The Stovebolt Site Forums The Shop Area Engine Shop High volume oil pump for 216/235?

Here's my latest off-the-wall project. Lots of stovebolters complain about low oil pressure, particularly on 216 engines with a little mileage on them. Now, I'm aware that I might be opening a can of worms where some of our obsessive/compulsive theoretical lecturers are concerned, but I'm looking at things from over half a century of real-world experience, not some pipe dream with no hands-on proof. Oil pressure is simply a function of supplying a greater volume of oil than is being leaked away by bearing clearance. If a pump delivers more oil than the bearings, shafts, etc. are leaking back into the oil pan, pressure rises. It would be possible to lubricate an engine adequately with zero oil pressure, as long as every bearing is receiving precisely the amount of oil it needs. One drop in- - -one drop out- - - -zero oil pressure!

A small block V8 oil pump has pump gears the same diameter, but almost 1/4" longer than a stovebolt 6 pump. The pivot shafts are a different diameter and length, but I believe that problem can be addressed with a little custom machining. By fabricating a spacer plate between the pump housing and the end plate, and doing some tinkering with shaft sizes, I believe it's possible to fit a set of small block V8 pump gears to a stovebolt pump housing. Longer gears = more volume, and more volume = better oil pressure, particularly with somewhat worn bearings and other pressure leaks. High-volume oil pumps were never manufactured for Chevy inline sixes, as far as I'm aware. I've heard that some people use a GMC oil pump on a stovebolt engine for better oil pressure- - -is anyone familiar with how that's done?

Stay tuned for more details as the project progresses!
Jerry

(Testing my own elementary understanding of the 216 oiling system)

I see where you're going as it relates to the pressurized components. More starting pressure at the mains, etc. ought to make up for some pressure loss due to excess clearance.

However, would a higher pressure pump change the situation in any meaningful way at the connecting rods? Do the 216 Rod dippers get somewhat oil starved from the supplying sprayer if the mains are worn and leaking pressure?

Back in the day, you could get an aftermarket kit that would do exactly that to a corvair oil pump. Spacer plate and taller gears that may have come from a chevy V8. Same shaft size, however.

Thanks, Jerry

This will be interesting.

Sounds promising, keep us updated please

JW, the splash/squirt oiling on the 216 is definitely affected by increased oil flow to worn main bearings. Anytime one part of a system demands more volume, the rest of the system starves, at least to some extent. I'm not necessarily looking for more pressure, just somewhere in the neighborhood of a 20% or slightly more increase in volume capacity of the pump due to the taller gears (more displacement). Even with the standard pressure relief valve in the pump cover, more oil will be available to the system, meaning there will be less pressure loss due to wear, temperature, etc. If someone wanted to install a slightly stiffer relief spring, then the pump will have an increased pressure capability as well as improved volume.
Jerry

The oil pressure is not really controlled by the relief valve in the pump in a 216. The pump relief valve is set at 75 lbs to prevent drive gear failure(with very cold oil, I suspect). The actual 14 psi max pressure is controlled by the oil distributor on the side of the block.
Here is a link to the Chevrolet Service News that explains this, and warns against increasing pressure.

Thanks Dave! That is exactly what we have been looking for! Chevy's actual word on the issue is worth anybody else's conjecture!

Upon reading Dave's link, it appears to me that the oil distributor dictates the balance of oil pressure between the rear main bearings/connecting rod bearings, and the remaining main bearings/cam bearings, to ensure that neither are deprived of adequate oil pressure.
I would suspect that if one were to install an oil pump with increased volume/pressure, that the oil distributor spring would also need to modified to open at a higher oil pressure (a stronger spring I am guessing).
What say you?
Carl

That article contradicts itself in the first few sentences. I'll build up one pump with the bigger gears and see what happens on a volume test compared to a stock pump.
Jerry

Can one increase volume output without a corresponding increase in pressure? (Temp and pipe dimensions being constant).

Been a long time since I had a physics class. I might be getting ideal gas law mixed up with fluid stuff.

Edit:

Found my own answer. Melling video

I understand better now what Jerry is after (flow not pressure), and it would seem the service bulletin wouldn't stand in the way.

Regarding that bulletin:
" Oil flows from the oil pump to a fitting on the cylinder block, thence to the rifle drilled passage to feed the main and camshaft bearings and also to the oil distributor. The pipe which leads to the rocker arms and the pipe which leads to the oil pressure gauge are tapped into the rifle drilled passage.
Oil, therefore, is fed to the main bearings, rocker arms and the oil pressure gauge before the oil distributor valve opens"

So why don't they run it through the filter FIRST???
They'll NEVER get a steady 30psi doing it that way, it's going to show fluctuations at the gauge as the RPM's raise and fall isn't it?

The 216 is regulated by the oil distributor on the side of the engine block to 14psi. (nothing to do with the pump). Maybe you are referring to the 261 full flow system? That is 30 and the stock filtration system has the oil filter placed just after the pump? The Spec has the rpm raise and lower number at 1650 rpm. In other words, the relief valve operates after that to regulate the pressure. If the engine is tight, that number is much lower.

No point in trying to educate a true believer. I'll have some real world measurements soon.
Jerry

the GMC oil pump bolts right in, it has the same mounting arrangement. You may have to fab up your own suction line, and/or discharge tubing from the pump to the block, but other than that it should be a direct replacement. There are also at least 2 different styles of pumps used in the GMC's, but either should fit. This was apparently the hot set up back in the day.

Even with some custom machining, I believe installing the readily-available V8 pump gears will be less expensive than trying to find the relatively scarce GMC pump. The modified pump should provide about a 20% increase in output volume compared to the standard pump. That should counteract the effect of increased main and cam bearing clearances on a well-used engine without going to the effort of a full overhaul. The concerns about "seal leakage" are just silly- - - -none of the seals have direct oil pressure applied to them and it would take a massive amount of splash to create any sort of a leak from a seal that was not worn out already.

The "14 PSI" quote for the oil distributor is the MINIMUM pressure required to get oil flowing to the squirter tubes for the rods, not some magical maximum that will cause an outbreak of Bubonic Plague if it's exceeded! That is to assure the other bearings get oiled on startup, before oil begins to flow to the rods. "75 PSI" pump relief valve?- - - -I wasn't born yesterday!
Jerry

No one has to believe me, or you Jerry, or Chevrolet for that matter...

It's okay to not know everything. The 216 is a 14 pound pressure engine as evidenced here:

http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0648.htm

All of the babbit splashers I have ever seen are 14psi at 2000rpm. The Oil Distributor is what controls that as well as the small tubes and orifices. Since the oil pumps pressure relief valve doesn't play into it, Chevy could use whatever they want I suppose.

In the later model years post 1955, the 235 was measured at 1650 RPM (30psi) so that explains why some of us here think that the oil gauge builds up slowly and goes up and down with rpm. (Full pressure engines behave differently because there is no oil distributor, the oil pump controls the pressure directly.)

I am awaiting this real world information. I am known for doing testing and providing real world information, so you can see where I would be all ears. You will have to overcome the deficit of starting off thinking Chevy's actual manual has it wrong, but I will be as pleased as everyone else if your testing gives us new insight.

Based on recent history, the subtle insults back and forth will get the topic locked before the prototype is even built.

Can we just all cool out until that's done?

I think it's an interesting project...regardless of which "side" the results vindicate.

Some GMC pump is still available from Melling as M23A, but it's about $200.

I have a '51 235 with hydraulic lifters, much the same as a 216 splash oiling system. It has been said that the oil distributor "controls" the oil pressure. If this is true, then why does mine see 30 psi oil pressure on a cold start on a cool morning? It has also been stated that the "oil pump controls the pressure directly," on full pressure systems. This is incorrect. Pumps create flow, not pressure. Hotrod's description of the the oil distributor function is correct

I have a 216 apart right now, please publish your results, this sounds like good idea

Got some steel on order- - - -update soon. Any company that managed to market the Corvair and the Vega could use a little help, I believe!
Jerry

I will assume that is not a shot at one of my "stovebolts". Sounds like a great project and interested in how it works out.

Sadly, I've owned both

Good project Jerry. The oil pressure got so low on the 4 cyl Continental OHV engine in my old 48 Ferguson TE20 that I replaced the oil pump hoping for at least alittle increase and got a whole lot more.
If a stock pump made such a big difference a pump with increased volume should be definitely improve oil pressure.

Dave

Gentlemen, I can tell you the oil pumps on all the Chevs are more than adequate. Fact is, they're actually too big on most every engine I've ever seen. Mains need very little pressure. Rods need the flow to keep them cool. 3# idling warm and 14# on hiway warm is correct on the dipper Chevs. Idling, the rods dip in troughs. As rpms build, the oil stream arc increases providing 10 times the oil pressure you see on the gauge !! As a professional builder of these engines for more than 6 decades, I'd never replace an oil pump, unless damaged. And certainly not with something bigger. I blueprint rebuild pumps.

Agree!
And if your pressure is low, pull some shims out of the mains.

I have no idea why oil pressure discussions are so passionate and bring the idiot out in everyone, but guys, I have a friend who stated it very clearly..

"While some of you are all educated in this and find these discussions to be Pedantic (as in fussy, not as in the real definition), there are some of us who are on the edge of our seats DESPERATELY trying to learn the things some of you just take for granted."

That is why I am here. Because there is hope for this group that maybe we can accommodate everyone at every stage in the learning process. We need to realize that every day, new Bolters are born and the same questions WE had a generation or two ago, are VALIDLY being asked today. Now that Modernity has advanced to where we are, we are asking questions in a different way, more basic, yet with the desire to take things a step further than ever before. How about lets LEARN together without letting the Dumass that resides in all of us derail the entire process!

I fight this phenomena every single time I post here, and frankly I am losing my sense of humor. How about let's be patient, POLITE, and put Human Decency and Kindness as the first thought in our minds as opposed to acting like a bunch of dumass Hillbillies straight out of the movie Deliverance! And, I digress thus we have come full circle!

ANYONE with any brains who has been here more than 4 minutes 59 seconds, knows that there are TWO people who put themselves forth as experts on these particular engines.

Pre68Dave is one of my best friends. He spends a lot of time here making sure the newbies questions are answered with respect and dignity. His father, who recently passed was very instrumental in teaching him this craft since he was a young boy. If ANYONE knows every square inch of the engines that are part of the stock experience, it's Dave.

HotRodLincoln is a presence here who has shown time after time his expertise as well. Although we do not get along, primarily because he does not understand the utmost and foremost importance of being kind and decent to his fellow man, his expertise is apparent and appreciated if you can wallow through the mud he creates by being a total [censored]. The idea of attracting more bees with honey does not even occur to him. I have spent my due time in the Military and have met him 1000 times over. I appreciate him as a result of my experience, but wish for the sake of the newbies he would have more tact.

As far as relating to THIS thread? HRL will do what he always does and not do anything. He created all this hoopla thinking the Oil Pump relief valve governs the 216's pressure. Once he learned it was the Oil Distributor, he will now completely back off and it's highly unlikely you will get anything worthwhile out of him. It's his way. He can't admit when he is wrong, so he doesn't say anything. Reference: The O2 sensor thread.

Jerry, I would love for you to take something and run with it to improve our engines. With all that you know, ALL of your life experiences, YOU of all people could explain Oil Pressure, and engines so that the newbies (and me) can understand. Yet you take the combative role instead. I do NOT understand. If Chevy thought at the time when they started in the 30's and ran through to the 50's the same engine, that 14 psi was insufficient, I would think that aftermarket vendors all over would have jumped right on that. That said, I applaud you if you efforts aren't just a bunch of bluster, and I hope something positive comes out of this.

And THAT is as good as you get from me. But let's all just try and get along. People, Staff, EVERYONE: Try to not let the dumass get the best of you. I will also pledge to do my very best to understand you.

Merry Christmas everyone!

Deve, if you want to lecture me, at least have the decency to do it by PM- - - -I'm sure the rest of the forum is just as uninterested as I am in your opinions. As for the rest of the so-called experts who have expressed an opinion, at least they have been relatively polite about it. You could learn a lot from the example they have set.
Jerry

As usual. So lets see if he puts his money where his mouth is.. Do not hold your breath!

As rpms build, the oil stream arc increases providing 10 times the oil pressure you see on the gauge

How does this occur?

C'mon boys, sounds like a worthy effort. Jerry's not known for tilting at windmills. Do the 216's have a reputation for failures due to low oil pressure?

I feel sure that most 216's failed as a result of the heavy cast iron pistons. At the time they were built highway speeds were not what they are today. This higher RPM's wreak havoc on the rod bearings.
In my experience, if rebuilt with aluminum pistons the bottom end problems go away.

Thanks Dave, that sounds like an fairly easy solution to these guys that want to keep the engine exterior all original. Now I see that you are also the Chev 235 guy (from your blog link). Should have known someone with that depth of understanding was hanging around the bolt. I'm just catching up with some of you guys that have been around a while.

Hmmm- - - -what are the most common complaints we hear about stovebolt engines? Limited oil flow to the rocker arms on both 216 and 235 engine, and low indicated oil pressure and lower end noises from the 216's, right? In an ideal world, everybody would just rebuild those engines back to original tolerances, buy a set of expensive aftermarket pistons, and drive happily ever after. Or, how about bolting in an oil pump capable of moving approximately 20% more oil at any given RPM, with no other modifications required, and using a set of off-the shelf pump gears to boot? A brand new small block V8 oil pump to scavenge some gears from can be had for a little over $20.00 with free shipping, and the rest of the bits and pieces for the conversion can be made by any machinist with more than three brain cells to rub together. I'll probably supply the blueprints for those parts for free to anyone interested. (Or maybe I could offer to modify someone's pump or sell them a kit for an outrageously high fee?) The fact that it looks like it can be done for approximately 10% of the cost of a complete overhaul might be a consideration also. If there happens to be a few shims left in the rods or mains, go ahead and adjust some clearances while you've got the oil pan off.

That's my plan- - - - if anybody doesn't approve of it, in the spirit of Christmas, please take note of the sprig of mistletoe attached to my coat tails!
Jerry

Gentlemen,
I'm new here and try to be helpful sharing info that's factual before I'm gone. Obviously, anyone can alter eng components as they experiment. It's their choice. My concern is newcomers will listen to simplistic fixes touted for a problem that doesn't exist. My advice is to thoroughly research original eng designs, respecting those engineers, prior to making changes. I should hope the purpose of this site is to educate, help people make thoughtful, sensible, economical choices which can make the hobby more enjoyable.
Mr Panic, The conrod w/ dipper direction of rotation is against the oil stream. A rod doesn't need much oil idling As rpm increases the dipper dives into the stream w/ more force. Plus the volume increases due to more crank degrees of supply. I've seen dippers ripped right off the rod due to that force. Maybe I haven't clearly expressed this. Ask again, I'll try again. Yrs ago this 10 times pressure was proved at Chev. Think about diving into a good size seashore wave. Incidentally, oil pressure is linear. Some very rare,expensive engs full pressure types I build only call for 5 (five) lbs idling.

An old discussion from the HAMB

Considering what has been posted in this thread, that looks like a more confusing discussion on the HAMB?

Mixing comparisons of higher-volume/performance oil pumps used on lower pressure 216/235 and on higher pressure 235s and 261s.

Mixing oil pump pumping volume and oil pressure at the bearings (on lower pressure oil system engines and higher pressure oil system engines).

Confusing....yes. But some interesting tidbits in that discussion as well.

Yes, the HAMB write-up is interesting/informative.

Oddly (from what I have sometimes seen on the HAMB), it is more friendly and less offensive/argumentative than some of the discussion here.

Thanks for posting it.