1947 Flathead Oil Pressure

[Jeff Trahan]

I started my rebuilt engine briefly (a few seconds) and I'm concerned that I'm not getting oil pressure.  With a rebuilt oil pressure gauge installed, there was maybe a slight blip when the engine first started then zero pressure indicated for a few seconds until I turned the engine off.  Several weeks ago, I pre-oiled the engine with a Melling pre-oiler through the oil pressure port, then cranked it over for several seconds with no spark just to make sure the starter was working.  I had forgotten to install the oil pressure line so oil flowed out of that port.  That made me think the oil pump was working (it was rebuilt) and that there would be plenty of oil pressure.  Oil also came out the port on the side of the block (near the filler tube) when I had that line disconnected.  During the restoration, I cleaned out the oil pressure line and blew it out with compressed air.  Does that line need to be filled with oil for the pressure reading to be correct?  In other words, if the line is mostly air, will the pressure reading be zero?  Thanks for the help.

Jeff Trahan

[Dave Shepherd]

Pre oil it again til you have pressure.

[Bobby B]

Jeff
Hi…Did you put the "restrictor" back in the oil feed port on the side of the block and could it possibly be clogged? Did you pre-oil it with the valley covers off to see if you had flow up to and through the lifter blocks? How do you know the gauge is correct and could there be a blockage in the line? The factory oil pressure line has such a tiny diameter and maybe there could be a blockage? I wouldn't chance starting it, but maybe go down to the local parts store and get a substitute cheap-o gauge with the plastic line and give that a shot first by cranking it over with no spark. Take the plugs out to ease the strain on the starter and your battery. I'm sure you rebuilt the pump? There's only one oil galley on the driver's side of the block, which I'm sure was cleaned out with some rifle brushes when the block was washed? Some engines pump up quickly and some take forever when dry.
                                                                                                                              Bob
,
 

[Jeff Trahan]

The first time, I pre-oiled it without removing the valley covers.  So this time, I removed the valley cover and there is no oil getting to the top of the engine even with about 100 psi on the pre-oiler tank through the oil pressure port. Then I disconnected the line at the port on the driver's side of the engine block and connected the pre-oiler there.  There was still no oil getting to the valve blocks.  Then I disconnected the small lines inside the valley area and saw a very slow drip of oil.  So even at about 100 PSI directly into the line that feeds that area, I'm getting very little oil.  It seems like it must be a blockage at the top of the engine because the line is new.  Any other ideas?  I thought when the engine was degreased it would have cleaned out all the oil galleries.

I've pre-oiled another engine (1955 Buick nailhead) by using a drill in the distributor hole but it looks like this engine can't be pre-oiled that way unless I remove both the distributor and the "tower" that goes between the distributor and the block.  Can anyone confirm that?

Thanks.

Jeff Trahan

[Bobby B]

Jeff,
   Hi. You're going to have to analyze this problem one stage at a time.  The oil not getting to the lifters is either not leaving the side port on the block, the steel line up to the lifters is clogged, or one of the brass fittings is clogged, and most likely the first one that the "main" feed comes into first. Every one of these fittings I've ever been into was almost closed off completely with hardened crud. I've sometimes wondered  how the engine even ran under these conditions. The oiling system in this block is very simple. It sounds to me like you either have a blockage or an open port somewhere bleeding the pressure off.  You can make an oiler out of an old distributor shaft if you needed to. Are you sure all the plugs in the block are closed off? I think someone here on the forum had an oil pressure problem and it was due to the crank plugs not being re-installed after cutting /cleaning. I have a few spare cranks here, so I could verify if that's a possibility. I know for a fact that these blocks are full of s*** when you break them down. They need to be cleaned out for hours upon hours, in-between the bores, the galleys, and scrubbed down. Before I send any block out, I will pressure steam clean it till it's spotless, pick away at all the hardened crud around the bores in the water jacket, go through all the ports and galleys with hot soapy water and brushes, and chase out every thread on the block. The machine shop will usually hot tank it, and thanks to the EPA, it does not do the same job as it used to do 20 years ago. Once the block comes back from being machined, I usually go through the whole cleaning process once again to make sure no swarf or particles were left behind which could easily destroy a brand new engine. Something's not right. Try and break each part down, because sooner or later you're going to find out what the issue is. Keep us posted and Good Luck!
                                                            Bobby

[Jeff Trahan]

An earlier post mentioned a "restrictor" in the oil feed port on the side of the block.  What is that?  I disconnected the old line that goes from that port to the top of the engine and installed a brand new one.  If I disconnect that line at the engine block port, oil flows freely from the port when I crank the engine.  Is there supposed to be a "restrictor" in that line?

[Bobby B]

Jeff,
  Hi. The restrictor is what maintains oil pressure to the lifters by funneling the oil through smaller orifice. Did the block have one before you took it apart? If it didn't, maybe they were running a remote filter which acted as a restriction in the line feeding your lifter blocks?
                                                                         Bobby

[Jeff Trahan]

Thank you for the photo.  The restrictor is installed in the port in the block and the stainless line connects to it.  So I guess I'm fine there.  We disconnected the lines in the valley and blew them out with compressed air.  Got some crud out of them and now oil flows to the lifters.  How much oil should be flowing through that area?  It didn't seem like there was a lot but I don't know how much is supposed to be there.  I guess as long as the oil pressure gauge has a normal reading, we should be OK.  Probably will be firing the engine up again tomorrow to see if we get pressure.  Should there be pressure with just cranking the engine or does it not register until after the engine starts?  Thanks.

Jeff

[Bobby B]

Jeff,
Hi. All the crud builds up in the fittings, so I would advise to take them out now and clean them out thoroughly before starting up the engine if they weren't already cleaned out when you had them apart. The crud is packed so tight in some of them, that I've had to use a trans pick and BrakeKlean to get it all out. From what you're telling me, I would get everything spotless before you start it up and encounter problems. The crud isn't going to go away on its own…..And yes, you should have pressure on the gauge when spinning the pump even when stationary. Keep us posted. Good Luck! 
                       Bob

[Jeff Trahan]

After cleaning out the fittings and lines in the engine valley, I started the engine and got about 25 lbs of oil pressure at idle and about thirty at 1000-1500 RPM.  I think that is the right amount.  There is a bit of lifter noise though.  It seems like it's coming from the right side of the engine.  I attached link to a video file.  Is that normal for an engine from that era?  Is there anything I can do to make it quiet?  Thanks.

https://www.facebook.com/video.php?v=322451634614347&l=3091751305355219707

Jeff

[Bobby B]

Jeff,
The pressure is about right which is really a factor of the bearing condition (assuming the oil pump is working properly), not the lifter blocks. That seems a little loud, but it's kinda' hard to tell from the video without being there……Is it only One side? Is is only ONE of the lifter blocks? The front blocks are fed from one "Y" feed and the rear blocks from another.  Did you also clean out the fittings that feed the blocks? Did you disassemble each lifter, in each block, clean them out, "rebuild" them, and put them back in the same block/hole they came out of? If you have all of the above covered, did you check the distance between the valve stem tip to cam heel? It should be EXACTLY 3"……VERY critical in this engine. The lifters will not compensate much if this figure is off, which could be part of your problem. Is the cam new/ used? Are they the lifters that were in the engine? I'm sure you already know that you basically can't install a new cam on old lifters unless you want to wipe the cam out immediately. If it's a used cam was it checked before re-installing? You have a lot of variables going on here. We need all the info, but I would say yes, it doesn't sound right……
                                                                                                              Bob
Check out this running motor @ 2.00 min.

https://www.youtube.com/watch?v=hd_51uAY_28

[Jeff Trahan]

I had the engine rebuilt by a local machine shop.  I don't know if they used the original lifters or if they kept track of them and put them back in the same spot.  I'm pretty sure the cam shaft is new.  When this engine was new in 1947, I doubt they worried about where the original lifters were placed and they weren't "matched" with the cam.  Why does it matter on a rebuild?  Sorry for all the questions.  I'm really new at this.  How will I know if the new cam shaft was "wiped out"?  Thanks.

Jeff

[Brad Ipsen CLC #737]

There is no restrictor in the oil feed line to the lifters.  The fitting pictured previously is typically used for the feed to the oil filter to restrict the flow in a bypass system.  See the picture on page 62, Fig. 40 in the 1942 Shop Manual for the complete oil system.

[Bobby B]

Jeff,
   If they used a new or "reground" cam, either the mushrooms needed to be replaced with new ones or they needed to be resurfaced to take out the profile worn into them from the old camshaft. Who broke the camshaft/engine in? The first 15 minutes of run time should have been done with either a  straight weight 30 oil , break-in oil, etc. along with some ZDDP additive so the metal-to-metal contact in the engine doesn't destroy itself. I don't want to get heavily into this, but there are specific guidelines when breaking in a flat-tappet motor. Was the engine already assembled with camshaft assembly lube on the cam and lifter bases and other crucial areas? You never answered the question regarding the valve stem tip to cam heel clearance which is crucial to this engine. Did the machine shop have flathead experience or some kind of spec sheet for the 346 to go by? If they changed the valves, guides, etc. , they needed to establish that 3" space when doing the valve job. All the stems need to be custom fit against the cam heel lobes and usually ground to arrive at the 3" benchmark. It's a tedious job, but did they do it? If you had a new cam, you needed to either follow the cam manufacturer's specific break-in instructions, or use some general guidelines which are available all over the net, which involve specific rpm's, oil/ additives, timing, etc.  This is not a Chevy 350………Just trying to help you out with this.         Bob

[Bobby B]

Brad,
I've taken 3 of these 346 motors down in the past 2 years ('46,'47', and '48) and all three of them had NO filter, but had the restrictor or "metering" fitting in the block for the supply line to the lifter valley. Maybe they put some in, and/or left some out? Any other opinions/ fact on this?  Now, I'm curious…..

                                                                    Bob

[Jeff Trahan]

Thanks, Bob.  I appreciate your patience.

I gave the military manual (which I found online) and the regular shop manual to the rebuild shop when they were working on my engine.  I don't know if they set the distance to exactly 3".  I filled the crankcase with Lucas SAE 20 break-in oil before starting.  Then I more-or-less followed the break-in instructions from Walt's Workbench on breaking in a rebuilt Cadillac flathead. http://www.rmrclc.com/waltsWorkBench.html

Jeff

[Bobby B]

That's all good and a step in the right direction so far! Find out from the machine shop how they handled the cam/ lifter situation and the clearance from cam heel to valve stem tip of 3". If that's all good, you're going to be doing some detective work! Keep us posted so we can try and help you out on this.
                                         Bob

[Jeff Trahan]

I found the old lifters in a box I got back from the engine rebuilder so I guess they installed new lifters.  I'm assuming the rebuilder re-assembled the engine using the correct specs, but I'll give him a call to ask.

[Bobby B]

Jeff, Good deal…..The 3" spec is important and might be the culprit of the noisy valve train. Did you get the lifters and the mushrooms tappets back, or just the lifters?
                                                                                                                     Bob

[Jeff Rosansky CLC #28373]

To answer your question about why everything needs to either be new, or matched.  Think of it as like sanding a piece of wood.  Run the sandpaper in one direction only and then it matches.  Turn the piece of wood 90 degrees and the sandpaper will really eat into the wood.   Everything wears and matches itself to where ever it is.  You can't see it, or even feel it, but everything matches in the wear pattern in which it lives.  Up/Down, side to side.  they match the cam or wherever it rides,etc.  If you swap them, then they have to re-match themselves.  And then the hole/valley/lobe in which the mismatched item is in, then wears itself again.  So, everything has to re-wear itself so that now your cam has a wear pattern from the first lifter, and then now the second,etc. 
If you go new to new, then it will wear and match itself.  If not, then go old to old so that it doesn't have to change much.
Best of luck.  I am almost in the same boat as you.  The engine for my 70 it in the shop now and I hope to be installing it soon.
Jeff