Too much bearing clearance?
01-06-2007, 07:47 AM
#41
Originally Posted by racer7088
99 per cent of these aftermarket cranks and rods have around .020 -.025 side clearance and if you run tighter oil clearance they will have higher oil pressures. They also are more likely to spin a bearing if they are too tight even though the oil pressure will always show higher when you tighten the clearances up. If you go under .001 clearance and use the right springs you can achieve over 100 PSI oil pressure and can almost blow the filter right off the engine as well as probably spinning all the bearings.
High oil pressure does not mean that you are getting the right amount of oil by the bearings and also does not mean you have the right clearance but rather it is just a measure of restriction and oil viscosity really.
If you run the right clearances you will have lower oil pressure than our example above and also will not have any bearing problems with higher rpm and more power. Oil pressure is a measure of restriction and if you have much higher oil pressure it means less oil is flowing through the bearings if nothing else has changed not more.
High oil pressure does not mean that you are getting the right amount of oil by the bearings and also does not mean you have the right clearance but rather it is just a measure of restriction and oil viscosity really.
If you run the right clearances you will have lower oil pressure than our example above and also will not have any bearing problems with higher rpm and more power. Oil pressure is a measure of restriction and if you have much higher oil pressure it means less oil is flowing through the bearings if nothing else has changed not more.
02-01-2007, 09:47 PM
#44
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We build a lot of circle track engines and we have a few of them near .040 on the side clearance and no oil pressure problems as its the bearing clearance that regulates the oil that flows out between the rods not the side clearance. Now if the side clearance was under .008 it would then restrict the oil and cause the bearings to burn up. You just don't want to expose an oil hole.
We have worked on some wet sump engines with pistons guided rods that have about .100 side clearance and they run the same oil presure as all the other engines. HMMMMMMMMM
Mercedes was the first to come up with the piston guided rod engine years ago.
We have worked on some wet sump engines with pistons guided rods that have about .100 side clearance and they run the same oil presure as all the other engines. HMMMMMMMMM
Mercedes was the first to come up with the piston guided rod engine years ago.
02-06-2007, 09:26 AM
#46
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Originally Posted by SHAKER
.001 per inch of rod or main journal diameter will be just fine. Isn't that what jud would say? I must say I concure. Shaker
-Ben R
