'34 21 stud - no oil pressure ** Update 7/17 **

daddy_o's_diner

daddy_o's_diner

Junior Member
I just purchased a '34 five window that was restored in 2003. The owner passed away just has he was finishing the car. Since '03 the car has been started a few times a year and was driven in a parade in 2009.

When I got the car home. I had to replace some fuel line before I could get the running. Upon initial start up the oil pressure was about 8lbs at idle and would climb to about 15lbs when engine was revved. I felt confident enought to take it for a short drive. about 1/4 mile from home the oil pressure drops to 0. I'm think about just trying to change the oil pump??? any thought or suggestions? This is my first flat head so I'm needing some advise.
 
Last edited:
Re: '34 21 stud - no oil pressure

First I would change the oil to 20-50. Then I would attach a mechanical pressure gauge to where the oil sender unit is. Then start it up and see what the real pressure is. The dash gauge is not reliable enough to start making major changes. John
 
Re: '34 21 stud - no oil pressure

Thanks

Gauge is older mechanical. I'm going swap it out for a known good one. I'll try the 20-50.
 
Re: '34 21 stud - no oil pressure

The flathead pump system is simple and sturdy, but there are a couple ways it can fail, as distinguished from just slow deterioration in pressure from general wear.
If the drop to nothing turns out to be real, it is possible that accumulated crud from storage came loose...a nice mouse nest or some such...and totally blocked the pickup. Also, a '34 would still have the drive gear on the rear of the cam that turns the pump made with a round hole pressed onto a round shaft. Later ones have D-shaped hole and shaft. The round setup can slip and rapidly wear to free fit on the shaft if something (again, possible crud) gets into pump teeth and adds resistance.
 
Re: '34 21 stud - no oil pressure

there are only a few places that would cause no or low oil pressure, oil pump, cam bearings, my guess if engine doesnt knock, and main bearings, but as was stated, use a good mechanical gauge to see if you really have a problem, if you do have the problem it starts to get expensive, so find the problem before you start spending lots of money
 
Re: '34 21 stud - no oil pressure

Foreign particles could be holding the bypass valve in oil pump open and no pressure is the result, or pressure relief valve in block.
 
Re: '34 21 stud - no oil pressure

The engine appears to have been rebuilt in '03. I'm trying to verify this with someone familiar with the car. Should know tomorrow. It was stored in a clean, dry pole building and there is no signs of rodent damage anywhere. Looks clean with some dry rot of belts hoses, etc...

Another problem popped up. Car has 12 V generator and was wired just enough to run. While tinkering around last night I left the ignition switch on. About 1/2 hour later the coil overheated and exploded.

Now I need to find/buy a coil and probibly pull the pan just to determine its likely junk.

I it is, i'll upgrade to a 24 stud or possibly even a y block. So I hate to spend a lot of time and money on this engine.

This whole "first flathead" thing isn't off to a great start.
 
Re: '34 21 stud - no oil pressure

Actually, Flat heads usually do not have problems with oiling unless the whole thing is worn out. If it is a fresh rebuild, I would tend to think the front galley plug was left out or the pressure relief valve in the valley was left out or missing the spring or plunger, or if it has a late pump, the pressure relief valve in it is stuck open.

After you varify (with a different "known to be good" mechanical pressure gauge) that the engine does have very low oil pressure, then I would address the other posibilities.

Also, flatheads do not like thin oil. You can successfully run 10-40 or if it is really hot, 20-50. However, even with thin oil, it should have more oil pressure then you indicate.

Question? How does the engine sound when it is running?

Do not give up quite yet. I have many thousands of miles on 21 stud flat heads with very satisfactory results.

NOTE FOR OTHERS ABOUT OIL AND FLATHEADS, I AM SPEAKING FROM MY EXPERIENCE AND THIS IS JUST MY OPINION ABOUT WHAT OIL TO RUN. I DO NOT MEAN OR INTEND TO START A BIG MAJOR DISCUSSION ABOUT WHAT OIL IS GOOD OR BAD OR WHAT EVER. THIS IS JUST MY OPINION, THATS ALL.

Let us know how you make out,

Chris
 
Re: '34 21 stud - no oil pressure

I really appreciate all the suggestions. It's gonna be a little while until I can check things further. I have to dig up another coil and get that mess sorted out first.

One of the main reasons I am leaning toward giving up on the 21 stud is the lack of speed and dress up parts for the engine. You see, I am one of those pesky Hot Rodders from the HAMB. :eek:

I would like to run the 21 stud until winter then ungrade the powertrain.

Don't panic!!! It will be a very traditional build. NO CHOP, full fendered, unsplit bones etc... nothing that can't be undone at some point. I'll try to post some pics tomorrow.

Anyone have a coil for me? I've heard there is an external coil conversion kit - who sells it?

Thanks again,

Dave
 
Last edited:
Re: '34 21 stud - no oil pressure

most of the catalog places have the external coil kit....and there are hop up items for the 21 stud....Eddie Meyer heads, etc....mechanical gauge where the pressure sender is should tell you whether you have pressure or not...maybe some MMO in the oil when you change....some in the gas, too....good luck....Mike
 
Re: '34 21 stud - no oil pressure

Daddyo, Dave, there is hot up gear available for 21 stud motors. I run a water pump in head 21 stud engine that is very nicely worked over- it pulls 7000 RPM! Just about any part is available- it just costs- but then again all speed equipment does doesn't it? Brian
 
Re: '34 21 stud - no oil pressure

Here are a few pics. Don't mind the wheels, they're just a set I had laying around. I'm thinking of some black 16' spokes or some '40 Ford 16' done in black with trim rings and chrome lug nuts.

The pic of the later flattie is an engine my friend has had laying around for awhile. If I'm going to have to rebuilt one, I'm leaning toward convincing him he needs to sell it to me and going that route.
 

Attachments

  • flattie.jpg
    flattie.jpg
    21.7 KB · Views: 51
  • '34 with blue wheels.jpg
    '34 with blue wheels.jpg
    20.8 KB · Views: 40
  • rear with red.jpg
    rear with red.jpg
    21.4 KB · Views: 40
  • '34 and '54 front.jpg
    '34 and '54 front.jpg
    20.5 KB · Views: 38
  • interior shot.jpg
    interior shot.jpg
    19.7 KB · Views: 40
  • 1278005605695.jpg
    1278005605695.jpg
    24.8 KB · Views: 45
Re: '34 21 stud - no oil pressure **Update 7/17**

Ok, I got the external coil wired up and installed a known good oil pressure gauge with new tubing running to it. I also filled the crankcase with 20-50 as suggested.

Upon start up I got 16 lbs @ idle (about 650-700 rpms) and 26 lbs @ 2000 rpms. Pressures were slightly lower when engine warmed up.

No knocking just and ignition miss and a couple exhaust leaks - :o

Is this sufficient oil pressure to get me through until winter? I will then decide to throw in a later flattie or an early OHV V8 (remember, I am one of those damn hot rodders - LOL).

Thanks again for all your suggestions.

Dave
 
Last edited:
Re: '34 21 stud - no oil pressure **Update 7/19**

sounds good to me....run it 'til it dies...then decide whether you need an engine with valve covers...lol....have fun....Mike
 
This is directly copied from my manuals on CD. This is from TSB 6000.

Normal oil ​
pressure at 2000 RPM 30 lbs.
Oil pump 1.88 gallons per minute at 2000​

RPM.

I don't think you have any thing to worry about.
 
daddy o's diner, I have a stock car, a street rod, a custom and a other brand its your car you can build it your way but keeping a flathead in your 34 would be nice. good luck. Harold cebtral coast Ca.
 
That's enough oil pressure but if you want more here's what to do. Remove the intake manifold and spark plugs and at the front under the manifold is a large nut. Remove the nut and there will be a spring and plunger. Make a spacer out of a 1/8th inch brass pipe. Start out with one 3/16" thick. This will sit on the top of the spring and the ID of the brass should clear the OD of the plunger. Tighten the nut and put a little oil in all cylinders, lay a rag over the cylinder holes. With a mechanical oil pressure gauge installed spin the engine with 12 VOLTS and see what pressure you have. You should be able to get 50 lbs, the pressure can be adjusted by the thickness of the shim, thicker shim more pressure, thinner less pressure. Don't streatch the spring it don't stay there. G.M.
 
You must log in or register to reply here.
Back
Top