Technical What is too much oil to the top end?

I ask this question generally since I admittedly don't quite understand it all conceptually; what is too much oil to the top end of the engine?

Obviously different engines have different operating pressures and whatnot. But provided that there is sufficient drain back, and provided the oiling of the top end doesn't starve any other areas of oil, can there be too much oil to the rockers?

The thread on the Y block got me thinking about the topic. We're all familiar with engines like the SBC that oil the rockers through the lifters via hollow pushrods. It brings a lot of oil up the rockers, and oils not only the tip of the rocker where it meets the pushrod, but also the fulcrum as well. On the other end of the spectrum, it seems like you have the Olds Rocket and Ford Y Block, where you could stand-in a white dress shirt with confidence next to a running engine with no valve covers. I've heard folks say that you can flood the top of an engine with oil, but provided you have enough pressure and drain back, that seems somewhat counter to what I've always understood to be the case, where a steady supply of clean oil promotes lubricity and reduces heat and wear.

I've always understood that the oil pump will pump oil at a given volume until it reaches a certain pressure, at which point it will bypass to bleed off the excess. Could a higher volume pump compensate for additional rocker oiling? And will a roller rocker require less oil than a standard bushed rocker?

 

B/RB and LA oil through the pushrods ?
The late Magnum small blocks use the pushrods maybe,,,,but not the earlier engines .

Tommy

 

You know it's too much is when you run out of oil in the bottom end. You know it's too little when the rockers etc. wear excessively. Somewhere in between is the sweet spot.

Also, it's pretty common on modern race engines to squirt oil on the valve springs to help keep them cool.

 

It's been a while since I've had my valve covers off my 383, but I recall hollow pushrods with a small hole in the dimple in the rockers so the oil could flow back around the shaft

 

Nope .
383 uses solid pushrods and oil through the decks to the shafts .
Yes,,,,there is a hole in the rocker which allows a splash of oil to lube the pushrods tip .
Without it the pushrod seat in the rocker will burn up .
Look at a schematic of the old engines,,,,,it explains the factory oiling system very well .
Tommy

 

Indeed, I stand corrected. I'll edit my original post to reflect that.

 

Sorry Joe,,,,wasn’t trying to correct anyone .

However,,,it does bring up a funny story from years ago .
I bought a 440 maybe 25 years ago or longer .
It had been setting in a New Yorker for over 25 years at the time .
It had low mileage and was an excellent engine inside,,,,but I found the reason it had been parked all those years .
One of the rockers did not have the lube hole for the pushrod tip .
It finally burned through and the pushrod was sticking an inch or so through the top of the rocker.
I guess the punch had broken during the manufacturing process and that rocker escaped the inspection without a hole,,,,,LoL
It was a 68 440,,,,,and I still have it under my bench,,,,,with about 6 others .

Tommy

 

No worries bud, I certainly don't take it personally. The purpose of this thread is open a discussion on oiling, oil system modifications, etc., and I don't want to spread incorrect info unintentionally.

Your story highlights the very issue I'm discussing though. You need oil to the rocker bushing, as well as to the tip of the rocker. My Mopar has like 75 lbs of oil pressure and the valve train is soaked. I look at my 324 Olds, and there's basically no oil at all and seems to only need oil vapor to stay lubricated. Wouldn't it work better if there was an abundance of oil?

 

Yeah,,,,Mopar always had good oil flow to the top .
I agree,,,,,, some engines seem to have very little oil t9 the top,,,,,,and usually they suffer a great deal of wear .
I have read many times that it is a mistake to restrict oil flow to the top,,,,,oil also has a cooling effect on the springs as well,,,,,not just a lubricant .
And also the valve stems have to receive some lube,,,or they will stick .

Some racers might restrict the oil,,,,,but these engines only run a short period,,,,,and parts wear is not a big deal because those guys replace the valves and springs every year .

in a street engine,,,,I think it is a mistake,,,,use all the lube you can .

Tommy

 

The Mopars, big blocks and La, oil though the rocker shafts the exception is the magnums.

 

When we ran the big block Mopars on the dirt track, we restricted the oil flow to the rockers. We tapped the oil port in the block and inserted a carb jet into it, but I can't remember what jet we used. The motor sustained high RPM for long duration (our main event was normally 25 laps and up to 50 laps for special events, on a 1/2 mile track). The high rpm would reduce the amount of oil in the pan to a dangerous level towards the end of the main (lessons learned the hard way). Those motors didn't spend a lot of time idling though. Gene

 

For comparison, the straight eight Buick top end is lubed through a restricted [ .060? ] orfice in the front right corner of the head. Oil goes into the rocker arm shaft, then to the rocker arm , with a hole on top to oil the valve/rocker arm, an internal hole to oil the pushrod which supplies the hydraulic lifter. All 16 of them. Through that small orfice. Oil pressure is 35 lb.

Ben

 

Our Dart SHP uses T&D shaft rocker and has a solid lifter cam by race track rules. It doesn’t have near the oil up top that the hydraulic stocker does with stock style ball rockers. Like the typical circle track engine a 20-25 lap race with out a yellow flag is scary but we’ve never had low oil pressure and would not use a high volume pump. I know of a few LSR big blocks that have installed -12 lines on the rear of the valve covers down to the pan for extra drainage to save engines in a 5 mile pass.

 

My 427FE centre (Top oiler) has restrictors in the heads to limit the oil flow to the top end, however Ford revised the oiling system with the later 427FE (Side oilers) whereby the crank was oiled first and not the top end. Ford added an oil gallery passage along the left hand lower side of the block above the skirt allowing oil to be directed to the crank first, and then the cam and valve train. This is why they're known as side-oilers.

 

I guess it's different between race engines and high mileage stock motors.
The latter suffered two main problems, one being umbrella seals that broke apart and partially clogged the drain back holes in the heads.
On the Cadillac engines (at least on my 429) the oil was fed through an enlarged hole around a head / rocker shaft bolt. This hole was almost completely clogged with clay like sediment (same as was in sump) resulting in very poor oiling to the valve train and therefore excessive wear on valve tips.
On overhaul or a rebuild, the drain back passages would certainly be cleared and ideally smoothed out a little with a round file, and the oil passage cleared as well. So lots more oil could feed the valve train, and could immediately drain back as well.
Multi viscosity oils would help prevent thick oil from accumulating under the valve covers when cold.

I can't see any problem with large volumes of oil going to the valve train if oil pressure is maintained and it can drain back fast enough to avoid oil starvation. This should not be a problem in a more or less stock engine.

Interestingly on my 429 Cadillac after I cleaned up the passages the oil pressure light took a second or so more to go out, no doubt because oil now was also feeding the valve train.

 

With the rocker shaft oil feeds being timed through small holes in the cam bearings (#2 & #4 I believe) early olds rockets get very little oil to the top end.
I installed one hollow push rod with oil holes on each bank of my recently rebuilt 324 (running hydraulic lifters)
This provides significantly more oil to the valve train w/o starving the bottom end.


Sent from my iPhone using H.A.M.B.

 

^^^I did the same but one at each end of the valve train (2 on each side) and no issues as well.

 

This seems to be the path of least resistance in terms of getting more oil up to the rockers on the Olds Rockets. Just thinking out loud, while this method seems very effective to bring oil up to the area around the rockers, springs, etc. (basically all the stuff under the valve covers), it would seem like it ignores the largest wear point, that rocker bushing where it rides on the shaft. You're right about the timed oiling, but what if you bypassed the timed oiling? Put standard cam bearings in at #2 and #4 and block off the rocker oiling passage, and run an auxiliary line to a pressurized oil source T-ed off to go directly to the rocker shafts. I was brainstorming on that idea the other day, though it could be totally off base. Maybe it wouldn't work, maybe it's the long-cut to achieve the same results as the 4 hollow pushrods.

 

I think you're right.

But in terms of race engines and sustained high-RPM operation, while surely a circle track scenario would qualify as one, what about basic, non-overdrive, highway runs of 3000-3300 rpm? Is that enough sustained RPM to deplete the pan?

I agree with you wholeheartedly though, that ultimately a clean engine with modern oils is likely the best preventative measures one can take to keep the top end oiled.

 

Too much oil on the valve guides can result in oil burning. I would stick with the manufacturer's method and make sure it is working correctly. If you put a jet or restriction in the feed, consider using an oversize jet with a cotter pin thru it so it can't get clogged with sludge.

 

I had a 28 chevy for a little while...it had a piece of felt in the valve cover, you'd pull the cover off and squirt some oil on the felt every 100 miles.

It's surprising how little oil older engines need up top.

 

Some engine designs were more prone to problems, the Y-Block was definitely one of them. Contributing factors were "non detergent" motor oils of the day and/or less than adequate preventive maintenance. High mileage loaded up filters & sludgy oil, frequent short trips, and engines with thermostats removed and therefore running cold. Some oil types were more prone to paraffin buildup, aka "wax".

 

My first car ( I'm old) was a 40 chevy sedan with a clattering valve train that needed a squirt of oil nearly every day until I found this wonderous thing in the Honest Charley catalog consisting of a felt pad that laid on the top of the rockers. All that was necessary was to soak the pad in engine oil, remove the cover and you were good to go for at least a week before the rockers started to clatter again. Ralphie Squirrel types faster than me, sounds like the same product.

 

On the two straight 8's I have I've opened up that orifice a bit, to right around 0.10 or so. Never had a rocker cover flooding issue as there are plenty of pushrod holes for the oil to fall back into. I'm one of those folks that likes to see a good oil supply up to the valvetrain.

 

Yunick's Power Secrets book from the 80's has a good deal of info on restricting the oil supply to the heads when using roller rockers. SBC Nascar engine. I also thought oil to cool the springs, apparently very little was enough?

 

GMC 228-302 and some or all full pressure 235 Chevies also had a .060 restriction for the rockers

 

It is an odd thing, I’ve had to use cut out VCs on some SBCs when adjusting the lifters, others didn’t make any mess. As far I I know they all ran many a mile without issues.
I guess the correct answer is enough oil to keep things lubed.
Doesn’t answer your question, but has always made me wonder why some would give you an oil bath, others wouldn’t.

 

Smokey Yunick was an automotive genius.
But,,,,remember,,,,that was a SBC NASCAR engine,,,,,they needed oil for the bottom end .
The top end parts are expendable after a 500 mile race .
There is no telling how much knowledge went with Smokey to the grave .

Tommy

 

I read the Power Secrets book years ago. Smokey really was a genius.

 

Great thread guys !