Small block lubrication path?

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dibbons

dibbons

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I just noticed the #1 main bearing saddle has "three" oil hole passages (not "one" like the other saddles). I become easily confused when trying to interpret those oil path diagrams/sketches with the arrows going every which way.

Is someone out there qualified to explain in plain English, the path(s) the oil takes in a small block Mopar from oil pickup screen to falling back into the oil pan. Please no sketches or fotos, just tell me how it is! Thank you.

oil filter.jpg
 
From filter, through main cap, out to filter, through filter to RH main lifter gallery, down from lifter gallery to each main bearing, on the front cap it goes down to main, and feeds back up to LH lifter gallery
 
That's a big reason it's important to make sure the lifter bores are sized correctly, because you have 16 "leaks" in the supply before it gets to the bearings.
 
Pretty much, the mains feed oil up to the cam, the cam journal then is timed to deliver oil to the rockers
 
As above... the rockers and then the pushrod cups for the adjustable type rockers are last place. The oil supply to the rockers is limited to just a few percent of the time by the oil flow via holes THROUGH the cam. Think of it as a 'pulsed' oil supply.
 
nm9stheham said:
As above... the rockers and then the pushrod cups for the adjustable type rockers are last place. The oil supply to the rockers is limited to just a few percent of the time by the oil flow via holes THROUGH the cam. Think of it as a 'pulsed' oil supply.
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And since it's a time limited system, as the RPM goes up you have less time to get oil up there. That's why you should NEVER restrict oil to the top end of a SBM.
 
Everything is crystal clear, except for one little doubt. Does the valve lash clearance in a solid camshaft make it easier to lubricate the pushrod/rocker arm contact point?

I was thinking, when we convert to adjustable 273 rocker arms and use a hydraulic camshaft there will no longer be any valve lash gap as soon as the lifters pump up at start up. Wouldn't that oil starve the pushrod/rocker arm contact point a little?
 
in pickup thru oil pump-thru #5 main cap-out to filter-in directly to passenger side lifter galley and #5 main bearing and pressure sending unit. passenger lifter galley feeds 4, 3, 2 and 1 main bearings which goes thru crank to feed rod bearings, and up from #4 main to feed passenger rocker shaft and #4 cam bearing. up from #3 main to feed #3 cam bearing. from #2 main to feed driver side rocker shaft and #2 cam bearing. up from #1 main to feed #1 cam bearing and driver side lifter galley. adjustable rockers that have a ball end adjuster and a pushrod with a cup up top are cool cuz the pushrod cup holds oil.
 
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dibbons said:
Everything is crystal clear, except for one little doubt. Does the valve lash clearance in a solid camshaft make it easier to lubricate the pushrod/rocker arm contact point?

I was thinking, when we convert to adjustable 273 rocker arms and use a hydraulic camshaft there will no longer be any valve lash gap as soon as the lifters pump up at start up. Wouldn't that oil starve the pushrod/rocker arm contact point a little?
Click to expand...
Are you thinking that the tiny clearance between rocker and shaft when the valve is closed will allow a bit more oil to get out? It won't make a difference if the shafts have the 2nd oil hole up on the adjuster side. (And oil will work it's way in the gap at the bottom even with a hydraulic lifter.... oil just does that! The same situation exists with the stamped rockers....)
 
yellow rose said:
And since it's a time limited system, as the RPM goes up you have less time to get oil up there. That's why you should NEVER restrict oil to the top end of a SBM.
Click to expand...
The way I look at that is not that it is time limited per se... the % of time the opening for oil flow is there stays constant regardless of RPM. But, with the cam 'flow interruptor' in place, the oil has to accelerate from a dead stop each time the cam opening lines up. That takes a finite amount of time to get the oil to flow each for each opneing, and as the opening time gets shorter and shorter with higher RPM's, eventually the oil never can really get flowing at each opening...... hence rocker starvation.

It is really the same as the engine 'starving' for fuel-air mixture when the RPM's go above a certain limit..... the fuel-air mix has to accelerate from a dead stop for each cylinder fill cycle, and eventually, at high RPM's, there is not enough valve-open time to get it moving each cycle.
 
nm9stheham said:
The way I look at that is not that it is time limited per se... the % of time the opening for oil flow is there stays constant regardless of RPM. But, with the cam 'flow interruptor' in place, the oil has to accelerate from a dead stop each time the cam opening lines up. That takes a finite amount of time to get the oil to flow each for each opneing, and as the opening time gets shorter and shorter with higher RPM's, eventually the oil never can really get flowing at each opening...... hence rocker starvation.

It is really the same as the engine 'starving' for fuel-air mixture when the RPM's go above a certain limit..... the fuel-air mix has to accelerate from a dead stop for each cylinder fill cycle, and eventually, at high RPM's, there is not enough valve-open time to get it moving each cycle.
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It's just like oil to the rods. It's timed. As RPM goes up, there is less time to get oil to the rods. Same with the rockers. It's simple math if you want to do it.
 
No math problems on this end..... If you double the RPM's, the time duration of each opening is halved but there are double the number of openings, so the total 'oiling opening' time stays constant.

It is just the length of the individual openings gets too short for the oil to get flowing.
 
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