MGB & GT Forum

this week i had my 'B converted from the single zenith to a pair of s.u. hif-4s, along with the backdated distributor, falcon exhaust system and k&n air filters. can't wait to pick it up from the shop and try it out this weekend!



Edited 3 time(s). Last edit at 2014-04-17 07:33 AM by DiBiaso.

Your gona love it big time. Post an engine bay photo on how a US shop would do a conversion. My 78 was also a US version converted to HIF but I did it to UK home market specification. Words can not describe the difference in performance but I also worked the head to boost compression.

Congrats Ad'm, yes, you will love the difference.

Get your mechanic to familiarize you with the simple linkage and needle adjustments, but avoid further fiddling when they are adjusted correctly.

Completely rebuilt carbs done expertly should stay in tune for years, most often some other electrical, timing, valve or fuel supply problem sends the engine out of tune, but carbs are easiest to fiddle with.... leave them alone!

Post pics and one of the big grin on your face when you drive it!!

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1974 MGB GT, 18V+.030, Richard Longman head, OD, HIF4's, rebuilt 25D w/points, ALTIMAX RT43-185/70's on Minotaurs.

Some days I wish I could go back in life. Not to change anything, just to feel a few things twice.

I had the SU HS4 conversion done on my car 4 years ago and other than a minor idle speed adjustment, I haven't touched them. I've driven well over 30k miles and they still run great.

Enjoy.

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“Ideological certainty easily degenerates into an insistence upon ignorance". Daniel Patrick Moynihan

In any debate, the side which strays from civil discussion is usually the side that lacks confidence in its debate position or in the merit of their arguments. Making personal attacks on the opponents instead of staying on the subject is also a sign of weakness.

Anyone who feels compelled to respond in kind to any perceived slight is often suffering from narcissism.

Congrats, you are moving back to what the factory intended the B should be capable of

I know I am posting to a biased group but I need some input on whether I should do the same conversion or not. I currently have a ZS on the 1978 MGB. It runs, but needs a bit of work on it to adjust the choke. The car is my summer project and now that the engine is running, I haven't thought much about carb conversion until I found a HS SU carb that has been completely redone and I can get for less than $200.

My question is: should I do it?
and
what else do I need to do to the engine to make it fit?

Good for you A'dam, though it's a shame you missed the Spring. Seems it arrived on Friday and disappeared back into winter in Tues!

Tim - use the "advanced search" on this site to search for "carb conversion" or similar. You'll be able to waste a full day reading ~10 years of advice on how/when/why to ditch the ZS carb. Switching to the standard dual SU's requires the carbs (in good shape), intake manifold, exhaust manifold, and some exhaust system mods. Usually can be found used at reasonable prices, but it does all add-up. Switching to a weber carb can sometimes be a little less expensive, and still provide a big improvement. In any case, this is usually a good time to get your distributor rebuilt as well. So the "might as wells" do add up. You should probably make sure the rest of the mechanicals / car are up to snuff before leaping into these.

My 2 cents.

Bob

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Heaven: where the police are British, the chefs Italian, the mechanics German, the lovers French, all organized by the Swiss.
Hell: where the police are German, the chefs British, the mechanics French, the lovers Swiss, and it is all organized by the Italians.

What Bob said, plus you need the linkages that connect the carbs together and allow them to work correctly.

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Dave

thanks bob! we will have to meet up with albert and paul for coffee some weekend morning.

no worries about missing spring... i already got 150+ miles in before dropping it off on saturday.

good point about the price adding up. granted i did upgrade the distributor and exhaust at the same time.

curious to see how much of a difference i will notice. in addition to the zenith, the old exhaust was leaking a bit, and the ignition was badly timed. also had the rear lowering kit installed at the same time.

not much left to sort on this car... repair the dash lights and reconnect the overdrive is all that's coming to mind. rear main seal is leaking, but that will be a project for another year. i'd like to wait until it needs a clutch (not now), and can afford to have the engine compartment painted.

Well done! You're gonna love it.

Good choice. Although I personally have no experience of my 1979 having had anything but dual SU's. From all the biased descriptions about RB car Stromberg equipped I see on this forum, I can't imagine my MGB driving anything less than lively! Glad the P.O. had already done the conversion.

Keith

Especially dont stop on the side of the road in front of a government building in high alttitude in order to add fuel in the adjustments, you may be pulled "lit up by the red and blue". Happened to me.a ton of fun they are.

Did it last year on my 78. I have been very happy with the conversion. Good luck with it!

You're gonna love it.

Someone already said it, but don't fiddle with them! They're truly set and forget carburetors, no reason whatsoever to touch them once they're good. Now if you're the tinkering type like me, it's fun to mess with them, but there's really no *reason* to.

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1973 MGB: Blow through supercharged, intercooled, 10psi boost. VP12 cam, aluminum flywheel, 8.9:1 compression. Black label OD, Saab 15” minilites. Goes a lot better than it looks.