Low oil pressure in a Model "B" engine follow-up

[Marshall V. Daut]

I'm posting the apparent solution to what had been a vexing low oil pressure concern in a friend's professionally rebuilt Model "B" engine with insert bearings in his 1928 Model "A" Sport Coupe. My posted question last week didn't get many public responses (like, ZERO), but I did hear off-line from three knowledgeable Model "B" guys, who offered great advice and printed documentation: Jim Brierley, Colin in Melbourne, Australia, and James Rogers of Dreamwerks. "Greg Out West" also provided some good information on "B" oil pumps and how to improve oil pressure and flow in a "B" block a few months ago when I was looking to modify the Kentz filter system. Past postings on the subject reaped good information and photos, too. But Vince Falter's website information on Model "B" oil pumps provided the definitive answer to my problem. Thanks to all for your input. Each little bit added up to help solve the problem.
Briefly, the problem simply came down to the need to use a Model "B" oil pump in a Model "B" engine. Duh! The problem "B" engine in question here had a rebuilt Model "A" pump with the straight 1/2" pump shaft, no relief. This wasn't able to pump enough oil to feed the oil filter or give a good oil pressure gauge reading. When their fittings were removed for checking oil pump operation while the engine was running, only a blurp, blurp, blurp resulted. Taking advice from the aforementioned experts and studying Vince's drawings and photo of a Model "B" oil pump shaft with a 0.10" relief along its shank, I decided that a Model "A" pump just couldn't provide the needed oil pressure. There was NOTHING wrong with the later Model " A" oil pump in this engine! It just operated differently in a "B" block with its alien non-Model "A" oiling system. Instead, I put in an NOS Model "B" oil pump with its relieved shaft Sunday and was flabbergasted at the improved pressure that resulted! It was so strong, in fact, that the fittings for the pressure gauge and oil filter leaked like crazy, something they hadn't even come close to doing when the Model "A" pump was in place. It took quite a bit of thread sealing and fitting tightening to stop the hemorrhaging of oil. But, wow! Instead of the paltry 1 or 2 psi delivered by the totally stock Model "A" pump (with the round exit holes), the pressure now reads 4-5 psi and steady. What a difference!
One other thing I asked about in my posting, as well as off-line, was whether the orientation of the oil pump drive gear housing made any difference. As readers may know, there are two "flats" on the housing in the area of the exit hole in the lower oil gallery. I turned the housing until one of the two flats was directly opposite this exit hole. I looked everywhere for an answer about orientation of this little devil, but nothing was mentioned anywhere. I assumed that was an answer in itself if the issue had not been raised on this website or mentioned in any Ford or restoration manuals. I can't say if the way I oriented the housing made any difference in increasing the oil flow (doubtful) or whether the change was due solely to use of a true Model "B" oil pump, but the problem appears to be solved.
Not being much of a Model "B" engine block fan, this was new information to me that I'll file away for future reference. Maybe reading the solution here to my problem may help someone else in a similar situation.
Marshall

[emf]

So, if I read this correctly, a Model B engine at operating temperature, running at 40 MPH should deliver about 5 pounds of oil pressure? If so, that is good news, since my B engine is doing just that... Cold, it delivers about 12 pounds, but after warm-up, 5 is the best I get. My mind can rest now...

Frank

[Marshall V. Daut]

Frank -
The original Rex-A-Co oil pressure gauge in this Sport Coupe only goes up to 5. Upon start up yesterday morning and today, the needle definitely hit 5 and might have gone higher. Maybe if the scale went higher, so would our reading. But 12psi??? Of the three Model "B" engines I've owned with various original and repop gauges, none reached quite that high. I think 8 or 9 was about the max I ever saw - and that didn't last long. Congratulations on attaining 12! I wish my friend's engine could do that because the sun rises and sets on that $%#*^% gauge with him and when it drops, so does his heartbeat rate - and I get a panicky phone call. I hope this NOS "B" pump puts an end to all that.
Marshall

[emf]

When I went to by my gauge from Bratton's, I wanted the Rex-A-Co, but they were out of stock, so I got the Apco. Maybe if I had installed the Rec-A-Co, my pressure would be lower, like yours...

[Benson]

Bill Kenz told me about this oil pump problem in 1976 when I was building a full oil pressure B Block for a Miller OHV setup.

I posted this info several times here in the past and was told publically on FB that NO Model B engine EVER gets more than 2-3 lbs oil pressure hot and in so many words that I did not know what I was talking about.

Even when I pointed out the Service Bulletin and stated that my B engine that was totally stock (all standard size parts) when rebuilt 25 years ago, gets 2 lbs hot at idle and 8-9 at 55-60 with the correct Model B pump.

I deleted the postings in disgust.

Just now I checked the oil pressure ... It has been years since I looked at it.
Pressure runs about 8-9 at 45MPH and about 10 PSI at 60 MPH with hot engine.


After an engine rebuilder told me that there is NO difference between the A and B pumps I decided to never mention it again.

[Marshall V. Daut]

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Benson -
You were ahead of your time - and you were right. "They" were wrong. As so often happens when people are ahead of the curve, others toss slings and arrows at them. Even a cursory look at a diagram of the internals of a Model "A" pump (but not the early ones, which also had relieved shafts) and a Model "B" pump invalidates "their" opinion that the two pumps are the same. Vince Falter's page on "B" pumps ought to settle this "debate" once and for all. It did for me.
"Oil Pressure" Marshall

[Bruce Lancaster]

A day spent on Vince's site and another on Marco's would probably make half the questions that arise here unnecessary. Amazing heaps of solid research!
I've spent a lot of time on each, and I notice new good stuff every time I go to either.
I hope I did not miss the answer to THIS over there, but what about the discharge opening at the top? I've seen several forms of slots and a couple sizes of round holes there. I bought a few random flea market pumps and found no consistent match of shaft size and hole. What goes with what? Is an A discharge different from B, or am I just seeing supplier differences and random drillings by experimenters?
By the way, the 1932 Service Bulletins speak here...there is a set of cutaway pictures of A, B, and 18 side by side, and the straight 29-31 type pump shaft is noted in UNDERLINED CAPS NEVER USE THIS SHAFT IN "B" ENGINES !!!

As with Vince's site, I find new stuff in the bulletins every time I look, even though I got my first repro set in about 1964 and I keep a set near every place I hang out!

[Marshall V. Daut]

Bruce -
Yes, that side-by-side drawing on Vince's website of the three oil pumps is the bit of information that clinched it for me. It very clearly shows AND tells which pump is right and why the others are wrong in a Model "B" engine.
Someone in the past had posted a photo on this website of five oil pumps lined up next to each other, ranging from an early 1928 pump without spring (but with relieved shaft), through the standard pumps we see everyday, and ending with a Model "B" pump. Not much external difference between them, other than the early '28 pump with the tall body. The main difference I noted was the exit holes, either being slotted or a round hole. Apparently the later Model "A" pumps had the round hole, which was in my friend's Model "B" motor. The pump that had been in there was broken at the top of the casting when we first dropped the pan. I replaced it with a rebuilt Model "A" pump with the straight 1/2" diameter shaft, not knowing there was a MAJOR design change internally. It had the round exit holes. Now I know that a Model "B" engine must use a pump with a relieved shaft to operate properly. The next time I see the friend, I'll ask to examine the old pump we removed in order to determine if it was a true Model "B" pump. Remember: this car had a hodge-podge of Model "A" and Model "B" parts, so it's anybody's guess which oil pump was in it.
Agreed: Vince's and Marco's websites are goldmines for us restorers. 'Sure wish such resources had been available when I first got involved in Model A's in 1966. I could have avoided a lot of stupid mistakes over the years.
Marshall

[Benson]

Marshall,

Here is a jpeg that I saved dated 2009. As I remember is was from a website of a fellow that rebuilds oil pumps and other parts.

I do not remember just now who it might be. I have not seen his ads in Model A Trader lately.

[Carter]

My rebuilt babbit bearing B pegs a 10 pound gauge cold, runs about 1 psi hot at idle, and around 7 psi hot at 50 mph.

Dave