For those of you that don’t know, I have been chasing a low oil pressure for about a year now. It runs about 35 lbs when I first start it to below 5 lbs. at idle when It heats up. I had the opportunity to speak to the gentleman that had the engine rebuilt about six years ago and he told me that it destroyed a main bearing right after he got it back from the machine shop. They told him that the clearances were a little too tight so they added a thousand shim. Since then he also experienced low oil pressure. The engine since the rebuild does not have 100 miles on it.
I finally pulled the engine and here is what I found under the main bearing caps. The first shim under the rear main is not .001” thick but .009”.
I was anticipating having to pull out a small shim but when I encountered the .009” shim that has me perplexed. I would seem to me if they needed a little more, why would they put a .009” shim in? At this point, I believe I have to pull the crank and get proper mic readings. That way it will tell me if the bores are out of round from the shim and what the actual clearances are.
Can I pull the crank without pulling the pistons? I have not pulled the head as of yet trying to cut down on the amount of work but now I’m thinking I may have to.
It also brings up another question. If the shim raises the bearing cap by .009”, does it also separate the bearing shells by the same? Wouldn’t that create a leak path?
The other issue I encountered was the area where the rear main seal rides on the crank is pitted. Do they make a SS sleeve to fix that?
Well, a couple of things. First, yes there is a speedi-sleeve that will fit the crank end. Jerry knows the part number and I'm certain he'll comment on your question. It will allow you to use the neoprene seal (which in this year engine ought to be a better answer for you by a long shot). Next...whoever it was that did the work on this engine should be avoided. Something went plenty wrong here. Take a look at the first image you attached. The bearing in there is worn more oddly than I believe I've ever seen. Unless there's a terrific optical illusion going on, it tapers from rear of engine to front by what appears to be about 2mm and it seems to sit up in the back off of the cap. That (unless this is a weird illusion) is a very serious mistake. You can pull the crank without pulling the pistons. Get 12 pieces of thin rubber tubing cut about 1.5 inches long that will fit over the rod bolts (so you don't nick the crank in the process), remove nuts and rod caps and push them up and out of the way. But either way you need to get that crank out and to a machine shop where the people don't drink all day. I think you need to have it checked for size and reground and install new main bearings. You also need to check the rod bearings. What is going on with that bearing we can see I could only guess, but that isn't good. No shims should be used on new bearings. What you need is to have the crank ground so that the gap between the crank and bearings will be .001". At the most, I'd say .0015" but lean on the machinist to get it to .001" and your oil pressure problem should be greatly improved. Of course we don't know what they did with the cam bearings, but hopefully not what they did with the lower end. As for your question of the .009" shim, the answer is that is wrong from every possible angle. And we don't know what they did to the bearing to make this fit together, but yes...it could create a problem oil path...not to mention other things. I doubt the main bearing bores will be out. Good luck and please keep us posted.
Wait a minute...the shim is causing that bearing to appear oddly worn. That is causing the illusion. At first I could not see detail in the scan and thought this was gasket sealer, but what I'm seeing is the shim they made. They cut this one to match the entire surface of the cap on the rear main (but only on one side or is that a shim piece over to the left side of the image?) whereas on the other cap (in the third image) they just stuck some shim stock under the cap? Yes, that will create an oil path...plus the approach is very odd, don't you think? In the time it took to make that shim, they probably could have ground the crank correctly.
The cap does have two shims. They appear to be pre-cut and not home made. The second shim is in the first picture on the table to the left. Thanks Jon for the tip on pulling the crank. It will be a couple of days before I get back to it as it’s my grandson’s birthday.
Look’s like I need a recommendation for a machine shop near Albany NY.
Thanks Phil, your grandson's birthday is more important. Hope somebody here will know of a good machine shop up your way. I looked on Amazon and they still sell the rod bolt covers. Interesting. Used to you had to buy these in a pair and they were yellow. I have a pair which I've had since the 60s. https://www.amazon.com/Goodson-Rod-Bolt-Protectors-16/dp/B0009RH412
They put an entire shim pack between the block and the cap. If you examine those shims carefully, you'll find that they're composed of a stack of .0005" layers. If you use a box cutter blade or an X-acto knife you can peel them apart and adjust the clearance properly. Start by cutting a small bit of one corner away with tin snips, then use a sharp knife to peel the layers apart at the cut you just made. I prefer to set bearing clearance with a narrow piece of .0015" shim stock (about 1/4" wide) between the bearing and the crankshaft instead of Plastigauge. Start with no shims at all between the cap and the block, which will lock the crankshaft. Start adding shims between the cap and the block in .0005" steps until the crank can be turned with just a bit of effort by pulling on the flywheel. Don't forget to remove the checking shim! It's acceptable to make a 1-layer difference from side to side to fine-tune the clearance. Check ALL the main bearings the same way- - - -anyone who made a blunder like you've found already has probably made a bunch more errors!
Pulling a crankshaft with the engine in the vehicle is a huge pain in the derriere because the separator plate between the block and the timing cover keeps the crank snout from dropping more than a half inch or so. You'll have to remove a bunch of stuff, including the camshaft and the crankshaft timing gear to get that plate off. I'd prefer to pull the engine. 3/8" ID rubber fuel hose makes an excellent rod bolt cushion, and they sell it at every local parts store.
The 59 should not need shims at all. Shims were 55 and earlier motors that used the rope seal and a different style of bearings. Really there should be no reason to shim the bearings on a fresh 59 to get to proper clearance. Someone simply did not want to make the needed correction and decided that good enough was good enough. What a disgrace. So there are a couple of things you might consider here. First, if you are taking the motor apart, have the block check for main alignment. These motors are not known for having the mains out of alignment but every once in a while you come across one that is really out of wack. The thing is that aligning the mains on one of these motors is not like aligning the mains on a small block chevy in that the procedure for a 235 is more complicated then usual because each of the mains is a different size and requires setting up the cutting bar for each main. That and moving the clearances around can sometimes play havoc with the gear teeth clearance on the timing gears and the neoprene rear main seal will now also need modification. So check it and if its within a normal range, go with it because but you really don't want to go down that road if possible (expense and work wise).
As for the bearings, if you flip the bearing shell around you might be able to pick up a part number and that part number will tell you if the crank was ground undersized at some point. If so, you might consider getting the next size bearing and then get yourself to a good machine shop. The right way t do this is to install the bearings and tighten the main caps. Then you measure the id. Subtract whatever clearance you want, .001, .015, and that is the size you machine the crank to. Now you have some accuracy on the machine work. As you have determined, the wider clearances have a negative effect on oil pressure. A lot of race cars build that excessive clearance into their builds to reduce parasitic drag. But they change the standard volume pressure pumps to some more to take up the pressure bleeding off for the larger clearances. A 235 does not need that at all so I think if you can get the bearings and crank clearances sorted out, you will find a much better pressure situation going forward.
My line bore machine has spaces for several cutter bits. I set up four cutters to the appropriate diameters, and make all the cuts in one pass. The trick with timing gear tooth gullet clearance is to make only a .001" to .002" cut into the block and take most of the material out of the caps. Set up the boring bar exactly concentric with the bearing bores at both ends of the block, lower the bar slightly so the cutters just barely scratch the block, and machine .010" off the mating surface of the caps. When the cut is made, the holes end up round, in line, and the right diameter, and the bearing caps don't care if they're a little shorter.
Most people who pontificate about line boring have never actually done it.
Thanks for all of your advice. As soon as I can, I’ll pull the crank and mic up all of the clearances to see what I have and report my findings.
That is an interesting comment because I have not personally machined the main bore of a block as I am not a machinist. But, like most others, I have had to have a machinist do the work for me. And yes, and I have had to line bore a block (two of them actually, both 261s which is why I went to the trouble and expense) and the truth is that most machinists don't want to be bothered. Its just not that profitable for them and it takes a lot of set up time to get it right. I know exactly how much time it takes in that quite a few years ago now, I watched Jimmy Fox at the now long defunct K&G Machine Shop in Havertown PA (Mr. Fox was the Fox of Frantic Ford funny car fame) do the set up for one of my 261 blocks. Was probably around 88 or 89 or so. I am not even sure Mr. Fox is still living. What I can say is that he had great patience for my project. It was my first early style motor line bore and taught me a valuable lesson, the expense may not be worth it. If you are lucky enough to find a machinist who is willing to take on the job, its expensive. More expensive then just replacing the block when all is said and done. Can it be done, yes it can. Is it worth it, usually no. In my view, a 59 235 that is so out of line you need to re-bore the mains straight is financially more likely a candidate to just be replaced. That is my experience any how.
My hope is the block doesn’t need anything more than new bearing half’s and a crank re-grind. Gotta think positive!
Most engine machinists who allegedly learned their trade in the past 20 years or so have a habit of building up stovebolt engines with tolerances that are way too tight- - - -particularly rod and main bearing oil clearances and valve guides. What we used to call "normal" clearances on those engines is "worn out" on the rice rockets they're accustomed to working on.
Make sure that whatever you take apart gets marked so it goes back exactly where it came from, same orientation.
What exactly is the reason not to got to a newer 235 design? I keep forgetting why folks spend all this time and money and constant headache. I don't think I will ever understand the mental aspect of this decision. Just as there are very few to work on them, there are very few who know it's not a babbitt motor. It all looks pretty silly from my lofty position.
"Reading is Fundamental"- - - - - a 59 engine is a "newer 235 design". Makes no difference- - - -the main bearing dimensions are all the same on 216, 235, and 261 engines.
My comment was general about low pressure era and babbitt era motors. They seem to be more complex to get serviced/rebuilt. I will decline further comment. Two many toes here.
The reason for the spun main bearing from the previous owner could well be that the main bores are out of line. But another could be that somebody ordered the wrong part number for the mains or the late bearings weren't available. Perhaps not knowing that they require shims he just put it together tight. Then having spun the bearing he shimmed it's replacement and not being familiar with the shims installed the whole pack. If they shimmed all of them like that it would have set up a heck of a racket aside from low oil pressure.
What I'm working around to is that the crank and the block might be OK. Usually, if a bearing is spun the journal will be really ugly and will need to be reground. I've forgotten if the OP said the engine was in the truck or not. But as HRL said it's a royal pain to pull the crank with the engine in the rig. What I would do, being both cheap and lazy, is to pull the suspect main cap and another and see it they are both stamped with the same undersize. If so, assemble them with plastigage torque it down and see what you get. Shim if you need to get the proper clearance. Once you get it assembled with the proper clearance, with the rods tucked up inside, you can rotate the crank. You won't be able to spin with abandon but you'll get enough rotation to see if it spins free (have the rear main seal out). If it turns free then the crank is straight and the main bores are OK. If not, well, look for another block or line bore that one. But before you go to that expense have the machinist make darn sure the crank is straight.
The shims are a tricky deal. I sent a set back to the vendor because I couldn't figure out how or if once could peel them apart. I salvaged the old ones instead. I'm not sure what years need to be shimmed and what don't but if it's too tight I don't see anything wrong with using the factory shims for an earlier motor. You might loose a little crush on the bearing shells but so did the shimmed early ones. I see that the lower halves are pinned so the bearings aren't going to spin on account of too little crush. You shouldn't have to shim much, maybe 0.002 tops. If you would have to shim a lot then the bearings don't match the crank grind. Set the rear main up on the tight side (but not too tight) to reduce oil leakage from the seal.
Hope this wasn't too confusing.
People have gotten far too complacent about checking and/or adjusting oil clearance because the machining and quality control of modern engines and bearings has gotten so good. If it doesn't fit right by simply bolting stuff together it must be junk- - - - - -throw it away and start over with a different engine. Any sort of skill or thinking ability isn't required for parts swappers- - - - -real mechanics are a dying breed!
Phil, I lived in the Albany-Schenectady area years ago. A couple of my brothers-in-law still live in the area, so I checked in to compare notes on machine shops. One sort-of stands out in our collective opinions, XLR8 Machine Shop
], in Cohoes. I used it 35 years ago for a 454 build when it was "Noel's," but since then it has changed ownership, but maintains high standards, according to what I hear. Steve Stack is the current owner. He has a vintage Perkins head and a 409 posted on his FB page, so he has familiarity with some vintage iron. You may want to chat with him and ask specifically about stovebolts.
Hope this helps.
Dave Hunt's Auto Services, Inc.
They do modern and performance engines.
In 2014 they had an engine-man who knew the high-pressure 235 (he had rebuilt many).
They did a very nice job on my 1954 truck 235 (to be used with a Hydra-Matic transmission).
Thanks for the recommendations! I hit a snag disassembling. The bolts that bolt the oil pump accessible from out side the block, are offset in the recessed hole to the point I can’t get a socket on it. I’ve tried both 6 point and 12 point sockets including SnapOn. The recess measures 3/4” across so there is not much room to begin with. I know that I can drill the heads off and remove the remainder of the bolts when I get the oil pump out, but I figured I would ask the experts before I resort to such drastic measures.
Those aren't bolts, Phil. Those are more like rivets which hold in the oil pump mount. First remove both oil pump tubes. Then remove the single screw holding the pump into the mount and slide it out. Installation is reverse.
You might need to rotate the crank to gain access to that screw.
Thanks “Jon G”! That would have been a grave mistake. I’m so thankful that this forum exist just for these times I get stumped. Thanks again!
"Danger, Will Robinson!" That bracket was aligned with a special fixture at the factory when the engine was assembled, and although it's attached by dedicated headless shoulder bolts, it's never supposed to be removed, even during an engine rebuild. There's one bolt with a lock nut that has a tapered point that engages a hole n the side of the oil pump housing. That sets the proper height of the pump in relation to the distributor shaft when it's installed. The lock nut is tight, and extremely difficult to reach. A lot of guys who did stovebolt lower end work would heat and bend a long box end wrench to make sure they got a good bite on the nut for both disassembly and reassembly.
Another question. How does the timing gear on the crank come off?
Can the crank be removed without taking it off? It doesn’t appear the there’s enough room to get it thru the backing plate for the cover.
My Motor’s book says there are two tapped holes to be used with a plate style gear puller. They appear to be missing. I have a three jaw gear puller but there isn’t enough room to get the arms behind the gear.
You can either stand the engine up under a floor mount drill press and drill and tap a couple of holes in the gear, or grind the jaws of the 3-jaw puller down so they will slip behind the gear. The original equipment crank gear had two threaded holes to accommodate a puller. Lots of replacement gears don't have those holes. I have used a couple of heel-shaped pry bars to move the gear out far enough to get a 3-jaw behind the gear.https://www.amazon.com/Pcs-Heel-Pry-Bar-Set/dp/B000RGPYNA
All the front plates I've ever seen would come off without removing the gear, Phil.
All the front plates I've ever seen would come off without removing the gear, Phil.
I've seen a lot of crankshafts out of the engine with the timing gear still attached, so that's probably right. The 216 I just disassembled didn't have a front plate on it, but it didn't look like the gear had been removed and reinstalled. There are a couple of flat-head machine screws holding the plate to the front of the block that are a little difficult to see, particularly if part of the paper gasket for the timing cover is still there.
Note...there is a tube about 1 inch long protruding from that front plate. There is a hole in it and that hole should point toward where the cam gear and crank gear mesh. You want to be certain the tube is in place and positioned correctly. There are also 3 screws with large heads which may (should) be staked at one end of each slots. Depending on who did what, you may need to use a small hammer and screwdriver to push some metal out of the slot to make it easier to turn.
Thanks, I try removing the plate. I have a hand held impact with a large flat bladed tip. I’ll try that. Thanks for the tip!
I finally got the crank out. Before removing, I used PlastiGauge on the rod journals and they all had .0015” clearance, so I think they are OK. I also mic’d the main journals for clearances with the installed shims and they were way too big as expected. It’s no wonder why the oil pressure dropped off.
The measurements were taken at 12 o’clock to six showing the maximum clearance. I made a spreadsheet to show the clearances.
I’m not sure what to do at this point. As I see it, I could split the shims and attempt to get the clearance I need, taking the chance that the issue that caused the bearing to cease is still there, or take the block and crank to a reputable machine shop and have them solve the issue.
The last thing I want to happen, is to have to take this engine out again.
First, measure the crankshaft. Use a micrometer, NOT a caliper. Even a digital caliper isn't capable of making measurements as precise and consistent ad you need to make. Here's a list of the standard diameters of the main bearing journals:
Normal undersizes are .010", .020", and .030" For instance, a #4 main bearing journal that's 10 under would measure 2.7665-2.7675". Once you figure out the crank journal sizes, torque up the main caps with the bearings in them (no shims) and measure the ID of the bearings with an inside micrometer. Subtract the difference in the bearing ID and the crankshaft OD to get the oil clearance. Be sure the bearings ID is round and straight, not tapered or egg-shaped.
If the clearance is very far out of spec, have the crankshaft reground to the next undersize and buy the right bearings. Since the rods are OK, all you need to correct is the main bearings. That's four journals to regrind instead of 10.
If the clearance is only slightly too tight, some machine shops will polish the shaft using an electric powered belt sander with a long narrow belt specifically designed to surface crankshaft journals. Most shops don't like to take a journal down more than about .001" due to the possibility of getting the shaft out of round.
OK- - - -I just looked at your dimensions- - - -the crank is already .030" undersize-- - -not really a candidate for further regrinding- - - -BUT, there's still room, to grind a little on the rear main journal. It's .003" too big for a .030" undersize bearing. All a machine shop would need to do is grind and polish the rear journal to a proper .030" undersize dimension. That's too far to polish, but a cooperative machinist who knows his stuff can bring the rear journal into spec. and you can put a new set of 30 under mains in it and go back together.
The pitted seal surface is another problem. A 3 7/8" stainless steel speedy sleeve is available, but that will make the shaft too big for a rope seal. You might get by with using a 2-piece rubber seal, but the permanent fix would be to machine the back of the block for a Chicago Rawhide #38647 full circle lip seal. That will require tearing the engine down to a bare block, however. Good luck!
I'd suggest finding a STD./STD. crankshaft with a good seal surface and getting it reground to .010/.010. There's a salvage yard in Albert Lea Minnesota that does a lot of advertising of stovebolt parts on Ebay, including crankshafts, and their prices aren't outrageous.
My 235 in a 54 has 31.000 since a complete rebuild. at 60 + mph it is around 30 lbs but at idle 6 to 10. could it be the gauge or oil. Here in Florida I run 30 wt. Castrol. Doc.
In searching out my options, I found that you can buy .040” undersize main bearings. Is there any reason that I couldn’t use those and have the crank reground? Main Bearings
I re-measured the mains without the shims and confirmed that the rear main journal wasn’t ground sufficiently. I also measures the camshaft journals and they are all over the place also. Here are my measurements.
Because there's a bearing a particular size doesn't necessarily mean it's a good idea to grind a shaft to fit it. Back in the dark ages, a 30 under shaft was considered to be a shade tree fix, and virtually nobody but "no warranty" used car lots would ever grind a shaft smaller. I've seen some hack jobs with one oversize piston in a cylinder that had been scored, or a single rod bearing journal ground undersize by someone with a portable crankshaft grinder. On a 216, it was possible to swap connecting rods from the bottom on most cylinders. Pull the piston down far enough to expose the wrist pin, loosen the pinch bolt, and wiggle the wrist pin out one side! I'd probably choose to make your crankshaft a mailbox post if it were in my shop.
I've got a brand new Melling cam for a 235 that's never been installed in an engine. I'll post some journal diameters shortly.
I know a lot of folks will say no more then .030 but these 235 cranks are cast steel and Are pretty rugged. The reality is they can go as much as .060 and while I had a motor that I did take to .060, it would not be my first choice. In a pinch, yes, by choice, probably no. But .040 for a stock motor, I myself would do that with out thinking twice.
They're forged- - - -not cast, and they're so tough that they dull tungsten carbide lathe tools very rapidly. The stroker shaft I'm building is going to have a rod journal almost 1/2" undersize, but it's going to be a dyno test engine, and I won't be terribly disappointed if a journal that small doesn't work. I'm going from 2.312" to 1.850". Those rod bearings work on NASCAR engines at 9K+ RPM, though!
Jerry, I don’t think they are forged steel. Every machinist that has done work for me has characterized them as cast steel, not forged, and not cast iron. Now you have me doubting What I have always thought was the case. I think I will get in touch with tom Langdon. He will know for certain.
I've always been told they were forged, Mike. I've also been told 30 under was a good stopping point.
How many of them have you reground and/or machined, Mike? One cut with a grinding wheel or a tool bit will show anyone with proper experience the difference, and the lack of a narrow mold parting line is a dead giveaway it's not cast metal of any kind. Early camshafts are also forged steel, and I've had both items in my lathe in the past few weeks.
The 1936 Chevrolet film “His Masters Hands “ shows a great shot of them forging a crank at the factory.
Oh they could be. Dave, that is a great film, I just looked at it. I just accepted as true the cast steel description. And yes, I prefer no more then .030 but if it needed to go to .040 that still would not concern me on a low rpm stock motor. I have a .030 over crank in one of my motors that gets to 5600 rpm every once in a while and no issues, nor do I expect any. .040 on a motor that never sees more then 4000 rpm, I would be fine with that. Truth be told, I have a set of .060 bearings in my part stash and if I was in need of a motor right then And there, and could not find a replacement crank in time, I would go the .060. Not really under that kind of pressure to build a motor that quick but I keep The bearings nonetheless.
That is a neat historical film...I've watched it many times.
Did anyone else catch the front fenders being stamped are for the 1935 Masters and not the 1936's?
Does anybody know what clearances the cam bearings should have? I looked in a Motors book I have and could not find it. I also looked for it on the web with similar results. One of mine seems a bit excessive. #3 measures about .005” over the size of the cam.
Here's a reference:https://www.canadianmilitarypattern.com/1960%20235-261%20Engine%20Manual.htm
near the end on page 16-13 there's a table that says 1.5 to 3.5 thou.
Wow, I just checked out the film from Dave!
A fever dream of industrial assimilation, not the hands of men, just organic bits synchronized with a whirlwind of iron... amazing.
I bet there was high turnover due to lack of safety glasses, hearing protection, or respirators!
I would imagine that in the 1930's those people appreciated having a job- - - - -any job! My grandparents kept a lot of the people in their neighborhood in Nashville employed about the time that film was made, delivering coal and ice, building houses, delivering dynamite to mines in east Tennessee and Kentucky, and trucking beer to Nashville from Milwaukee and St. Louis.
I just dropped off the entire block to a recommended shop about an hour away from my house. They are going to check out all of the bearings and journals and get back to me within a week. They also said if the rest of the mains checked out they can grind the rear main down .003” to get it in spec, and go back with 30 over mains.
In the meantime, I have allot of cleaning to do.
I'm working on a way to fit an oil pump for a 250 inline six to a 216/235/261 engine with a little bit of fabrication. The higher volume of that pump will be able to compensate for wide bearing clearances the same way a race engine oil pump deals with bearing clearances approximately twice what a street engine runs without losing oil pressure. As long as the oil gets to the bearings faster than it leaks away, getting anal-retentive about clearance isn't necessary. It's still a good idea to keep the rear main bearing as tight as is practical to minimize seal seepage, but machining the block for a full circle lip seal will handle that little problem!
I just picked up my block from the machine shop. They hot tanked the block, reground the crank mains, the rod journals and reground the cam journals, honed the cylinder walls and installed new rings. They also ground the rear main seal area on the crank and installed a new two piece neoprene seal. I decided to have them assemble the block so it would make it easier for me to finish the rebuild.
They also found that when the engine was previously rebuilt, the shop never properly cleaned the block so all of the passages and cavities were filthy. Some of the grit found its way back into the oil and scored most of the bearings.
They asked me to bring down the head as there was evidence that two of the exhaust valves had made contact with the pistons. While I picked up the block they popped out the suspected valves and found no damage. They also did a leak down test and a few of the valves were leaking. I left the head so they could clean and magnaflux it and go thru it. It makes no sense in doing all of that work to the block and not insuring the head is good.
Once the head is done, I’ll basically will have a new engine. Hopefully they don’t find any other issues! Got my fingers crossed!
Looks/sounds good, Phil
Let us know how this works-out/ends-up.
Unfortunately, a dirty buildup is a pretty common problem, and it has ruined many a new engine. I always pull all the oil gallery plugs and run a solvent-soaked rifle brush through all the passages, followed by a thorough pressure wash. There's no such thing as a "too clean" engine assembly!
How do stovebolt exhaust valves get close enough to touch the pistons? The intakes are the ones that are pointed straight down.
How do stovebolt exhaust valves get close enough to touch the pistons? The intakes are the ones that are pointed straight down.
I can’t answer that. I did see the moon shaped dents on two of the piston tops before they shrink wrapped it. In a day or two, when I unwrap it, I post some pictures.
Oil pressure on 235's are notorious for reading low oil pressure. I'm sure that Hotrod Lincoln can give us some stats. Doc.
The solution to low oil pressure on a late model 235 is a Melling M-45 oil pump. The one we put on John's 261 was holding 30 PSI at hot idle. Of course, that was a brand new engine with minimum clearances on all the bearings. At cruise speed, the pressure was considerably higher. The stovebolts with chronically low oil pressure are the spray-oilers, 216's and early 235 which have too-small oil pump gears. If things work out as planned, the retro-fit of a pump for a 250 to a 216 should almost double the volume of oil leaving the pump. That should allow 216 owners to see something other than zero pressure at idle once the engine warms up! It should be a fairly simple conversion, with just a little tweaking of the plumbing for the pickup and the pressure line to the block.