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Why the SU carb hate?

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ABfish

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My Sprite has started instantly and run well since I bought it a couple months ago, but idled rough. A spark plug reading showed that she was definitely running rich, but after seeing a lot of negative SU comments online (touchy, troublesome, takes a delicate hand to adjust, etc.), I was hesitant to start fiddling with my carbs.

Well curiosity got the better of me, and I start tinkering. Syncro, needle adjustment, another syncro and idle speed adjustment and I was done. Maybe 25 minutes, including time to read the shop manual. The idle is much smoother now, and the exhaust is much cleaner, based on my unscientific sniff test.

And, not to get too carried away, but this may be the best- starting carbureted car that I've ever owned. Pull the choke, pump the gas, and she starts.

Why the hate for these carbs? Not only do they work well, they look cool!
 
like anything else, people what love 'em, love 'em, people what like webers and other such love webers and other such. Me I loves 'em!
 
I haven't noticed much SU hate here... A bunch of ZS antipathy, perhaps! I agree that Spridgets run best on SUs; even the Stromberg ones. I always thought Weber was the cheater's way out. (And I run a Weber, so I can say that!) I love the SU design; such a simple and elegant way to regulate the mix.

You don't have to pump the gas with an SU: it has no accelerator pump.
 
The SU hate is not necessarily in the forum. More in the reviews I've read of the cars. I was convinced I'd go with a Weber until I started reading this forum. I found a couple of threads on BCF where some knowledgeable posters made a case for keeping the SU's, so I decided I'd give 'em a chance.

Don't pump the gas! No wonder it starts so well when I reach in the car and crank it while standing outside.
 
Heck they even make my Nissan 1500 sing.
A pair of HIF4's on a 1500 - hard to beat that!!
 
I'm very happy returning to SUs on my race car (after a recent engine-swap).

My '69 street MGB does not have SUs......it was converted by the previous owner.
I bought a nice, used set of HS4s and will convert it back when I have time.
 
Classic Motorsports mag did a recent comparison of Weber and SU with either a Midget or MGB on a dyno. I think there was not a lot of difference in hp or acceleration. I will have to look through magazines and find it. It is not online.

Mike
 
That was a great comparison article w/ not much difference between types.
I think SU's are simple and the owners are complicated!!!!
 
I'm of the belief that SU's AND their owners are simple!
I've got the SU's to prove it!
 
BugeyeNJ58 said:
I'm of the belief that SU's AND their owners are simple!
I've got the SU's to prove it!
Click to expand...

+1 I have an SU also.
 
I love SUs. The HIF6 that was on my BE when I bought it worked flawlessly. The HS4s I installed took some sorting to get right
but it is so easy to do I rather enjoy fooling around with needles. Simple and VERY effective carbs. Look Uber cool too.
The things came with AAMs and man those boys were rich. Great at the track but not so great on the street. I tried several different needles and settled on AAAs as a compromise.
Still they weren't the best for the street.
Yesterday I switched the AAAs for some AAEs. Much smoother on the street but at WOT they are not the gas stuffers the AAMs and AAAs were.
They are soooo easy to switch I decide to run the leaner AAEs for normal use and switch to the AAAs for track days.
I mean it only takes like 15 minutes to change needles.
Tuning Webers isn't so simple.
I've run Webers on my Land Cruisers for many years and like them
in that application but on a LBC...it's SUs baby!
 
I've a single HIF44 on my 1275 frogeye, runs like a dream, oooodles better then the original worn out twins.

Adrian
 
I think that the distrust/fear/dislike of SUs and similar comes from them being different than what folks were used to. If your normal frame of reference is a Holley 4-barrel, then twin SUs are going to seem very odd and tough to understand.

I like them, though. Twin SUs just seem right on a British sports car. Heck, the Bings on my BMW motorcycle are quite similar, so I've got some version of them on all my old machines. :smile:
 
Only reason our MGB has a DCOE on it is that the SU's were spindle-worn and I had the Weber rig on the shelf. i.e. laziness. The beast is cammed so there's some argument for the Weber as a better induction device. But a pair of SU's can be set up for that as well.

Oh, BTW, there are Webers and there are <span style="font-style: italic"><span style="font-weight: bold">real</span></span> Webers. That DFV/*** whatever is actually a Holley in sheep's clothing. :devilgrin:
 
Couple comments on the SUs, my first three or four cars had them, they (and their cousin the Zenith Stromberg) are the only carbs I really know, so I am kind of the opposite of the "don't like em cause they are strange to me, I wouldn't know where to begin to look to adjust a Holley or other typical American V-8 carbs.

As far as the carbs themselves they work pretty well, and are reliable, the main recurring problem I used to see was the float bowl needle sticking and getting gas overflow, I have not had that problem for years because I convert all my cars to Grose Jet needles, some don't like the grose jets, but they also make a modern float needle that seems to work better and solve the problem.

That being siad the other thing is that 95% of carb problems are electrical, people have ignition issues and start to fool with their carbs and mess them up.

I have never fit are had a car with webers, as I understand it you can get a very slight bit more top end out of them, but the main difference is they have an accelerator pump which basically dumps gas into the motor when you hit the throttle, good for a more instant throttle response.

I also understand, and I have talked to a lot of people who agree, that Webers are harder to set up right, but when set up right they should and usually do stay right for a long long time.

Personally I think for most people if they don't really like to tinker (or are happy paying someone else to tinker) they will not be happy with their ol LBC in the long run. I like to tinker/adjust/rebuild. Much more satisfing than just buying a new black box and plugging it in like you do on a new car.
 
glemon said:
Couple comments on the SUs, my first three or four cars had them, they (and their cousin the Zenith Stromberg)
Click to expand...

In my experience, the Zenith-Strombergs are the pretentious black sheep of the family. Difficult to get into line they think they can do whatever they want just because they are always a little rich. :smile:
 
I am runnning a weber on my Midget because the is what was on it when I got and I know them well from my pinto days (Holley 5200). The weber Italian carb has been adapted to fit about everything over the years. There is a reason some of theme Ferraris had 6 webbers on the v12s.
That being said. I had a 1972 Mercedes with twin SUs and they worked absolutely flawless with the throttle response of a motorcycle. All I ever did was put some ATF in the dashpots.
The car developed a very rare crack in the cylinder wall and started missing on one cyclinder, but even on 3 with the SUs it would run over 90mph with a 2000CC engine.
I think the only draw back to them is the same thing with twin carbed motorbikes. You have to synchonize them if you ever mess with them. I think that if a car was used regular and oil kept in the dashpots there would never be a need to mess with those carbs and they would be wonderful.
Problem with old cars that sit is that the gas gets old and plus people want to swap air cleaners and exhausts ans tinker with the carbs.
I say the Merc was the only car. I had probably a dozen different minis when I was in England and they had just the one SU and never had to touch them either. They just worked.
 
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