Brand new Zenith updraft carbs

[ArticiferTom]

Viv , You correct on my '31 Dodge . It is a truck build by Graham Bros . they used the 196ci Plymouth 4 cyl Same as PA but called UT in the trucks . For six cyl. they used Desoto engines DD .

[JustDave]

Thank you carb king I knew if I talked to the right person I’d get the correct answer

[paulrhd29nz]

I find this topic to very interesting. 
I’’m a Hudson guy. My 29 Hudson that I have been driving regularly for over 30 years has its original muck metal Marvel carb on it. I am amazed at how well it performs. I have dozens and dozens of hours over those years of nurturing and finessing that card as the shape of its internal bits are constantly swelling and changing. When it starts to miss behave out comes the files. Im getting to the point now that I’m scared to touch it. 
it looks like it will shatter to pieces at any bump. I have over the years bought every one that I could get my hands on. All of them are junk. Years back someone had brass ones reproduce, but none are to be had. I’ve seen a lot 29’s with the intake flipped 180 and 60’s Chevy downdraft adapted to it. They run well but look like shit. I’ve also seen a few BB1 adaptations but have no idea of performance. I take great pride in the originality of my 29. The motor pulls incredibly strong and is an extremely well performing engine. When I take other cars guys for a ride they are all gobsmacked at how well it pulls a big four door sedan a round. 
I will be at a loss when that marvel shatters to bits and have always wondered what , if any options I might have for an updraft replacement. 

[carbking]

Paul - you have probably read I am not a fan of Marvel; however, since you are wishing to retain the "look" of your engine:

 

1927 Hudson used Marvel 10-661 type B brass bowl

1928 Hudson used Marvel 10-669 type B brass bowl early production

1928 Hudson used Marvel 10-690 type B zinc alloy bowl late production (same throttle body and heat riser as 10-669)

1929 Hudson used Marvel 10-725 type VB zinc alloy bowl.

 

The throttle body and heat riser for 10-725 differ from the earlier carbs; HOWEVER:

 

The heat riser gaskets for 1928 (10-669, and 10-690) are the same as the heat riser gaskets for 1929 (10-725)

The carburetor mounting gasket for the 1927 (10-661) is the same as that for 1928 (both)

 

So, with absolutely no proof other than the Marvel parts books (and so far the only two carburetor companies to embarrass me more often than Marvel are Kingston and Ensign  ), it appears that a 1928 heat riser would fit your 1929, and either the 1927 or early 1928 brass carburetors would fit the 1928 heat riser; thus you could have a brass Marvel on your car.

 

The actual part numbers are not stamped on the brass Marvels, but the casting number on the throttle body for 10-661, 669, and 690 all are 10 over 134.

 

In the for what its worth category, if it were mine and I wanted to drive it; I would tell everyone it was a 1926, and install the vastly superior Stewart carburetor from any of the early 1920's. Since I do not have a Hudson parts manual, I don't know how much would be required to make the change.

 

While not "common as dirt" the Stewarts for Hudson are available; and as you mentioned the brass Hudson Marvels have been difficult to find for a long time.

 

Jon.

 

 

[jdome]

I'm not a fan of modifying or upgrading cars or engine components. Making an old car run & drive with original components is just part of the ownership challenge and driver experience I enjoy in the hobby. The Zenith carb swap on the V12 is sacrilegious to me, I have a certain affinity for Cadillac 12 & 16s and the later V12 in particular. I don't have any hands on experience with the Johnson carbs but some of the frustrations can be blamed on the vacuum tanks.  Cadillac fixed all the 30/31 problems in 32 by adding the mechanical fuel pump, better distributor and the much improved Detroit Lube carbs. These improvements increased the HP rating of the 12 & 16 by 15 and 20 HP. A good running later 12 is a pretty good performer. Not as much mass as 1he 16 throwing around inside with more HP than the V8. The 12 pistons are larger diameter than the 16 so the 12 has more displacement and HP per cylinder than the 16. If Cadillac used the V12 bore in the 16 with the 32-37 improvements it would have matched the 500 cu in displacement and 200 HP of the Marmon V16.

 

Its  important to understand that these engines are 2 separate in-line engines with a single crank shaft. Each bank has it's own carb and manifold and coil. they do share the single distributor that has separate points and separate contacts at each end the rotor. You can actually disconnect one of the coils and the opposite bank will run fine dragging the dead bank at full compression. You can even drive the car on one bank but obviously with half the HP. I explain this because it doesn't take much effort to get the engine to run at somewhere between 50 - 100%.  To get to 100% requires that whatever carbs you use, the carbs are both in good condition and equalized, and all the linkage is in sink. Any imbalance between the 2 sides will degrade performance and run sluggish and may cause damage.  The strong bank pulls the weaker bank at a faster RPM than it is fueled which in effect, will cause the weak bank to run lean with typical lean burn issues; backfiring, popping back into the carb and potentially burned valves in the weaker bank.

 

The DL carbs are good reliable units and not too complicated and are re-buildable.  They are easy & simple to tune, if done right. They only have one mixture needle adjustment and an idle stop screw on each carb. But you can't adjust them without an "Equalizer", a tool that Cadillac made for these that connect a column of mercury to gage the vacuum in each manifold. I just use 2 identical vacuum gauges. The shop manual provides specific tune up procedure that should be followed.

 

[edinmass]

jdome........I agree that the Cadillac 12’s and 16’s run fine with factory carburetors. 30-31’s Cadillac-Johnson’s are junk, and a pain to get right......but you CAN get them right......it’s just money and time. The vacuum tanks work fine......I probably have 25k miles on 1930-1931 Caddy’s with the tanks.........and never had had any reliability issues........very long hills can cause fuel supply problems, and to overcome that it’s simply just a case of backing off the throttle every 45 seconds for about ten seconds and everything works great.(Only the 8’s have hill issues.) Cadillac’s are much better than average performers when properly set up......I would describe them as big and fast. Anyone who says a early 30’s Caddy is a truck or a tank has never driven a good one. Even the lowly 8 is a decent car.......... in a garage of great cars..........we drive our V-16  very often. Only Duesenbergs get more road time in our collection. 

[carbking]

I guess I get to be the "bad guy" in this thread

 

Quote jdome "I'm not a fan of modifying or upgrading cars or engine components. Making an old car run & drive with original components is just part of the ownership challenge and driver experience I enjoy in the hobby." End quote

 

About 50 years ago, I was at Hershey listening to two grey-beards that were about the same age then that I am now arguing about originality. The argument ended when one stated, and I don't remember the exact quote, but something like "well, if ask me, the car is no longer original when they change the air in the tires!"  (just pulling your chain a little  )

 

Quote edinmass "30-31’s Cadillac-Johnson’s are junk, and a pain to get right......but you CAN get them right......it’s just money and time." End quote

 

Ed - I can count on my thumbs with no repeats the number of folks I KNOW that can get the Johnsons right. How many do you know? But I will never do one unless the guy I was doing it for was one of the two  and I figure you would do your own. I would NEVER trust a Johnson that I did to a non-carburetor guru of an owner. I just could not sleep nights knowing I put some novice car owner in danger!

 

I would have absolutely NO qualms about recommending replacement of the Johnsons, even to hiring two 15-year-olds (one for each running board) to pour gasoline into both sides of the engine through leaky boots!

 

The Detroit Lubricators are a different story:

 

Quote jdome "The DL carbs are good reliable units and not too complicated and are re-buildable." End quote

 

I would disagree. The Detroit Lubricator carburetors, IF THE OWNER HAS A SET OF ORIGINAL, NOT MODIFIED BY DR. GOODPLIERS, CARBURETORS, are EXCELLENT, reliable units AFTER THEY HAVE BEEN PROFESSIONALLY REBUILT! Even though we offer rebuilding kits, we try to explain to the purchaser of the kits that their carbs, even if low mileage, are going to require machine shop services!

 

I have rebuilt a LOT of Detroit Lubricators over the years, and since Doug Heinmuller is no longer doing them, I probably have at least as much Detroit Lubricator information as anyone. But out of every 100 Detroits one sees, 96 of them are going to be "marriages" (Graham parts, castings done "somewhere" that shrinkage was not taken into consideration, parts from a dozen different carbs, etc.).  Detroits are expensive, and have been for at least 50 years. And not all swap meet vendors are honest, and not every car "mechanic" is a Detroit Lubricator expert.

 

If an owner called me wishing to replace Detroits with other carbs, AND HE/SHE HAD THE DETROITS, I would try to talk he/she out of the swap and getting them restored.

 

But a question for the folks promoting originality: what do you do if you purchase, or maybe inherit, a car missing the correct carbs, either Johnson or Detroit?

 

Jon

Edited December 29, 2021 by carbking (see edit history)

[edinmass]

Jon, it’s funny reading your comments that you will need machine shop service to rebuild a carburetor. To me, it’s normal and assumed that every pre war unit needs to go on the mill. Every unit we do gets placed into the jig and is squared up...........and that is one reason our rebuilds are so expensive. Set up time even with experience is time consuming. We just don’t do the gasket surfaces.......we do ALL the factory machined surfaces over again. Right now, if anyone needs V-12 or V-16 carbs from 1930-1937 I know where multiple used sets can be purchased. I don’t own them, but I know who has them on hand in inventory available for sale. Yup they are EXPENSIVE! But they come with a guarantee they are good usable cores. In the end, when one considers authenticity, performance, and ease of use.........I find 99.9 percent of the time factory units are best. Problem is most guys with a 1932 Hupp don’t want to do a 2000 dollar rebuild of a good UUR2. If your missing a UUR2 and need one correctly set up it’s gonna run you around four grand today. That’s a Pebble Beach quality job........and it’s the only standard we work to.......and I understand that takes 80 percent of the people out of the running for their driver type cars. We do try and help out people as often as possible......but we just can’t touch a carb with JB Weld holding it together............liability today is insane, and life and limb is more important. I’m a purist at heart.......and it’s ten times harder to make a early car work without modifications than swapping things out for “upgrades”. I find properly sorting a car and making it run 100 percent the most gratifying part of the hobby. Cars serviced correctly stop, steer, start, shift, and perform much better than most people realize in the era. Fact is, so many people drive cars with very bad habits they have no clue how a good car drives. 

.  

Edited December 30, 2021 by edinmass (see edit history)

[carbking]

Ed - my comments about the Detroits were not directed at the normal squaring up you mention.

 

The vast majority of the Detroits will require at least a new vane box, unless it has already been replaced. These were zinc alloy, and even if not broken, they will be severely warped. Add to this the wear on the upper edge of the groove on the aspirator valve, the significant wear on the vane "fingers", and the wear on the accelerator pump housing; and one needs machine shop services. As I have not been restoring carbs for several years, I am unaware of how many of these parts are currently available from other suppliers. We reproduced all of them 40 or so years ago, but I know we are out of the vane boxes, and may be out of some of the other parts as well.

 

While the professional is going to either repair (metal spray) or replace the aspirator valve, we suggest to the owners trying to not mortgage the farm to rotate the valve 90 degrees (the fingers will still need attention); but this will allow the aspirator valve to be used for one more rebuild.

 

And my guess would be you will be contacted about some of those cores.

 

Jon.

[edinmass]

Jon, it’s been a while since is did any Caddy 1932-1937 units.....but these are available new right now. 1932 V-12 units........... they are also making all 1932-1937V-12 & V-16 units. Nice people. I worked with them years ago on the Packard units...........

[edinmass]

Today I have a visitor at the museum, who owns the worlds best collection 1932 & 1933 V-16 Cadillac’s. Great guy, who actually drives and uses his stuff. Cant post names, but I’m certain you know him. He just added another 32 V-16 to the mix. 

Edited December 30, 2021 by edinmass (see edit history)

[TexRiv_63]

15 hours ago, edinmass said:

Jon, it’s been a while since is did any Caddy 1932-1937 units.....but these are available new right now. 1932 V-12 units........... they are also making all 1932-1937V-12 & V-16 units. Nice people. I worked with them years ago on the Packard units...........

If these would have been available when I had my 32 Zeniths would have never been thought of.

[jdome]

Now isn't all that gloss black and chrome plate hardware much prettier than that dull, non-descript zinc coating. I have a 35 and 36 and my carbs look similar to the 32/33 pictured with some differences. The 32/33 have the overflow vent on the edge of the bowl cover with the blue circle around the "V12". Mine have a red circle and no vent. Choke arm mechanisms are different too because 34-37 chokes are automatically controlled by thermostats mounted to the exhaust manifold above the carb. My cars have a separate primer, controlled by a knob on the dash where the manual choke is on earlier cars. Its been awhile since I showed a friend how to equalize his 32, but If I remember correctly, 32 has the same primer valve but it is linked to work in conjunction with the manual choke. Pull the knob full out and it closes the choke & primer. When engine starts you push the knob in to a run setting and that opens the primer. 

 

The primer on these carbs can be a headache if you don't know what to look for. The primer is just a valve that closes off a 1/8 inch hole thru the throttle body. The hole is normally open when engine is running. You close the vent to siphon raw gas from the bowl up to the cylinders during starting, then open it when it starts.  Any dirt or paint (ask me how I know) that gets in that hole and restricts air, will cause a very very rich mixture in that bank. The siphon action bypasses the mixture needle so any adjustment will have no effect.

[LewUnderCar]

I have been very interested in all the great information posted about Cadillac-Johnson carbs.  I have a 1931 Lasalle V8 Sport Coupe that unfortunately has never been able to leave my neighborhood under her own power, and my wife is quite "over" coming to tow me home.  I try to start the LaSalle every couple of months, and when I do it starts right up, idles well and revs while in neutral.  Every time I try to take her for a spin it seems she tops out at about 10 mph (won't accelerate beyond that) then in a block or so starts to miss, backfires through the carburetor and dies.   She won't start again until cooled down.  The previous owner removed the vacuum tank and installed an electric fuel pump & pressure regulator.  He had the carb rebuilt and the receipt shows numerous new parts plus being engine tested for performance.  The stock exhaust manifold to carb heating tubes are still in place.  Maybe there is too much heat for modern fuel? The car has been sitting and I also wonder if old fuel residue could cause such a dramatic lack of performance like I'm experiencing, or if it is something more serious.  One time (has not happened again) after a backfire through carb & die episode, fuel continued to pour out from the bottom of the carb until I shut off the fuel pump (I will heed the advice of Ed and others on steps to prevent disaster!) I assumed it was a stuck float, and after tapping the carb the problem went away.  Maybe this was unrelated to my primary problem?  Maybe I just need a bigger hammer?  The backfiring through the carb also makes me wonder if I have a timing issue.  Any help or ideas would be greatly appreciated.  I love the car but would love it more if I could drive it more than a block.

[Frank DuVal]

Starts good, just won't rev in gear, maximum speed is really low, then dies. Disconnect the exhaust system and see if it plugged. I know, not an easy task, but happened a lot on 70s GM cars with the "coaxial" pipe. The inner one would collapse, nothing seen from outside, baffled many a tech.

[edinmass]

Lewundercar.....I’m certain you have multiple issues. First of all, you need to take a compression test. I’m also certain you have ignition issues as well as carburetor issues. . 

[LewUnderCar]

Thank you for the feedback...I'll check exhaust as well as compression.

 

[m-mman]

On 12/31/2021 at 2:15 PM, LewUnderCar said:

and when I do it starts right up, idles well and revs while in neutral.  Every time I try to take her for a spin it seems she tops out at about 10 mph (won't accelerate beyond that)

Then you shift gears and it revs up (from "idle" to 700-1000RPM?) then you shift to 3rd and rev from "idle" to 1000 maybe 1500 RPM and you are then cruising at hopefully 35-40. 

 

I have a 29 Cad operating with its original vacuum tank. (electric pumps and Johnsons are not recommended) Mine doesnt stall but I have rarely been able to achieve the long wind out and torque curve from idle to top engine speed. It does act like it hits a rev limiter.  The Johnson carb master Ed has worked with mine and made it workable-livable, but without hundreds of his hours, a 5 gas analyzer and a dyno I dont think that it will get any better. 

 

FYI Johnsons have a double hinged float (originally cork?) and a weak needle/seat. I think they are happiest with just a gravity flow pressure and based on Ed's suggestions, I close my fuel valve and run it dry whenever I park it for any extended time. 

Whatever happens, do follow Ed's suggestions. 

[LewUnderCar]

Thank you very much...greatly appreciated information & guidance.   I checked the compression today and all cylinders are in the 100-110 range.  I keep looking for the "Auxiliary Air Valve" lever described in several tune up documents I have for the Cadillac LaSalle 1931 carbs...I do not see it...maybe mine was replaced with some other year?  My Block number (in the 800,000's) seems to indicate it is a very early 1931 engine, which makes it odd when I try to determine what instructions to follow in my "National Service Manual", that says 1931 cars start with block numbers 900,000.

 

Still trying to figure out why my old timing light won't fire despite being powered by a separate 12V bat. and not sure if I know what to do if it does decide to fire. (I've read that old dudes like me should challenge our brains in an attempt to keep the cerebral juices flowing. Me trying to wrap my pea brain around 6V positive ground electrical circuits is more than challenging for me).

 

[Frank DuVal]

On 1/2/2022 at 8:54 PM, LewUnderCar said:

 

Still trying to figure out why my old timing light won't fire despite being powered by a separate 12V bat.

Did you connect one of the + or - leads to the Cadillac chassis/engine? I do not think it matters which one, but I would use the -, even though it is positive ground. 

[Swear57]

Ok here goes. I have a Zenith updraft carb # 14995A on a 1913 Buick model 25 the small 4 cylinder. It starts on 9 or 10 pulls cold, once warmed up 1 pull. I won't say it runs great but it runs ok. The big problem is when I shut it off, it just runs gas out the intake. I have had this carb apart many times. It was on the car when I got it. It does not look that old. The inside is spotless. I saw where you take the needle out & take a 3/16 wood dowl put a point on it & polish the seat. I'm going to try that tomorrow. Maybe that will make it run better. Any other suggestion would be great. Thanks

  

 

[LewUnderCar]

Thanks again for the numerous ideas and suggestions regarding why my '31 V8 LaSalle will start, idle and rev, but within 10 minutes, at anything over 1/2 throttle (in nuetral or driving down the road) she stumbles (seems like runs out of gas) and dies.  Then she won't start for at least 10 minutes (cool down).  I am sure Ed is right...I likely have multiple issues.  After checking / eliminating several items suggested, including replacing the coil, I'm beginning to think the primary problem is heat related. (Viv made some very interesting comments on the subject previously)

 

Does anyone have a suggestion as to how to eliminate (disconnect) the heat exchanger tying the Johnson to the exhaust manifolds?

My fan belt is pretty lose to, hard to watch from inside the car...maybe that's aggravating things.

I wonder if I can get any clues by using an infrared thermometer...I'm now realizing my temp gauge does not work.  Any rebuilders out there?

 

Thanks so much for any help, I'm amazed at the generosity of time & knowledge.

Lew

[m-mman]

37 minutes ago, LewUnderCar said:

Does anyone have a suggestion as to how to eliminate (disconnect) the heat exchanger tying the Johnson to the exhaust manifolds?

Each exhaust manifold has an opening (2 bolts) that connect it to the intake manifold. Part of the exhaust flow passes through the intake manifold. This passage can be seen in the picture you posted. 

 

The amount of exhaust flow is increased/decreased by a flap near where the 2 manifolds join and is/was controlled by a lever on the dash. Quite possible that this is not functional OR the flap could be stuck closed(?) which would really heat things up. 

 

In any event the procedure is to (simply) remove the bolts that are holding the crossover tube to each exhaust manifold, create a solid piece of metal that will "slip" into the connection blocking the flow of exhaust and then tighten everything up.  Uhhhhh. . . . . yeah. . . . . .right. . . 

 

To accomplish this and work through the inevitable stuck exhaust bolts and broken exhaust bolts and slide the crossover tube back into the intake manifold slightly (the distance of the blocking plate - it has a large compression nut that you will not be able to remove) will take removing the intake and both exhaust manifolds and then test fitting and re-gasketing to get everything functional again. 

Typical simple old car repair that can become a big, but necessary, project.

[LewUnderCar]

Thank you for that very helpful explanation...I checked the two tubes with an infrared thermometer tonight with the engine at idle and was surprised that one crossover tube was 450F and the other was 220F (the exhaust manifolds read 450F.)  This is probably another dumb question, but am I correct in understanding that I will install my blocking "plates" at both sides where the tubes enter the exhaust manifolds?  (like making a gasket with no hole in it for both flanges?)  I can't wait to start twisting on those old corroded bolts...I imagine, if like every other thing it touch, this will indeed turn into a "big project" as you say. (maybe I can just fill in the tubes with JB Weld....ok just kidding.  Maybe my wife's cornbread batter?)

[LewUnderCar]

After further inspection trying to find a "flap near where the 2 manifolds join and is/was controlled by a lever on the dash" I see only the item in the photos attached, which located toward the front of the left exhaust manifold.  I found a drawing in the "Shop Manual" describing the heat/spring actuated valve.  I bet it is stuck which would correlate to the high temp of the left hand side exhaust passage. All these weeks searching through manuals about the carburetor, I never thought about the exhaust manifold having a valve so far from the carb!  I've been preaching "Never assume anything" for so long I forgot to take my own advice. 

[ipeeforward]

On 1/3/2022 at 1:54 AM, LewUnderCar said:

Thank you very much...greatly appreciated information & guidance.   I checked the compression today and all cylinders are in the 100-110 range.  I keep looking for the "Auxiliary Air Valve" lever described in several tune up documents I have for the Cadillac LaSalle 1931 carbs...I do not see it...maybe mine was replaced with some other year?  My Block number (in the 800,000's) seems to indicate it is a very early 1931 engine, which makes it odd when I try to determine what instructions to follow in my "National Service Manual", that says 1931 cars start with block numbers 900,000.

 

Still trying to figure out why my old timing light won't fire despite being powered by a separate 12V bat. and not sure if I know what to do if it does decide to fire. (I've read that old dudes like me should challenge our brains in an attempt to keep the cerebral juices flowing. Me trying to wrap my pea brain around 6V positive ground electrical circuits is more than challenging for me).

 

Re. The timing light not working,  sometimes there is not a strong enough spark to trigger the pickup. Try pulling the ignition lead from the plug by 1/8in (so you can hear it jumping the gap). 

[LewUnderCar]

Thank you.  I'll give that a try.

Lew

 

[TimFX]

Here’s my 27 Chrysler running great on a new Zenith carb. Fuel pump has been added