL
Richard in NW SC

MikeJM · Apr 23, 2020

There s no clear answer for any of this.
I ve seen 7 main bearing John Deere s snap a crank and still happily clatter away.

Heard stories of big cube MM s with big strokes flex the crank enough to touch the inside of the crankcase.

Met another fellow that ran an old diesel super stock built on a 401 ford. Spun it fast enough that the crank would flex and grab the rod by the sides. Wasn t fully counterweighted.

The issue with the 3 vs 5 main bearing 4 cylinder or 4 vs 7 main 6 cylinder is not the main bearing itself, but crankshaft flex. Which can show up in the mains.

Take a piece of channel iron and support it at each end and place weight at two places equal from the center, then place a center support and notice how much better it supports the weight.

If you were to increase the mean cylinder pressure high enough and barring any other failures you would eventually break the crank through fatigue. Providing the piston and rods are up to the task as they usually fail first in most cases.
And that doesn t even touch on torsional flex.

444masseyharris · Apr 23, 2020

i would think you are good i run my massey about 3,000rpm and its stock

444 Massey got me thinking

David G

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RCP

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David G

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Dieseltech

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Janicholson

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moresmoke

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Steve@Advance

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Tramway Guy

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johnlobb

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M-MAN

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Richard G.

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MikeJM

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444masseyharris

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