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MG MGB Technical - Conversion from ZS to SU's

Gentlemen (and ladies),
I hate to revisit this issue as there is so much information in this BBS about this issue, but that is the problem. I have just spent 2 hours searching the BBS and have not found the exact information I am looking for. Help please. My 77 B let me down this weekend while I was rigged in full Scottish dress at the Stone Mountaint Highland Games in Georgia USA. To cut a long story short, the catalytic converter separated from the exhaust manifold (cannot find brass nuts to secure it properly) and the water choke separated from that *&^%$# ZS Carb. After numerous attempts to set this combination correctly I have decided to spent the money and do it right by replacing the whole magilla with the SU HI4 conversion. (Carbs, air filters {K & G I think is the correct replacement}, intake manifold, headers (I can get away with emissions in GA for pre 1978)
and whatever it takes.

My question is, What are ALL of the pieces that I need to perform this conversion, and where in the USA (preferably Southeast) can I find the bits?
Does anyone know if Matthew's Foreign Car Parts in Birmingham AL have everything?

Thanks for your help, gents (and ladies)

Bob
Bob Anderson

I converted my 76 from ZS to SUs last winter --would suggest you use HS4s --I bought mine on ebay as a complete set and rebuilt them myself --have put 10k miles on the car this summer with no probs.If you dont want to do rebuild yourself there are several good rebuilders around. Ialso bought the exhaust manifold on ebay --the inlet came with the carbs--hope this helps somewhat--good luck its worth the change--Gil
Gil Price

Have done the conversion in the past also...though I disagree with Gil about the type carb to use..but, that's just personal preference...I suggest the HIF-4 with the integrated fuel bowl...using carbs with external fuel bowls can lead to real trouble when the rear carb's fuel bowl hits the brake booster (its real close & as the engine rotates under power, it will hit!) & breaks sending fuel all over the engine compartment....find a '74-1/2 car & remove everything from it (to include all accelerator cable bracketry--its different)...you'll also need to get a set of the offset conical K&N filters so you'll get enough air to the carbs without the rear air filter hitting the brake booster.
Tony Barnhill

Hi Bob, I converted my 79B to pre 74 exhaust and a Weber 32/36 DGV last year. It's not quite the same as the conversion you are talking about but it was pretty painless. As for parts try ebay, Atlanta Imported Auto Parts (404)299-5775 or Barry Rosenberg at Stillwater Services (770)459-5282. The emissions for a 77 are no problem, you don’t have to take the test after your car is 25 years old just go to the tag office and give them $25 and you'll get a cool antique tag. Just for the record though my 79 passes emissions with no cat, air pump or any other smog related equipment. I have to bluff my way through the visual inspection but on the dyno I'm clean as a whistle.
If you need any more help feel free to email me.

Eric

Eric, My 77 was clean, too, with a weber dgv, cam, and other hop-up mods... no cat. Still clean.

Personally, I don't hate emissions per se. Gives you a good idea of your state of tune. A car in good shape SHOULD pass.
Now the visual inspection never ceased to be a pain in my rear.
Baxter

Bob,
I feel your pain on the ZS. I have a set of HIF's and manifolds you can have. I sent you an E-mail.

John
J Arthurs

Thanks everyone,
John, I replied to your email
Bob Anderson

For what it's worth. My cat separated as did yours. Solution was to purchase a '75 exhaust pipe from Brit-Tek which bypasses the cat. Also did away with the muffler and replaced it with a straight pipe. The resonator at the rear remains. Performance is somewhat better although it runs lean and will require the needle from the '75 for the ZS carb.

The ZS carb is really quite reliable once it is understood. Suggest you visit Rich Jaskowiak's web site for clear pictures of the mysterious bugger.
http://uslink.net/~jasko/choke/ZSchoke.htm
At least I think that is the correct URL.

The new exhaust pipe was only $25 and fit perfectly.
jim mindy

I made the conversion this summer to HIF-4's and purchaced the entire package, including gaskets and cables, from mechspec in England - $130, without shipping. Great deal. Just remind them that you have a lefthand drive so you get the correct length throttle cable! Car runs great. Let me know if you need pictures or have any questions.
Randy Olson
1977 MGB
randy olson

Lotsa stuff on e-bay man

Cec
Cec

Jim, et al:
Rich's website has a new URL: http://personalpages.tds.net/~jasko/choke/ZSchoke.htm Same good info, same insight.

Please take a look in this BBS's archives for info on the ZS carb, especially those threads from about 1998~2001. You might not have to remove it or you may find that there are well thought out alternatives, like the HIF-4 conversion. Remember, tho the HS-4 is a good carb setup, its HIF-4 successor had the advantage of a fresh sheet of paper on the drawing board. The engineering staff at BLMC had some keen insights into what they were doing.
Bob Muenchausen

This thread was discussed between 23/10/2002 and 30/10/2002

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This thread is from the archive. The Live MG MGB Technical BBS is active now.