Stromberg M-5 carb. Mine is unusable, and I need to find a replacement.

[Day Radebaugh]

I'm trying to restore a '21 Seagrave firetruck, which currently has a Stromberg M-5 carb.  Mine is unusable, and I need to find a replacement.  As an alternative, this truck could use a Marvel-Schebler Model A (not Ford model A, M-S Model A type carb).  I would appreciate knowing of any such carbs that might be for sale (rebuildable core OK) or to direct me to someone who might be knowledgeable.  I'm prepared to substitute a suitable updraft carb, and would also appreciate any information on what might be an acceptable updraft substitute.  This carb feeds a fairly large (10 liter) engine.

 

Thanks

[wayne sheldon]

Welcome to the forum! 

This week is a bad time to be asking difficult questions. Too many of our best and brightest are busy with Thanksgiving week visits, preparations, and etc. I recommend bumping your query up a few times into next week when many will be back.

 

What makes this particular carburetor "unusable"? Usually, these type brass carburetors are fairly bulletproof. While many little pieces may be damaged or lost, with a little creativity, almost any piece they may need can usually be made with basic shop tools.

 

Usually, when we deal with an "unusable" carburetor it is because back in the day, a lot of them were made using a type of "pot-metal" wherein the chemistry wasn't fully understood in the day. And after a couple decades the main body and other critical pieces began to disintegrate due to an incompatibility of metals used in the mix. When that happens, often it will happen to all of a given model of carburetor as all of them were made using a similar metal mix. Often then, nearly all of them after nearly a hundred years have become unusable, and the only reasonable remedy is to find a suitable replacement. Suitable replacements for large displacement engines can be difficult to find.

[carbking]

The number "5" after the model letter with most Stromberg carbs, including the M, represents the S.A.E. flange size. Thus this carb is an S.A.E. size 5.

 

Other size 5 carbs:

 

Zenith L-8 - brass (opinion) very good for the day

Schebler D - exact number unknown - brass (opinion) the first Schebler, and the best Schebler, especially for low speed engines.

Schebler A - exact number unknown - brass (opinion) wasn't usable when new

Schebler S - exact number unknown - brass marine (opinion) same as above

Stromberg MT-5 - brass the tractor version of your M-5 (like the Zenith L, very good for the day)

Stromberg - cast iron SF-5 or SFM-5 (opinion) one of the finest updraft carbs ever built

Zenith - cast iron 63AW16 or 263M2E16 (marine) (opinion) one of the finest updraft carbs ever built

 

The above are physical sizes.

 

Once the physical size has been determined, one must then determine the proper internal venturi size which will probably be different than what one has, and require fabrication.

 

Like Wayne, would try to rebuild what you have; I see you have one of my kits. Will be glad to attempt to help answer questions. 573-392-7378 (9-12, 1-4 Mon-Tues central time).

 

As Wayne mentioned, these large carbs can be quite difficult to find. In 50 years we have had 1 size 5 Schebler D, 1 Stromberg M-5, and 1 Zenith L-8 of the brass versions. We have had several of the Stromberg SF-5, acquired when we purchased the remains of Stromberg, and several of the Zenith 63AW16, acquired when Zenith obsoleted the series. Most of these are long gone.

 

EDIT: just checked the Rayfield literature, and Rayfield offered a model G-6 brass carb. I have never seen one.

 

Jon

Edited November 23, 2023 by carbking (see edit history)

[Day Radebaugh]

Thanks very much for the information.  I believe what makes this carb unusable is the broken idle tube, as shown in the attached. Update-- I have just found a Stromberg M-5 at https://northfieldltd.com/index.html  When I contacted several rebuilders, they declined to work on this carb, and I'm assuming the broken tube was the reason.

[carbking]

Day - any GOOD carburetor rebuilder would simply replace the idle tube where it attaches to the lower holder.

 

Guessing in most cases, the rebuilders you contacted were unfamiliar with the Stromberg type M; and may be "parts replacers" rather than rebuilders.

 

I no longer have time to rebuild, but would have been happy to rebuild your carb when I was still rebuilding.

 

If you are doing the work, boil that carb in an ultrasonic cleaner before trying to remove anything else. Patience is your friend, don't try to force anything. You will probably have to fabricate (or have fabricated) a new venturi, as the original pot metal ones grow, and crack. I do not have any of the various sizes for the M-5.

 

But I do have a good used idle tube and holder assembly for the Stromberg M-5.

 

I have had several conversations with a company called Carburetor Specialists. I have not seen any of their work, but they tell me they do work on antique carburetors. Their number is (678) 393-1501.

 

Jon

[edinmass]

Too many shops/people call themselves “carburetor rebuilders”. In my experience today, 99 percent are parts changers who order a kit from anywhere they can find……and just turn them around without checking application and making sure what they have in hand is actually correct for the person’s vehicle. Every vehicle has a different calibration for its installation, and if you don’t have the prints/information on hand, you are wasting time and money. Running changes during the production year also needs to be considered. Very few people really have on hand what is needed to do a proper job. I regularly see “professionally rebuilt” carburetors on cars running like crap…….and when I open them up most of them haven’t even been completely disassembled and cleaned properly.

[Day Radebaugh]

Thanks, guys, for the comments and information.  I'm curious how a genuine rebuilder tests a rebuilt carb.  What is the device they use to test the flow of fuel, and how it responds to changes in throttle/choke?  I vaguely remember hearing about a "flow bench" which tests the actual performance of the carb under simulated dynamic conditions.  This particular carb is on a '21 Seagrave Standard (see attached picture) whose engine is about 10 liters or more.  Would there be specifications for the setup of this carb that a genuine rebuilder would have access to?  

[edinmass]

We only did limited specially work and had several running platforms that we tuned on a dyno, so we were able to keep notes on all our projects. Realistically it’s too expensive for most applications to actually test the units before shipping. Nice truck. I would recommend the fire truck sites for additional help, as ten litre engines certainly are a world of their own. Fire truck guys are very helpful and many of them have hoards of parts. The giant speedster guys may also be an area to check out.

[Day Radebaugh]

Thanks, guys, for the comments and information.  I'm curious how a genuine rebuilder tests a rebuilt carb.  What is the device they use to test the flow of fuel, and how it responds to changes in throttle/choke?  I vaguely remember hearing about a "flow bench" which tests the actual performance of the carb under simulated dynamic conditions.  This particular carb is on a '21 Seagrave Standard (see attached picture) whose engine is about 10 liters or more.  Would there be specifications for the setup of this carb that a genuine rebuilder would have access to?  

 

Thanks very much.  I've learned a lot about carbs in these posts.  I don't know if anyone at the AACA forum cares about fire engines, but I have 2 on my restoration agenda now.  This Seagrave is in fact the first motorized fire engine our little town ever bought.  It has a lot of local history with it.  The story is that our town's water pump failed soon after this truck was acquired, so they put it to use supplying water pressure for our little town of several thousand people.  It kept the water flowing for several days without a problem.

 

Therefore I am motivated to restore this and put it on display at our various parades.  I just rebuilt the ignition using original parts (distributor, rotor, points etc) and now have to get this carb fixed.  I have it running on the current Stromberg but it leaks like mad and does not run well.  As you can see, the firetruck's sheet metal is in great shape, so the rest of the work should be quite straightforward.

 

I appreciate your help.

[carbking]

Day - no offense meant, but your "10 liter" engine size is giving me fits.

 

I don't know when the USA started using engine liters, but it certainly did not in 1921! Illiterate cat owners used "liters" in boxes

 

ALL of my records for USA engines are in cubic inches. Of course, my database ends with 1974.

 

According to Stromberg, the Seagrave Firetruck in 1919 and 1920 was their own 6 cylinder of bore 5 3/4 inch and stroke  6 1/2 inch. According to Branham, this engine was used through the 1924 model year.

 

So my calculation is (5.75/2) quantity squared multiplied by pi, multiplied by 6.5 multiplied by 6 equals 1012.7 cubic inches is 16.6 liters.

 

The carburetor used was a Stromberg M-5 identification number A-5915. And yes, I DO have the specifications on this carburetor. The third issue of the Stromberg card was issued in the Detroit office 1 April 1920 (please, no April fools stories, that is the date on the card).

 

Jon

[Day Radebaugh]

No offense taken. Someone from 1921 would not have known what you were talking about in describing engine size in liters.  But your calculation expresses my point even better, which was to simply say this is a big engine.  And, with respect to carburetors, the implication would be, I suppose, that it needs a carb that is capable of supplying a whole lot of gas when under full load, which it would have been when it was pumping water for several days to supply the residents of my home town of El Dorado, KS.  And, as I understand this Stromberg, it has a idle circuit and a high speed circuit, which suggests to me that it regards the engine as either idling or full bore, and not something that requires a broad range of fuel amounts, such as would be needed if the truck were driven at a whole bunch of speeds in traffic.   Even driving to the fire may have been a "full bore" scenario.   Our joke around these parts is that the fire department gets there in time to save the building foundation.

 

In fact, this carb reminds me of something you'd find in a toilet tank.  This firetruck is sort of a big, stationary engine bolted to a transportation platform.  My usage, when restored, will be to drive it in parades.  I also found a pump, and would love to pump some water at local events.  When I acquired this truck, the pump was gone.  It's all brass or bronze, and I thing the junkman got its original pump decades ago.

 

Cheers!

[edinmass]

What scrap was high back fifteen years ago, a Seagrave pump stripped down to pure was worth about 3k. Lots of trucks went to scrap.

[Terry Harper]

22 hours ago, Day Radebaugh said:

And, as I understand this Stromberg, it has a idle circuit and a high speed circuit, which suggests to me that it regards the engine as either idling or full bore, and not something that requires a broad range of fuel amounts, such as would be needed if the truck were driven at a whole bunch of speeds in traffic.   Even driving to the fire may have been a "full bore" scenario. 

I suspect that the RPM range of this engine is rather limited. I am also assuming since it runs a pump that there is a governor. For comparison we have a 1919 Sterling T-head (962 cid) that will idle down to 400 rpm with 1,400 (150 h.p.) being the maximum. The Wisconsin T-Head (1,090 cid) which was used in some Stutz fire trucks was I believe 500-1200 rpm (110 h.p., Stromberg M4) Regardless, they do indeed love lots and lots of fuel! Both can burn through about 8 gallons per hour under load.

 

 

Edited November 26, 2023 by Terry Harper (see edit history)

[Day Radebaugh]

Quite right; fuel efficient it aint.  

[ron hausmann]

Day,

    Stromberg sold dozens of adapters in the 1910’s and 1920’s which allowed you to use one size carb flange to attach to a different size. I’ve got their catalogue in fact. That SAE size for Stromberg, means the c-to-c measurement between flange bolts at the intake, as carbking says above. There is I think a 1/4” difference for each size. I’ve never seen a Stromberg M5. I have seen Stromberg M4 carbs and they are occasionally on eBay. Both are big orifices.
   If I were you, and not planning on racing my Seagrave, I would buy a Stromberg M4, and buy or build a small adapter to mount it to your M5 flange. Other connections for gas and carb controls would be identical.

   Trivia - (Stromberg M4 carbs were original equipment on 1920’s Revere cars which had Rochester-Duesenberg engines). Big beasts.

   Ron Hausmann P.E.

[carbking]

Ron - I am going to disagree slightly with your post above.

 

Stromberg DID produce dozens of different adapters to adapt carburetors of different flanges to intake manifolds, HOWEVER: GENERALLY, adapting a carburetor of a different size would have been recommended if replacing some of the truly inefficient carburetors by size with a Stromberg. Without actually pulling prints, one would never want to replace a Marvel or a Schebler, or ???? with a Stromberg of the same PHYSICAL size, as the engine would then be grossly overcarbureted. Not throwing rocks (this time  ) at either, but neither would flow as much air for a given physical size as a Stromberg or Zenith due to the design of the carburetor. Marvel had their "spacer block" (actually the low speed venturi) which blocked almost half the throttle area.

 

Replacing a Stromberg (or Zenith) with a smaller carb, may in some instances, be possible; but a larger venturi would be required than the venturi in the carburetor being replaced. And while the inside diameter of the main venturi is a good portion of the air flow, a smaller throttle bore will somewhat restrict the air flow if 2 identical venturii in different physical size carbs are compared.

 

An example with the SF series (if Stromberg published flow ratings on the M series, I have yet to see the document);

 

SF-5 with 1 9/16 inch venturi was rated at 298 CFM at 2 inches Hg.

SF-4 with 1 9/16 inch venturi was rated at 284 CFM at 2 inches Hg.

To get the SF-4 to flow 298 CFM, one had to use the 1 5/8 inch venturi.

298 CFM was the ceiling on the SF-4.

The SF-5 would flow 334 CFM with 1 3/4 inch venturi. 

 

Generally, replacing a Stromberg or Zenith size 5 would be done with another Stromberg or Zenith size 5. The Stromberg SF-5 or SFM-5, or the Zenith L-8, 63AW16 or 263M2E16 would be size 5 replacements.

 

Parts for the M-4 are just as difficult as parts for the M-5, and one would need to do some engineering to pick the optimal venturi, and then recalibrate for this venturi size. Not saying it cannot be done, but the costs of several hours of research would have to be considered.

 

Jon

Edited November 26, 2023 by carbking (see edit history)

[ron hausmann]

Thanks carbking.

   You have superior knowledge as to these applications. And certainly are more correct.

   I would likewise not recommend interchanging different sized Stromberg carbs with Zenoths or Marvels.

   However, I have had good luck and success when interchanging different sizes and models of near-year Stromberg carbs. Stromberg OS-2 for Stromberg LB-2; Stromberg OS-1 for OS-2; and the like. Perhaps interchanging of Strombergs only is more conducive to success than other makes? Indeed, I switched out my LB-1 on my Sedanlette with a Stromberg OS-1 and the car seemingly runs with more power. I know that the Venturi flows are different, but not by much, so for these less-driven cars, I don’t think that exactness really matters. 
   His best solution would certainly be making the M-5 work. But maybe interchanging a Stromberg M5 for an M4 gets this persons car running, so at least it can be enjoyed. While he waits years for locating a correct Stromberg M5. It won’t hurt anything and get the car going.

   Take care. 
   Ron

 

[Day Radebaugh]

I appreciate those good suggestions, and I must say, in all honesty, that this one of the most helpful forums I've ever consulted.

[Dandy Dave]

A good machinist can make the parts that you are missing. I would go that route. Once one understands the way the fuel flows though a carburetor, and what keeps it from leaking when it is not running is 90 percent of the battle. Where in the world are you located?

[Day Radebaugh]

I'm in Kansas on a farm about 60 mi NE out of Wichita.  I keep the farm going and restore old trucks in my spare time.  I've never had to search for parts as I've had to for this carb.  Most of my searches, for example, have been for vehicles such as a '63 Mack I restored, and the availability of parts was challenging and getting worse but by no means as difficult as the antique car market, where some of these parts have to be remanufactured.  For example, I ran across a place recently--https://www.carbs.us/ that said they'd remake my carb if I sent them the original.  I was astonished at such an offer, and will have it done if I end up having no other option.

[Zimm63]

2 hours ago, Day Radebaugh said:

I'm in Kansas on a farm about 60 mi NE out of Wichita.  I keep the farm going and restore old trucks in my spare time.  I've never had to search for parts as I've had to for this carb.  Most of my searches, for example, have been for vehicles such as a '63 Mack I restored, and the availability of parts was challenging and getting worse but by no means as difficult as the antique car market, where some of these parts have to be remanufactured.  For example, I ran across a place recently--https://www.carbs.us/ that said they'd remake my carb if I sent them the original.  I was astonished at such an offer, and will have it done if I end up having no other option.

Check them out very carefully before sending a rare piece.  Or any piece for that matter.  There used to be a place called Karb King in Pittsburg (nothing to do with Jon) that was an outright scam.  

[Terry Harper]

Yes, be very Leary. In fact I would avoid doing that. Your average rebuilder isn’t going to have that part on hand and I seriously doubt they have the ability to make the part. it akin to finding a true commercial body person today who can actually skillfully hammer and work a panel back into shape versus simply changing it out.
 

Your best bet is finding a machinist to make a new idle tube. ask if they can make that specific part - not rebuild the carb. 

 

Your just one part shy of having a good, hard to find carburetor - don’t risk wasting time and money AND losing the carb.

[carbking]

16 hours ago, Day Radebaugh said:

I'm in Kansas on a farm about 60 mi NE out of Wichita.  I keep the farm going and restore old trucks in my spare time.  I've never had to search for parts as I've had to for this carb.  Most of my searches, for example, have been for vehicles such as a '63 Mack I restored, and the availability of parts was challenging and getting worse but by no means as difficult as the antique car market, where some of these parts have to be remanufactured.  For example, I ran across a place recently--https://www.carbs.us/ that said they'd remake my carb if I sent them the original.  I was astonished at such an offer, and will have it done if I end up having no other option.

In a different lifetime, when I had more time on my hands, I have reproduced brass individual carburetors. It was EXTREMELY COSTLY, but both were for exceptionally scarce vehicles, and the customers didn't object to the cost.

 

In todays world, with 3d printing (can brass be 3d printed), I don't know what the costs would be; but a bunch more than just reproducing an idle tube.

 

Jon

[wayne sheldon]

Stan Howe was considered by many people to be the world's best antique automobile carburetor specialist (no offense to Jon/carbking!). Stan was a brilliant and energetic fellow (auctioneer, writer, musician, and antique automobile hobbyist). Sadly (not unexpectedly), he passed away a couple years ago while working in his shop (he was in his 80s!). He had had a small machine shop, and was proficient in machinist work large and small (had a watchmaker's lathe!). For antique automobile work, he specialized in antique era brass carburetor rebuilding. He knew, truly understood, how a carburetor worked. He could make any part they needed, and had a couple engines of different sizes set up to test run carburetors and aid in their adjustment. He was considered by many to be the go-to guy for early carburetors, and rebuilt many of the rarest of the rare of them for private collectors and museums all around the world.

Ten years ago, several people would have quickly sent you to Stan Howe. Also, ten years ago, before he retired, Jon/carbking here was still rebuilding carburetors for collectors all over the world, and would have done just as well with it! Unfortunately, a lot of the hobby's best craftsmen are slowly going away.

 

Maybe we should just chain Jon to his workbench? (Just KIDDING!)

[Terry Harper]

13 minutes ago, wayne sheldon said:

Stan Howe was considered by many people to be the world's best antique automobile carburetor specialist (no offense to Jon/carbking!). Stan was a brilliant and energetic fellow (auctioneer, writer, musician, and antique automobile hobbyist). Sadly (not unexpectedly), he passed away a couple years ago while working in his shop (he was in his 80s!). He had had a small machine shop, and was proficient in machinist work large and small (had a watchmaker's lathe!). For antique automobile work, he specialized in antique era brass carburetor rebuilding. He knew, truly understood, how a carburetor worked. He could make any part they needed, and had a couple engines of different sizes set up to test run carburetors and aid in their adjustment. He was considered by many to be the go-to guy for early carburetors, and rebuilt many of the rarest of the rare of them for private collectors and museums all around the world.

Ten years ago, several people would have quickly sent you to Stan Howe. Also, ten years ago, before he retired, Jon/carbking here was still rebuilding carburetors for collectors all over the world, and would have done just as well with it! Unfortunately, a lot of the hobby's best craftsmen are slowly going away.

 

Maybe we should just chain Jon to his workbench? (Just KIDDING!)

I was fortunate to purchase parts for my M4 from Stan just before he passed. Certainly a gentleman and craftsman from another age.

[carbking]

Wayne - thanks for the comparison, Stan was great.

 

There was another one some 40 or 50 years ago, whom some of the older members here might remember, Jim Roe in Seattle. I believe Jim and Stan were contemporaries. But too many cigarettes and Jim passed way before his time. I miss him, he was one of my two mentors in the carburetor business. I started with just rebuilding carburetors, and he was a great mentor. There just weren't any parts. So I started supplying repair kits, and slowly the rebuilding kits business took over the rebuilding business (for me).

 

Jon

[CChinn]

Based on my short time as a forum member (approx 1 year), it seems to me that carbking (Jon) is the natural successor to both Jim and Stan as the carburetor 🐐. I learn something new, interesting and informative with every post he makes. He Is always providing helpful advice to every carburetor question. Thanks Jon!  He is just one of many contributors here who makes this an enjoyable and educational daily reading experience 

[Day Radebaugh]

Update, guys: I found myself just surfing around the net recently and I came across https://www.vintagecarb.com/index.html. Rand Broadstreet had a good M-5 core which I bought and he has shipped it down to Jeff Dreibus, the Old Carb Doctor (http://www.oldcarbdoctor.com/) in NC.  I spoke to Jeff and we agreed that I would send my old carb down to him in case he needed any parts from it.  My overall objective is just to get one good running carb from the deal.

  

I've decided not to send my old carb to Carburetor Specialists because of the expense and the fact that I expect to get back a perfectly adequate carb from Jeff Dreibus.  Comments are welcome, as usual.

[Mark Gregush]

Pretty sure I have seen his listings on eBay. Thanks for that link.