440 crank bearing clearances?

[Cranky]

More clearance usually calls for heavier oils so, why do that? Heavier weights generally rob power. I always shoot for .002-.0025. And there's plenty of research on the net about oils, oil wedge and clearances.

 

[bm02tj]

To check your bearing clearance have it measured as plastigage is a guide only and not always accurate

 

[not so famous bob]

To check your bearing clearance have it measured as plastigage is a guide only and not always accurate

Street hemi`s came out w/ .003 clearance straight across the board.
At least my two did !

 

[Fran Blacker]

.-.001 u/s journals pictures, the M is to the right of the 5 .

 

[moper]

Oil clearance has to do with expected performance and the oil supply. Plastigage is not an acceptable form of confirmation IMO. Some cheaper gages are available and will be far better to measure and measuring is critical. If you don't do it for a living lesser price point tools will suffice.
I like to keep my street engines between .0015-.0025. I run standard volume pumps and modify the passages, and I measure all the lifter bores so I know the "leaks". Tight's fine as long as there is no taper and steps are taken to verify everything gets fed. Many available stroker cranks have average crank finishing. So you'll see taper and dimensions all over the factory spec when you measure. I've used a bunch of these and I have not had to turn a crank to get it where I thought it needed to be to run safely. If it's a race build, then the larger capacity pan, pickup, and pump, plus larger clearances will be required. Lose is usually faster...lol

 

[stage3]

If you have excessive clearance you will know. If you don't have enough everyone will know. My race motor runs .003" rod/.004" mains. goes hundreds of passes at 7200 with 4.5" stroke. 5w30 synthetic. Indy pump with the relief spring cut down to lower the pressure to 65-70psi@7000 hot.
Doug

hello doug,,,i know its an old thread,,
just picked up my 440 short block from the builder today..was told without input from me, they installed 1/2 groove main bearings because that is what is considered optimum today...is that what u r running? i'm running a dual external milodon oil system with adj pressure valve...mostly street but will track it some,,shift points r 6500...thanks.

 

[wyrmrider]

rod side clearance really does not matter as long as it's bigger than minimum
bearing clearance determines
oils have improved type IV V combos and now even the additive package carrier is full synthetic
0 W oils are SOP now as finishes are better, so are rings
most wear is at start up
remember oil cools so you do want flow across the bearings
so if on the tight side you have to go thinner and if loose then thicker

 

[theman440]

My old 440 had .0025 on the rods and .004 on the mains running a hi volume pump - 80 psi. Had hundreds of 7000 rpm passes on it never had an issue.

 

[dvw]

hello doug,,,i know its an old thread,,
just picked up my 440 short block from the builder today..was told without input from me, they installed 1/2 groove main bearings because that is what is considered optimum today...is that what u r running? i'm running a dual external milodon oil system with adj pressure valve...mostly street but will track it some,,shift points r 6500...thanks.

I've run 1/2, 3/4, no groove. Haven't really seen a lot of difference in my application. Currently 1/2 groove.
Doug

 

[stage3]

mains would probably be fine,,,was thinking the rods only get oil half the time with 1/2 groove mains..to prevent a spun rod bearing.

 

[dvw]

The way to prevent a spun rod is to have properly sized rod bores. Enough bearing clearance (.001"/inch of journal diameter). Keep the oil pick up submerged in liquid.
Doug

 

[stage3]

The way to prevent a spun rod is to have properly sized rod bores. Enough bearing clearance (.001"/inch of journal diameter). Keep the oil pick up submerged in liquid.
Doug

2.7 on the mains and rods,,professional shop that builds race motors did the work,,they did check the size of the rod bores,,crank is chamfered,,so,,sounds like i was concerned over nothing,,i'm running the best oil system,,but i do know that mixing bearing shells is quite common,,thanks.tony.

 

[Challenger340]

Crank Bearing clearances should increase somewhat with pressure and rpm, which typically increase with performance level targeted.
and IMO....
NO.... ".0015" is NOT OK for any kind of performance Engine with increased pressure and rpm ?

No wars wanted..... but for crissakes I wish people would use their melon's for more than growing hair ?
Start thinking "HEAT" in regards to Bearing Clearances..... and not "just" in HOW Bearings cool, but also WHAT causes causes INCREASED Oil Temps ?
geezuz...

 

[Cranky]

Crank Bearing clearances should increase somewhat with pressure and rpm, which typically increase with performance level targeted.
and IMO....
NO.... ".0015" is NOT OK for any kind of performance Engine with increased pressure and rpm ?

No wars wanted..... but for crissakes I wish people would use their melon's for more than growing hair ?
Start thinking "HEAT" in regards to Bearing Clearances..... and not "just" in HOW Bearings cool, but also WHAT causes causes INCREASED Oil Temps ?
geezuz...

What would you recommend?

 

[Challenger340]

What would you recommend?

On What application ? using WHAT Bearings ?
And that's my point...... it changes or "should" change depending on the application and the quality of machining present ?
Cheb 2.200" Rod Journals with less than .0002" OOR and taper ?
Mopar 2.375" journals with less than .0002" OOR and taper ?
Crank journals in either of the above with .0005" OOR & Taper and NO "two" journals the same size ?
amount of side clearance in pairs ?
Tri-metal Bearings ?
B2 Bearings ?
Alecular overlays ?
P Eccentricity Bearings ? H Eccentricity bearings ? V eccentricity Bearings ? M Eccentricity Bearings ?
and....
any of the above in today's "N" designation narrowed bearing that began with the advent of huge Crank Filet radius's because the Chinese couldn't use an Arnold gauge let be GRIND a Crank ?

my point being.... and IMO....
real engine building and machining for the application is LONG GONE ?
just say'in....
If it's gonna get RUN at all I'd rather see a minimum .001" per INCH of journal diameter as a minimum .... than anything less !
and it changes.....
with journal OOR/Taper/Bearing Eccentricity/Material and application/rpm.

 

[383man]

Plastigage is only a quick reference check and you have to use it right to even be in the ballpark. Like make sure all the cranks weight is off the main you may be checking. So if you use it with the eng in a car and your under the eng you have to put shim stock on a couple of bearings to have all the crank's weight pushed up and all its weight off the bearing you check. That puts the crank up against the other side of the bearing so you will be checking all clearance in that journal. Its not perfect at all but I see many use it for a quick check. Ron

 

[Bighead440]

I like full or (lately) 3/4 groove mains with .0025-.003" clearance and minimum .002" maximum .0025" clearance on the rod bearings. I use a HV pump with block oiling passage mods and a 1/2" pickup or preferably external pickup. No thick oil EVER, I like 10W-30 and lately I have done my break-ins (no load) with 5W-30 and zinc additive if flat tappet.

 

[khryslerkid]

While we're talking bearings, I'm planning on changing my oil pan in the near future. I would like to check a couple of bearings while I'm in there.

Is it as simple as removing a cap, inspect, replace and retorque? Or would retorquing change that particular cap and bearing?

 

[dvw]

While we're talking bearings, I'm planning on changing my oil pan in the near future. I would like to check a couple of bearings while I'm in there.

Is it as simple as removing a cap, inspect, replace and retorque? Or would retorquing change that particular cap and bearing?

If you check there is no sense checking one or two. Either check them all or don't worry about it. The mains will be worn on the lower half. The rods on the upper half. You have to roll the uppers out to look. Rolling new mains in the uppers may require dropping all 5 at once along with the rear main seal retainer. A dull tool needs to be used to roll them out to prevent crank damage. Then retorque to spec. Unless you are fluent in engine build practice I'd leave them alone. I've done plenty. It's not impossible but its not something that I think everyone would be comfortable doing.
Doug

 

[Auggie56]

Now I'm confused, a 67' Motors book calls for 0005 to 0015 rod bearing clearance and the same on the main bearings. I have a set of mics that are probably a hundred years old (guessing as there were my grandfathers) the last accuracy check was forty years ago, plus I plasti-gauged both and got three thousand bearing clearance on all journals. At the machine shop, I had the crankshaft polished they supplied a set of bearings. In the real stock configuration, 0003 is enough clearance on both? The machinist when I told him what the book said he replied "That's too much, three to five thousand is more like it. "?????