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440 crank bearing clearances?

polkat

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The book calls for .0015" on both mains and rods. Some folks suggest that if the engine will see any high rpm use, to add a bit of clearance. The engine is being built for street/strip (and most of that street). What clearances do folks here suggest?
 
.0015" - .0025" is good. An old rule of thumb suggests .001" per inch of journal diameter.

I even ran as loose as .006" (as checked with plastigauge) and nothing bad happened, however I'm not recommending that. It was an eye opener to lay down a strip of green plastigauge, torque the cap, and find the strip still round!
 
Yea, Meep, I think I might have asked this before because I am getting about .0025" everywhere with Plastigauge, and I thought maybe I should tighten it up with .001" undersize bearings. I had suspected this crank might have been cut .001" under at the factory (some where) although the block does not have the malteze marking for that (could be it's not the original crank though). So you think that as loose as .0025" would be okay?
 
.0025" is fine. I'm at .003"

Run a high volume oil pump and a pan with a little extra capacity.

Loose is good (to a point).
 
Yeah, .0025" is fine for a MoPar. Running a high volume pump MAY help IF the oil demand is high, otherwise the extra volume just goes out the pressure relief valve. I have a standard volume pump with a 70 lb spring on mine and I think I'm at .002" - .0025". The Maltese Cross marking I believe means .010" under, not .001" under.
 
I concur, rods and mains .0025-.003, and make shure rod side clearance is no more than .017. High volume oil pump and 6qt oil pan.
 
I realize this is an old post , but can anyone concur the rod and main bearing clearances using plasti gauge on a 440 -bored .060 with a high volume oil pump .
 
432 Stroker

440 Source Kit

Block was line bored , using 440 Source billet steel main caps

IMG_0090.JPG IMG_0091.JPG
 
I'm running .002 - .003 , standard factory 440 journals. I have 85 psi cold and almost 60 psi hot with a high volume pump using 10/40 full synthetic
 
Yeah, .0025" is fine for a MoPar. Running a high volume pump MAY help IF the oil demand is high, otherwise the extra volume just goes out the pressure relief valve. I have a standard volume pump with a 70 lb spring on mine and I think I'm at .002" - .0025". The Maltese Cross marking I believe means .010" under, not .001" under.
Had a Maltese cross on a motor crank was -.001 number 5 main and -.001 5/6/7/8 rod journals. Crank was stamped outside of a counter weight M 5 R 5 6 7 8. So you need to check the crank. Can supply a picture if needed.
 
Had a Maltese cross on a motor crank was -.001 number 5 main and -.001 5/6/7/8 rod journals. Crank was stamped outside of a counter weight M 5 R 5 6 7 8. So you need to check the crank. Can supply a picture if needed.
yes , i would like to see that pic . thank you
 
Gentlemen,
My 2 cents worth...
I'm running 0.002" - 0.0025" on both main and rod bearings. I use full groove main bearings (Clevite 77 tri metal steel backed babbit with copper tin overlay). This provides 360 degree oiling of the rod bearings. I have used plastic gauge but prefer "miking" the journal O.D. with digital calipers and the corresponding bearing cap I.D. with the bearings installed. The difference in diameters is the bearing's clearance. It goes without saying that that the cap screws/bolts/nuts are torqued to specs. To get full groove mains, I buy 2 sets any only use the top half shell in both the upper and lower cap, AFTER removing the tang on the lower shell. Then increase the main cap torque by 10 additional pounds over stock. This yields in more "crush" to prevent the bearing from "spinning". I use a high VOLUME oil pump and 10W-30 MobliOne - 75psi hot oil pressure at 3000 RPM and 55psi hot at 1200RPM idle. I run an additional quart of oil, because of the hi volume pump
This is what works for me....i'm sure others have their own methods and opinions.
Bob Renton
 
switch to 0W-40 Euro spec fully synthetic "oil" (actually made from natural gas) Mobil 1- Penzoil etc
will really help that cold pressure and flow
usually expensive but walmart sells for under $25 for 5 quart jug better base stock requires less additives/ modifiers and does not shear down nearly as much
.003 on the mains .002 on the rods lots of time
do not sweat it as much on a MOPAR as on a SBC or BBC as the crank does not move around as much
with more clearance do not increase the bottom number but you can increase the second number- 5W-30 to 0W-40 for example
20W-50 is a non starter except in the warmest of climates- most wear is when cold and 20w just does not flow when cold
 
432 Stroker

440 Source Kit

Block was line bored , using 440 Source billet steel main caps

View attachment 569378 View attachment 569379


Same here as I use a 440Source crank and their billet steel main caps. Mine are all at .0025 to .003. I use Valvoline 20W-50 VR1 racing oil and even hot at an idle it carries about 40 lbs at idle and about 70 driving down the road at higher rpms. Ron
 
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
 
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