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MGB Original SU vs WEBER 45 DCOE 152 Side Draft Carburetors spinning smiley sticking its tongue out

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hsisodia Avatar
hsisodia Silver Member Hersh Sisodia
East Lansing, MI, USA   USA
1970 MG MGB MkII "Esmeralda"
2005 Mini Cooper
I am thinking of changing the original SU carbs on my '70 MGB to Weber 45. Is one better over the other? Why? Please opine smiling smiley

Thanks!



Cheers!
Hersh

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Kewvet Avatar
Kewvet Barry Minster OAM
Abbotsford, Victoria, Australia   AUS
1966 MG MGB "Little Blue"
2013 Volkswagen Polo GTI "Fast FREDdy"
I'm told that the Webers will stay in tune longer - and will provide slightly more power than original SU carbies.

little red rollerskate Avatar
little red rollerskate Richard Spurling
Adelaide, South Australia, Australia   AUS
I've been told that this is one of the classically regarded ways of starting a fight hot smiley

My understanding is that for normal street use, properly tuned SUs will perform as well and be as trouble free and reliable as a properly tuned Weber.

If you're racing, the extra power from a Weber may be useful. You're not going to notice it on the road.

If you want a Weber because it's a Weber not them silly SU thingies, you are much better off getting a Weber.

If your engine is modified, all bets are off and it's a discussion to have between you and your engine builder, with whom you should have discussed how it's going to be used.

For the little it's worth, my engine is a slightly warmed up MGB motor, and she is perfectly happy with her twin HS4s.

Another classical way of starting a fight is to ask which is better, the HS4 or HIF SU carbies.
My thoughts on that are similar to the above - I had them on my GT and they were every bit as nice to live with as the HS4s I had before and have now.

Personal preference mate ... unless you have something wild under the bonnet and the engine builder recommends the Weber ... or something else.



The first rule of MG is never ever ask why - there usually is no good reason, accept it and try and work out how to mend it

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joron Avatar
joron Silver Member Michel Joron
Roxboro, Quebec, Canada   CAN
1977 MG MGB "Victoria"
Once a Weber is setup it stays setup forever, cold or hot doesn't matter the engine will start.
You just have to look if you need a new air filter once a while. You don't need to add the oil in the carbs, there is never a leak of gas.

But in your case you will need to change intake manifold to fit the big weber. If your intake manifold is not broken it won't be easy to remove after 40 years.



1977 MGB Red 'Victoria'
All Classics:
Married, 2 children, 2 dogs, MG MGB May to December.

JMoore Avatar
JMoore John Moore
Clifton Park, NY, USA   USA
I'm an SU guy, so I'm biased. I did own a 45 DCOE a few years ago, that I picked up in a lot of parts. I played with it a bit, but went back to the SU's. The great thing about a DCOE is that they are "infinitely modifiable" (with a vast aray of chokes and jets); but the bad thing about a DCOE is that they are "infiniately modifiable" and it can be costly swapping out parts until you find out what works best for you.

Like Richard says, unless your engine is hot rodded or you plan on doing some racing, I would stick with the SU's unless you really just have to have a side draft DCOE.

Oh, when I did have the DCOE, it really drank the gas! With the SU's I got around 28 MPG with good performance, the DCOE I got around 20 MPG. Then again, I might not have had it set up right!



John Moore

'70 MGB, '68 MGBGT, '99 Land Rover Discovery II, '61 Austin Healey Bugeye Sprite

FreeFallHalo Avatar
FreeFallHalo Tony D
Tracyton, Washington, USA   USA
I'm an SU person myself. I think it's a personal opinion, especially if it is a car used for pleasure.
Similar discussion is: Points and condenser V electronic ignition. What's better? Personal opinion.

Tony

If your not living on the edge, your taking up too much room.

mgbuick steve sullivan
grand junction, co, USA   USA
I have driven my 1974 mgb with a Weber 45 DCOE for about 15 years. You need about 2000 rpm to really feel the power gain. A rebuilt mgb engine with a high lift cam works great. You must get a fuel pump that can supply about 3 lbs pressure. A WEBER 45 likes to be driven fast and loud. I got 23 Mpg compared with the SU's 21 Mpg. My DCOE 45 has worked wonderful but during a long wiring project it has refused to accept fuel. A new float and jet has had no effect. I tried a weber downdraft outlaw and the mgb started right up and sounded good but I cant enjoy it yet. SU,s have a gentle nature and the weber downdraft is smooth and dependable but they are not as fun as a side draft DCOE 45.

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Brittsonly Avatar
Brittsonly Dean Hickenlooper
Darien, Illinois, USA   USA
GO FOR IT !!! cool smiley

fast-MG.com Avatar
fast-MG.com Gold Member Dave Headley
Cortez, 4 corners, Colorado, USA   USA
Hersh, lots of valid opinions expressed above. It would help if you gave us some idea as to your goals for this conversion. The 45DCOE-152s are very good carburetors, at least the ones I have worked with. The biggest factor in going with this is to get the right manifold. You want to avoid the very short runner one in favor of longer with gentle curvature in the runners. You will also need to re-curve the dizzy for running W/O vacuum advance.cool smiley



Edited 1 time(s). Last edit at 2013-12-29 11:15 AM by fast-MG.com.


Member Services:
Dave Headley, dba FAB-TEK offers full service race car parts and preperation for MGB & MGA race cars, SCCA and Vintage. Dave is a mechanical engineer and has raced MGBs since 1963.
pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, Nova Scotia, Canada   CAN
Here's a thought I haven't seen expressed in one of these threads yet... the factory must have had access to Webers as well as SUs (or any other carb). If I were a vehicle manufacturer (MG) and I had access to a carb that would do wonderful things for my product like more power, more reliability and better mileage, why on earth wouldn't I have switched over myself? Especially with a sports car where performance figures sell cars.



Home built Eaton M62 Supercharger with 9psi boost, "stock" high ratio rocker arms, 8:1 compression, Piper 270 cam, ported head, matched manifolds, CB Performance computerized ignition.

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fast-MG.com Avatar
fast-MG.com Gold Member Dave Headley
Cortez, 4 corners, Colorado, USA   USA
Adrian, I have to believe, that back in the day, cost as well as country of manufacture would have been a big factor. I think the factory racers had 45DCOE carbs.smileys with beer


Member Services:
Dave Headley, dba FAB-TEK offers full service race car parts and preperation for MGB & MGA race cars, SCCA and Vintage. Dave is a mechanical engineer and has raced MGBs since 1963.
pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, Nova Scotia, Canada   CAN
Apparently the people at Volvo were none to bright either... they used SU's... and the Japanese actually built SU's under license.(Hitachi)

Why anyone would remove a CV carb from a street car and replace it with a non CV carb is a mystery to me.



Home built Eaton M62 Supercharger with 9psi boost, "stock" high ratio rocker arms, 8:1 compression, Piper 270 cam, ported head, matched manifolds, CB Performance computerized ignition.

kendo ken b
new york, USA   USA
the su`s are great carbs. mine needed a overhaul about 15 years ago and i decided to go with the weber. i love it . . maintenance free for the most part slightly more power and i love the sound of it opening up when i dump the gas pedal !!!

FreeFallHalo Avatar
FreeFallHalo Tony D
Tracyton, Washington, USA   USA
I have a question. Who is manufacturing Weber Carbs now? It is my understanding Weber went out of business a few years back.
To me SU carbs have always been very reliable and extremely simple to tune and maintain.

Tony

If your not living on the edge, your taking up too much room.

Grahamhaber Avatar
Grahamhaber Graham Haber
Dingman Township. Pa., NYC,New York, USA   USA
Don't do it! I just switched back from a Weber 45 DCOE. I'm one of those who has had the same B since before having a drivers license now 35 years later I have lots of choices that now I am undoing. Just last year I found my old SUs in my family barn that had been left there since high school when I put on a Weber. I got the weber because as a kid there was no internet and no MGE I never really learned how to work with the SU. The weber was supposed to be easier and more power and it was the works racer choice. I rebuilt my old carbs put them back on, not expecting much. They car ran better than it ever had before. The SU is matched to the full rmp range where the Dcoe does best at the very top. Poor performance at the low end and for me always poor starting. I really love the SUs across the whole range and once I understood the carb and also switched to the spring loaded needles which take the challenge out of centering the needles I find them really easy to manage. Finally The look right under the hood.


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