What Carb?

[badvibes]

An informal poll. What do you run? Seems like I read that most don't like the Solex then it's a split 3 ways between the Zenith, Rochester and one of the Webers. What do you run/prefer and why? What are the downsides of what you run or choose not to run?

I have a Rochester. Was on the truck when I got it. Upside: supposed to make good power when set up right, decent off road, get a rebuild kit anywhere. Downside: I haven't ever been able to get better than 12-15 mpg no matter how I tune it or drive it.

Sorry diesel guys you don't get to play.....

[bmohan55]

Exact same story as you, Rochester from PO, fairly problem free but thirsty.

[thixon]

Hell I have the rochester that was originally on my truck. Engine is now built up with a brand new weber. It aint on the roat yet, but I'll be interested to hear how this thread goes. Should I rebuild the rochester?

[SeriesShorty]

I had the Weber when I got my truck. Ran like crap all the time, couldn't get above 35mph very easily. Super sensitive to dirty fuel.

I got a Rochester and rebuilt it and instantly noticed a performance improvement in that I was able to hit 45mph with no problems. Other than the fact that I can't seem to stop a faint fuel leak, and a bit higher gas consumption, I love it. My Disco was only getting 9mpg, so even lowering to around 13mpg with the Rochester switch it's still good gas mileage to me!

[siii8873]

I have two SIII's with two different carbs. Thing 1 is a 7:1, standard ignition, and an original Zenith which I rebuilt. The truck runs OK but took some time to get it that way. Seems a little lacking in power on hills. Not sure of the fuel economy.
Thing 2 is an 8:1, performance cam, electronic ignition and weber 2bb progressive carb. Truck runs very good, good power and gets about 20mpg. I have only had this one about a month.
Not fair to compare the two as they are very different. Either of them are acceptable to me as good running trucks.
The thing 1 and thing2 is what my wife named the rovers. When we would take a rover she always says "we're taking that thing". Quite a compliment in my eye.

[thixon]

Okay, since you brought up the weber 2bbl, as it turns out I have one lying around that I never used (actually, I have lots of stuff lying around that ive never used...sad really) It was bought for an MG, but never got installed. I believe its the same carb.

Anyway, I always heard they were'nt worth the trouble, and did'nt make much more power on a rover, and that the mileage was worse than a single. Sounds like I may have been misinformed. Where do you get the manifold for this carb?

[siii8873]

The carb came with the truck. From the receipts it was purchased with the carb from the "British Northwest Land Rover Co" I think that Pierce Manifold also has carbs and manifolds for fitting these to series rovers.
I like this setup so far. I have test driven a number of rovers while shopping for one and this one was the best runner of the group. Again it does have the 8:1 head and a performance cam.
Bob

[scott]

Okay, since you brought up the weber 2bbl, as it turns out I have one lying around that I never used (actually, I have lots of stuff lying around that ive never used...sad really) It was bought for an MG, but never got installed. I believe its the same carb.

Anyway, I always heard they were'nt worth the trouble, and did'nt make much more power on a rover, and that the mileage was worse than a single. Sounds like I may have been misinformed. Where do you get the manifold for this carb?

thix i have the weber 32/36 dgv and a standard manifold. it's not the best set up but with a 2.5 cam and a 1 3/4" exhaust and some shade tree engineering of the linkage i've been able to get it to run very nicely. i see the pierce manifolds on ebay every now and then and some original 2brl manifolds on ebay uk but just can't seem to sneak enough out of the wife's purse to get one.

[gudjeon]

Zenith every time for me. Once you figure them out and get past all the bad info on them, they are great. Dead simple to rebuild and simple to diagnose problems with. I have one on my 7:1 2.25, ser1 88". No o/d at 60mph can get 22mpg in US gal. (Imperial gal is 24mpg)

[siiirhd88]

I currently run a Rochester on the 109. It has been the most trouble free compared to the 1V Weber and 1V Zenith. I'm getting 11 mpg on winter blend fuel but was getting 13 mpg last fall when I first installed it. I do know this Rochester needs a smaller jet, as the plugs are dark brown.

The Weber 1V seemed to have more than adequate power and was getting 17 mpg. The Weber was having continuous idle issues due to dirt in the fuel, in spite of multiple filters. I never knew if it would idle fine or just die off one stop to the next.

The Zenith carb was always leaking and frequently required adjustments. I replaced it with a brand new Zenith, and did all of the required fixes, but the new one still leaked and also needed frequent adjustments.

I have a used progressive Weber 2V from a 4 cylinder Jeep that I am going to try on the original manifold as soon as I have the opportunity.

Bob

[LR Max]

I've run three carbs:

Zenith = crap. Never could get the stupid thing adjusted worth a crap and was just crap in general.

Weber 34ICH (one barrel). Friggen bullet proof and goes forever. Bestest off road carb hands down. Always ran and kept going. However I never felt like I got the most power with it.

Rochester: Preferred and what I recommend. Put in the correct jet and roll with it. It works and provides A LOT more power than either of the ones listed above. For off road, put some 1/4" fuel line on the vent tube at the top of the mouth of the carb. When you get off camber/climbing/descending, the carb will keep working. I couldn't tell a difference but after the modification, a number of people told me that the engine "just sounded better".

As a second reason to run the rochester: When it craps out, just take it to NAPA (ONLY NAPA!!) and exchange it. Done. No fiddle farting around and don't bother trying to rebuild it. Tried a few times with instant fail. Besides, the exchanged one is about $40 bucks more than a rebuild kit.

[Rineheitzgabot]

I have a Weber with a Pierce manifold. I absolutely love the performance. Never falters. It gets about 18 mpg, on perfectly level, concrete, that has been smoothed like a garage floor, and is long enough for me to reach 55 mph, with a slight back-wind. :)

Seriously, does anyone ever get more than 15 mph in their Series?

We're driving Land Rovers, folks. We should seriously consider another mode of transport if mileage is of any concern.

I would be interested if people have ever measured their mpg, in a reliable method, that I can compare mine with, for curiosity.

[ybt502r]

Zenith for me. I had a Weber when I got the truck, and the mileage was sad and performance ditto. I found a new (in the original box) Zenith in the UK, installed it, and had an immediate improvement in economy and performance both. Eventually I moved with the truck to Colorado, where it ran rich (8000 ft altitude).

Moved with the truck to Calgary, Canada. Warped the carb on the drive (the basic problem with some Zeniths), reground and rebuilt it, and then killed the carb by breaking off the idle screw tip inside the carb body. I did find a rebuilt Zenith (already un-warped), changed out the basic jet for a high altitude jet, and it runs sweet. Installed Pertronix, and the whole thing runs solid with very little need to adjust. I would not go back to a Weber; don't know about the Rochester; but the (original) Zenith is simple, steady, and works. Mileage is 15+ and around 20 on freeways (which I don't see much of).

[JimCT]

Remember a gallon is different in different places.....

[jgkmmoore]

For a different perspective...I'm running an SU. Believe it's an HS series, but unsure what size. It's a trooper. I have a tired ol' engine, but it still has fairly good power. Couple friends running Webers and one with a Rochester, have driven my 109, and are reasonably impressed with the power, and the lack of cold bloodedness. I just bought the truck about 9 months ago, and it had a nasty running engine. Took it to a local guy that is GOOD with SU carbs, and within a hour and 1/2 he had it running like a Rolls.Sweet idle, excellent acceleration,better upper end power than other carbs me buds had (by their remarks). Instant starting, with about 5 seconds of choke after start, then drive off. Not cold blooded at all. The plugs remain perfectly, evenly tan with no electrode wear. Claims to be excellent off camber for sidehilling and steep climbing either backward or forward...never stumbles. 16-21 mpg so far. I can ignore it. Dirt doesn't seem to upset it. K&N filter makes it sound like a 4 bbl when you accelerate(if you can call it that). Haven't timed it 0-60 yet, haven't made it to 60 very often. Too scary. It's less than 5 minutes tho.
The guy that slicked it up for me, told me to leave it alone, and concentrate on ignition first, whenever uneven running occurs. He sez to resist the urge to screw with it at all because it's the least likely thing to go awry once set up right. Me buds with the Webers complained that they were cranky about dust/dirt, and off camber driving. The Rochester guy liked his just fine...got it off a '54 Chevy truck 6 cyl. $20.:D:D
If someone offers you an SU for free, DON'T turn it down. Good carbs. Oft used in multiples....easy to sync.(Jags,MG's,Triumphs,etc).

[TeriAnn]

I suggest that folks with after market carbs who haven't already done so find a place where they will stick an O2 sensor up your tail pipe and just give you an air to fuel ratio number. Knowing what it is allows you to dial in a main jet for best fuel mileage. These carbs often are jetted wrong for the Land Rover engine.

There are a lot of things that affect fuel mileage on a LR. Such as weight, tyre type, top or no top, altitude, where you drive and how your right foot treats the pedal. Most hard top LRs with the right air fuel mixture seem to get around 15-16 US MPG on the open highway and 7-9 MPG stop and go driving. If you plug the 2.25L's numbers into an engine volumetric efficiency formula you will get a flow rate of 128.6621 CFM at 4250 RPM, the max. rated power for the 2.25 engine.

Here are some numbers from the formula:
engine RPM - CFM
2000 - 64.6
2500 - 80.7 (peak torque)
3000 - 96.7
3500 - 105.9
4000 - 121.1
4250 - 128.7 (peak HP)

Tests performed by Jim Allan showed that the oil bath filter with its 90 degree adapter becomes more restrictive with increased air demand and "pretty much falls on its face by 3800 RPM" Its great for getting the particles out of the air going into your engine and suitable for regular driving below about 3500 RPM. On the other hand a K&N will breath freely through the engine's RPM range but does a lousy job of cleaning the air. OK for highway use but maybe not the best choice off the pavement. Some people carry both and switch between them depending upon where they drive.

A quick note about air flow & the smaller venturi carbs: a carb with a smaller venturi will normally produce more torque at a lower/mid rpm range because the velocity of the air/fuel mixture through the venturi will be higher and you get better fuel atomization and better combustion. Air flow testing referenced below was done by Jim Allen close to sea level. With that in mind:

The Solex flows 115CFM @ 1.5" of mercury. Traditionally the Solex is an excellent carb for trail driving and works very well at lower RPMs. But it is more restrictive than the other carbs at freeway speeds.

The factory Zenith flows 127CFM @ 1.5" mercury. Traditionally the Zenith is a good performer across the RPM range and a smooth running carb. It is usually considered the best choice for a 7:1 engine and a good choice for a stock 8:1 engine. It is a little flat at peak HP RPMs but few people ever drive there.

Rochester B carbs comes in different venturi sizes. You want the one that came on the smallest Chevy inline six. It flows 167CFM @ 1.5" mercury which is enough to handle the entire RPM range of a 2.25L engine. It is a very simple carb with a centre float that works well at high off road angles. The main jet is at the top of the fuel bowl so a little crud in the bottom of the bowl doesn't affect it.

Weber 34-ICH carbs usually sold for use with LRs are a generic replacement carb. They often come jetted too lean for the LR engine. When they do people report really good fuel mileage but tend to burn a valve or piston from running too lean. If you are getting better than 16 MPG highway on one have your air to fuel ratio checked to make sure it is jetted correctly. Different versions of this carb can have different flow ratings. One commonly found on LR engines flows 138CFM @ 1.5" of mercury. The Webers can often develop problems from crud getting past the fuel filter. Its main jet is at the bottom of the float chamber where it is easily clogged by particulate matter. So a good fuel filter, replaced often is essential for keeping these carbs trouble free.

The 2.5L engine came from the factory with a 32/34-DMTL progressive 2 barrel Weber. Unfortunately this is a discontinued carb & is hard to find in the US. Venturi sizes are 26/27 mm. This carb flows 194CFM @ 1.5" of mercury. This carb was coupled with an additional quarter liter displacement and the 2.5L cam with 8:1 head. It is usually considered a good choice for a performance rebuilt 2.25 engine. But the carb is hard to come by unless you buy a complete 2.5 engine.

The 38-DGAS 36/36 Weber commonly sold in the US for use on a LR is flow rated at 424CFM @ 1.5" of mercury and is way too much carb for the engine. Its venturi size is 36/36mm.

Another 2 barrel carb often sold in the US for LRs is the Weber 28/36-DCD. Its venturis are 26/27 MM. Its flow rate is 224CFM @ 1.5" of mercury. This is still way more than a 2.25L can handle, but some people have been able to jet it down well enough that it works on a LR engine.

My thoughts are that for a stock engine staying with the stock carb is always a good choice as long as it is running within spec. If you feel a need for an aftermarket carb, the Rochester B series that came on the small Chevy six and the generic replacement Weber 34-ICH are both good choices so long as they are jetted properly. The Rochester often comes over jetted and the Weber often comes under jetted. You really want to have the air fuel ratio tested to get the jetting right.

[scott]

...Weber 34-ICH carbs usually sold for use with LRs are a generic replacement carb. They often come jetted too lean for the LR engine. When they do people report really good fuel mileage but tend to burn a valve or piston from running too lean. If you are getting better than 16 MPG highway on one have your air to fuel ratio checked to make sure it is jetted correctly. Different versions of this carb can have different flow ratings. One commonly found on LR engines flows 138CFM @ 1.5" of mercury. The Webers can often develop problems from crud getting past the fuel filter. Its main jet is at the bottom of the float chamber where it is easily clogged by particulate matter. So a good fuel filter, replaced often is essential for keeping these carbs trouble free.

The 2.5L engine came from the factory with a 32/34-DMTL progressive 2 barrel Weber. Unfortunately this is a discontinued carb & is hard to find in the US. Venturi sizes are 26/27 mm. This carb flows 194CFM @ 1.5" of mercury. This carb was coupled with an additional quarter liter displacement and the 2.5L cam with 8:1 head. It is usually considered a good choice for a performance rebuilt 2.25 engine. But the carb is hard to come by unless you buy a complete 2.5 engine.

The 38-DGAS 36/36 Weber commonly sold in the US for use on a LR is flow rated at 424CFM @ 1.5" of mercury and is way too much carb for the engine. Its venturi size is 36/36mm.

Another 2 barrel carb often sold in the US for LRs is the Weber 28/36-DCD. Its venturis are 26/27 MM. Its flow rate is 224CFM @ 1.5" of mercury. This is still way more than a 2.25L can handle, but some people have been able to jet it down well enough that it works on a LR engine.
....

terriann

a lot of good dope on the webers, thanks. can you tell me where the 32/36 DGEV fits in? reading from redlineweber.com i'm wonder if it's not close to the 32/34 DMTL. the 32/36 DGEV isn't that rare here in the states

[LR Max]

Weber 34-ICH carbs usually sold for use with LRs are a generic replacement carb. They often come jetted too lean for the LR engine. When they do people report really good fuel mileage but tend to burn a valve or piston from running too lean. If you are getting better than 16 MPG highway on one have your air to fuel ratio checked to make sure it is jetted correctly. Different versions of this carb can have different flow ratings. One commonly found on LR engines flows 138CFM @ 1.5" of mercury. The Webers can often develop problems from crud getting past the fuel filter. Its main jet is at the bottom of the float chamber where it is easily clogged by particulate matter. So a good fuel filter, replaced often is essential for keeping these carbs trouble free.

Funny, mine came outta the box WAY too rich. But replacing the jets in this carb is super easy.

Yes, junk will get clogged in this carb easily. However wal-mart sells a generic FRAM filter that is THE BEES KNEES. I just replaced mine after a good solid 6 years of service. Really helps keep any carb clean. Put right before the carb and you are good to go.

Thanks for posting up the CFM requirements of the engine. If I could find my "engine calculations" book I could've figured it out but having you tell me is 500x easier :D. My current K&N is too small and actually restricts airflow on the interstate. But I noticed the big K&Ns at Advance auto are only $35 so I'll be switching over to one of those here directly.

[TeriAnn]

Thanks for posting up the CFM requirements of the engine. If I could find my "engine calculations" book I could've figured it out but having you tell me is 500x easier

I had to make use of the formula when I chose an air filter and pre-filter to put on my Land Rover. When I converted my engine over to EFI I decided that my poor engine had eaten too much dust from not being the lead vehicle in off road convoys. I ran the formula on my engine to get the flow parameters so I could go through the Donaldson catalogue to find a filter and prefilter that best met my engine and my normal driving RPM range. So like everything else I've had to research for my truck I keep the formula handy in my Land Rover web site for easy quick reference.


http://www.expeditionlandrover.info/200%20tdi%20conv%20jpegs/cfmFormula.gif

I ended up with a Donaldson filter mounted to the underside of my right wing top and a prefilter that was a direct 6 inch run into the filter intake. One thing I wanted to do was minimize changes in air flow direction.


http://www.expeditionlandrover.info/GRdetailPics/NewWing.jpg

In the picture above you can see the very bottom of the air filter along the top of the wing opening. The prefilter is a straight run into the filter intake. The filter out is at the rear of the filter aimed directly into the engine bay.

For those of you who are interested, the outer wing panel is from an early Defender that came without wing side lights, the tyres are 33.3 inches in dia on Disco I steel wheels. I was going to convert to 35 inch tyres but decided that the 33's were as tall as I could go and still easily step into my truck. With 35's I would have to climb in. My truck is also a daily driver and having to climb into a truck in a dress struck me as too unlady like. Unless the skirt is full it would mean hiking my skirt up to about mid thigh. So 33's it is for fashion and modesty's sake. Oh and the vehicle colour is British racing green.

[widerberg]

I don't know that I prefer it, necessarily, as I haven't tried any others, but my recently-bought SIII came with a Weber 34 ICH. Most of the sources I've found say this offers less power but better fuel consumption than the Zenith; but I've read in some of the Brit classic car mags that they're pretty highly regarded. So, who knows? (Incidentally, they're apparently used on performance air-cooled beetles, too).

[utahseries]

Thanks for that great load of Info TeriAnn! Now this question is more directed to the series 1 owners who have switched over to the 2.25, what carbs will give you the necessary clearance under the hood? I really want to run a rochester b, but I'm not sure if it will fit.

[1961 109 WAGON]

after trying a zenith on my 88, i stuck witht the stock solex. i have one on my 109, and with 97, 000 miles, it has never been rebuilt or leak. i have solex on both my rides.

[gudjeon]

I went with the Zenith under the hood of my ser1 with the 2.25 as it has the lowest profile I have found and I have had good luck with them.
http://i35.photobucket.com/albums/d187/gudjeon/fuelpump1-1.jpg
It is kinda crude, but it works. I have seen old motors made with a more restrictive set up than this. I made it wide to make up for volume due to a lower profile. Electrical conduit tubing and sheet metal. I kept the ser1 air cleaner. 24 Imp mpg on the highway, so it can't be restrictive. Rubber plumbing connector used for cast iron piping from the hardware store. Cheap and cheerful:thumb-up:

[Wander]

In relation to my thread on petrol smell-my IIa can with the 1v Weber-I don't know if it's been rejetted or not. I am getting a strong petrol smell after running her that smells like unspent fuel in the carb or a leak. I can't find a leak anywhere and another person mentioned the same problems with his. I've heard that running a return line from the filter helps but now I'm thinking maybe a Rochester would be a better idea overall.

I've got a low pressure e-pump with a pre-filter and another filter just before the carb supplying the flow.

I'm also getting some dieseling and lugging which indicates to me the timing is off.

[rosims]

I hate to beat a dead horse to death, but I am wanting to put a Rochester on my 109. I have a carburator, but the tag is missing on it and do not know which engine it came on. does anyone know how to tell the difference or have a measurement for the venturi size? How can you tell which one is the smallest one? I am going to rebuild it and put it on and see what happens. I have the #50 jet and a carb kit, for $20 , it's worth the try.

[TeriAnn]

I hate to beat a dead horse to death, but I am wanting to put a Rochester on my 109. I have a carburator, but the tag is missing on it and do not know which engine it came on. does anyone know how to tell the difference or have a measurement for the venturi size? How can you tell which one is the smallest one? I am going to rebuild it and put it on and see what happens. I have the #50 jet and a carb kit, for $20 , it's worth the try.

The best Rochester has a 31m venturi diameter. I never found a good way to accurately measure the venturi diameter.

A #50 jet is a good place to start but the best main jet size is dependent upon which Rochester you have and the altitude you usually drive at. You really need to get a sniffer up the tail pipe to dial in the best jet for fuel economy that doesn't under jet the engine.

[rosims]

I have a 5 main 2.25 and on the intake there is a sleeve on the intake along with a spacer. It origianlly has a weber with the adapter. When I put this rochester on it, should this sleeve be removed? With the spacer on there and the thick carb gasket, the slot for the vacum port is still partially blocked by the sleeve. would this effect the carb performance, It has a terrible flat spot in it.

[siii8873]

what should the sniffer readings be for optimal performance?

[Sputnicker]

I have the metal sleeve in my intake manifold, but I also have the phenolic spacer which puts the carburetor flange well above the metal sleeve. I'm not sure if it would matter whether you removed the sleeve, or added the phenolic spacer, but blocking that vacuum path with the metal sleeve would definitely screw up the function of the Rochester B. TeriAnn has a great write-up on her website and here is a manual for the Rochester B, which should help:

http://www.oldcarmanualproject.com/manuals/Carbs/Rochester/B/index.htm

[73series88]

i use the Weber 34 ICH.
seems to be pretty trouble free other than cleaning out the jets every so often. i havent had others to compare.
now if i could get su's like the ones on my mga.
aaron

[TeriAnn]

now if i could get su's like the ones on my mga.


Funny you should mention that. Last time I had my 2.25L engine out for a rebuild I offered up a Triumph TR3 intake manifold. Low and behold the ports matched up and some of the mounting holes did as well. I still think that a little clever machine work for the mounting studs & one could have dual SUs on a 2.25L engine.

The gotcha is that the steering box would be in the way of the rear carb for a LHD LR.

Put dual SUs on, headers and polish that valve cover (they look really nice polished) and you have an entirely different looking engine. Kick it up to 9:1 compression, put in a 2.5L cam, a distributor with a more performance oriented cam and you might approach the HP of a stock 2.5L LR engine.

On the other hand, if a stock TR3 intake manifold matches up one could always try DCOE intake manifolds for a TR3 and put duel DCOE carbs on the old Landie. DCOEs would be a poor choice for off road but they ould sure look wicked.

[rosims]

I have a 5 Main bearing metric engine and the sleeve sticks up about 1/2 inch higher than on my spare 3 main bearing earlier spare engine. That's the main difference that I can see. BTW, the sleeve is coming out this weekend, I don't see any need for it.