controlling top end oil flow

[clutchdust]

I'm planning on making the switch to full roller rockers when I install the AFR heads later. One of the things I want to do though is reduce the amount of oil pumped up to the top of the engine, thereby reducing the amount that has to drain back. I know that even with full rollers I'll still need some oil for basic lubrication and to help cool the springs and valves but the SBC heads really don't have the best oil drain back scheme ever devised. To that end, I would like to reduce the amount pumped up there to start. While trying to think of a way to restrict the flow it occurred to me that the lifters are nothing more than hydraulic pumps anyway, that's how the oil gets to the top of the engine to start with. So I'm wondering if you can control the amount of oil volume in the top of the engine by the amount of preload on the lifter. My thinking is that if I tighten the lifters down more than normal, say to about 1 turn before the valves don't seat, that I will reduce the volume the lifter is available to hold, resulting in less oil pumped up the pushrod.
Sound reasonable, or am I all wet?

 

[Carb Doc]

The set of hydraulic lifters is a clearence issue not an oil control issue. DO NOT screw with this. Set them where they belong. if you intend to get good longterm use out of your valve springs I would not even think of restricting flow that is necessary for rocker lube and Valve Spring Cooling. Not hard to ruin a good set of springs in a very short time if not properly cooled. Record your seated spring pressure when you install the head with the new rockers and measure them again next year, you will not be too impressed to see that they have likely lost 30 or more pounds of seat pressure. If this is just a hydraulic cam it may not matter BUT if a Hyd Roller or worse yet a soild roller . these things live and die on Seat pressure. COOLING of the springs is a MUST. If you are worried about oil drain-back clean out the oil drain back holes on the ends of the heads and around the push rod area, this will help. Remember OIL is the Life Blood of your Engine.

 

[mrvette]

I wasn't going to sound off on my own, but I agree with Carb Doc.....

GM guys been at ENGINEering for a lawng.......time....:lol:

 

[clutchdust]

OK, I don't have a problem with that but is there a better way to get that oil back down to the sump? Every head I install I polish the crap out of the oil passages and often Glyptol the surfaces. I suppose the best option is a dry sump system, but that's just out of my budget.

 

[Carb Doc]

If you have improved the flow back from the heads the next big restriction is the valley of the block, you can open the rear passages on each side of the distributor drive end of the valley, these can be opened quite a bit, polishing or paint will help as well. Unless you have a small capacity pan, you should not have a problem. I cant see where you would have a problem unless you are running extended periods at Very High RPM, then you could pump the pan dry. Don't forget, in a Chevy the Lifters are oiled by splash and drain back, DON'T plug the drain back holes along the valley floor.

 

[redvetracr]

http://www.moroso.com/catalog/categorydisplay.asp?catcode=13020

 

[clutchdust]

I've thought about those plugs and may still do it since I'm running a hydraulic roller. My thinking is that as long as pretty much everything on the top of the motor (lifters, rockers) is all roller, the only real reason to have any oil up on the top end is just for cooling. Of course, I don't mean bone dry, but a fine oil mist would be plenty of lubrication for lifters and rockers. But like Carb Doc stated, cooling the springs are really where the oil comes into play. And even at that, you only really need to cool the exhaust side. Too bad you can't be that selective on where the oil goes.
I'm pretty comfortable with what I've done on the short block. The front and rear galley holes were deburred and all the exposed casting of the block was Glyptol'd so I don't think there's a great deal of improvement to be had there.
I wouldn't be so hung up on pumping that much oil to the top if I feel more comfortable about the return. As it is now, I had to put baffles in my rocker covers to prevent so much of the oil from blowing out the breathers. The baffles have pretty much solved the problem, but I know there's still a bunch of oil floating up in the top of the block.
I don't suppose it's really as big a deal as I'm making it out to be. I've never had a low oil pressure situation but I would feel much more comfortable if there was a way to know how much oil was actually in the sump at any given time. As to what Doc said earlier, I would rather replace springs than crankshafts and rods.

 

[redvetracr]

But like Carb Doc stated, cooling the springs are really where the oil comes into play. And even at that, you only really need to cool the exhaust side. Too bad you can't be that selective on where the oil goes.
.

have you never seen valve covers with spring oilers? mine have small tubes with very small holes welded into them but the newer (trick) oilers use the valve cover sealing rail, you would also need a pressure source (mine is a dry sump pressure line) but they are the norm in most anything lasting longer than a drag race.

 

[Carb Doc]

The springs get hot due to the cycling action of the spring. the intake spring is likely just as heat soaked as the exhaust due to greater load, bigger heavier valve on the intake, if your springs have flat dampers between the coils this adds a fair amount of friction which compounds the problem.