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MG MGB Technical - Alternative carburettor...

Hi lads!
I´ve got an MGB -70 with Lotus wrought pistones in a 1900cc engine with a modified cam. This has given my MGB about 15 bhp, wild guess. And my question is after reading a thread from this fall;
Instead of buying a Weber 45 dcoe or double 40 dcoe (by the way, which of the previous alternatives do you guys recommend? One 45 dcoe or double 40 dcoe) could I go for a cone or "open" airfilter instead? Because all it needs is to "breath" some more!
Greatful for all answers.
Ted.
Ted

Ted

I know there are some who disagree, but over 30 years trying various setups on a variety of Bs, I have never found anything but the most marginal of advantages in using any Weber for road use

The difference in power from twin HS6 SUs is no more than about 2% and there are almost always losses in tractability and fuel consumption if a Weber is used - if it is jetted correctly ( and that in itself is not easy) the deterioration in consumption is not great, but to get smooth running through the whole rpm range on a road car is not very easy

Unless you are racing, I think you are far better off using 2 HS6 SUs on a decent manifold ( Mangoletsi used to be one of the best but I have not seen one for a long time) and they also have the virtue of sounding nicer than the Weber which make a rather horrid gobbling noise except under full throttle

Another problem is that the Weber is not designed for vacuum advance and getting a suitable distributor curve is another problem

Christopher Storey
chris

Ted-
I would have to agree with Chris for all of the reasons that he listed. If you're using a five-port head on a Big Bore engine, then your best bet is a pair of either SU HS6's or, better yet, a pair of SU HIF6's. If you really want to fulfill its potential, you should seriously consider having your head reworked by Peter Burgess to his Fast Road Big Valve specification. Click on this: http://www.mgcars.org.uk/peterburgess/page9.html
Steve S.

Ted-
I forgot to add that the K&N conical airfilters won't flow enough air to feed your engine, go with a pair of K&N 6" X 3 1/4" deep airfilters and you'll have all the flow that you'll need.
Steve S.

Steve, thanks for your reply.
The K & N filters you suggested, should they be fitted without changing carburettors? What I´m trying to ask is... Does the K & N, (6"*3 1/4"), filters work together with the original SU´s?
Ted

Sorry Chris! I forgot to thank you in my last thread... Thanks!
Ted

Surprise!!!
It´s me again!
I keep remembering things I want to ask you about.
Steve, if I´m gonna buy the K & N filter you where talking about I have to buy two of them, right? One on each side?
But, the measures you gave me is measures on, lenght? Width? I´m not a genious in airfilters as you probably already know... Sorry about that, but I´m learning.
Hope you don´t mind answering that question!
Best regards, Ted.
Ted

The Mangoletsi Manifolds are listed at Pierce Manifolds. http://piercemanifolds.com/ The catalog lists a model MM 4150 for B series engine with 1-3/4 SU's. I haven't inquired as to availability.

Regards,

Peter
Peter G

Ted-
The K&N's are 6" diameter X 3 1/4" deep. Yep, you'll need a pair of them, one for each carburetor. K&N makes backing plates for both the 1 1/2" (SU HS4 and SU HIF4) and 1 3/4" carburetors (SU HS4 and SU HIF4). Don't forget to install the K&N stubstacks with them. My current engine uses the smaller of the two (HIF4's). Have you got an Email address that you can post?
Steve S.

Sure, here it comes, klasa_jh@hotmail.com
Ted

This thread was discussed between 25/01/2003 and 26/01/2003

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