Silly engine questions that i'm sure could be found in a FAQ somewhere....

[Baxter]

It depends. Read this and decide for yourself.
https://shadetreemg.com/carb_choices.htm

That said, most any carb change is probably the single best thing you can do for RB performance. The single ZS, coupled with that lousy manifold, sucked almost 30 hp out of the engine.

As for headers, Peco makes the only ones that have shown to be more effective than the stock CB manifold, which is cheap and tough.

[ 04-14-2004: Message edited by: Baxter ]</p>

 

[ICESWH]

Hello and welcome. I have an 80 MGB. It had a Webber on it when I bought the car 2 years ago. It ran like a dog. Just after I bought it I had a twin SU setup put on by my mechanic, HS4 carbs. He did a much nicer job then I could have. I couldn't believe the performance difference. I would never go back. Yes, the SU setup appears a little more intimidating at first. But they aren't really that bad to work on. Also, when I open the hood it now looks like an MG. The webber just didn't look right.
As for exhaust? I swear by the Peco big bore exhaust with header. And now it's also available in stainless. The exhaust I have is not stainless, but I know Brit-Tek carries the Peco Stainless setup. I would go that route if I had it to do over.
Th other thing I would consider while it's all apart. Maybe get the headers, if not stainless, Jethot coated. I would also send the heatshield out for coating.
Good luck.
Scott

 

[Black MX-5]

Wow. Nice! That's another website to bookmark! You guys are great!

I like the twin SU carb setup. However, the websites i've been too to look into ordering them are a bit confusing. They have 4-5 different HS-4 carbs listed on the Moss site. How do I know which I want??

In order to go from the stock ZS carb to the twin SU ones, what parts do I need to replace?

Do any of the aftermarket companies offer a package deal that includes everything, or is it generally a build your own kinda thing??

Oh, and I'm sold on the Peco exhaust stuff. Is their catback as nice as the header, or do you recommend a different brand for that?

edit: I found a kit, that comes with a Weber 38 DGV carb and a Peco Header.

https://www.brittek.com/weberoutlawkit.html

Thoughts on this one? According to the carb-faq it could be decent, and easy (which at my stage in carb knowledge would be a big plus....)

[ 04-14-2004: Message edited by: Black MX-5 ]</p>

 

[Baxter]

OK, if it were me, and remember, this is just me, and my answer might not be right for you...

Carb: Twin SUs or 38/38 Weber DGES, depending on the better deal. If buying new, that'd be probably be the weber. If buying used/rebuilt, probably the SUs. Personally, I kinda like HIFs, but get what you want.

Either way, you'll need the appropriate manifold, and with the SUs you'll want the heat shield. With the weber, make sure it has all the linkage bits and all that.

That takes care of intake. On the exhaust side, if it were me, I'd use the stock CB manifold, as it works very well and never breaks. If I had money to burn, I'd go with the peco header.

If local laws require, I'd put a universal fit cat underneath, and from there I'd run 2" pipe to whatever muffler struck my fancy. Maybe a dynaflow or something.

That would bump you into the roughly 100hp range, a small increase over CB, a big increase over RB.

 

[William]

Definitely check local emissions regs. I think that in California, apparently it's an immediate fail if you swap the Stromberg to a Weber or whatever. I dunno what the regs are in Philly, but it's worth a check before you do any buying. As for carbs, I've recently discovered that SUs are pretty easy to rebuild, so if you could get a pair of used ones, it could be cheaper than new. Webers just look complex to me...if very cool when bolted to the engine.

-Wm.

 

[Guest]

Thanks for the compliment on my website. If I were gonna recarb a 75, I'd get the outlaw and a peco header, then if emissions inspection weren't a consideration, I'd cut the rest of the exhaust off and take it to a good local independent muffler shop and have them run me an exhaust with a turbo muffler. get them to use aluminized pipe and it'll last almost forever. I'd have to disagree with Baxter, 1 1/2" is big enough for a basically stock B,, you won't see any performance gains til high RPM and it might affect the lower end. BTW, tell them it is a 74 which didn't have a cat so they won't want to put one back on, unless, of course, you get inspected

 

[Baxter]

Chuck, yer right about the 1 1/2. I was thinking about my '77, which had enough motor for the 2-incher. Or you could split the difference and get 1 3/4.

Also, nobody's mentioned, if you use a stock manifold, you'll need to pick up the downpipe, too. No big deal there.

 

[Guest]

Doggone, Baxter, I really thought you and I could get up a good arguement about this, then you have to go and agree with me. I'm thinking about 2" for my v6 but then I'm gonna run a sneaky single exhaust

 

[Matthew E. Herd]

Where in philly do you live? I live Nort/Northwest about 40 miles in chester county. I can tell you for a fact that the MGB will fail emissions if you do not have a cat on it and a stock intake. (although some shops may not know the difference between the stock ZS and a dual SU setup). However, it will fail if they obey the letter of the law. My brother's MGB does not pass and is driven less than 5000 miles a year (at least that's what the odometer says ... we haven't done anything to it yet, but will if we must). It's a 1980, so it doesn't qualify for antique until next year. It had to pass originally to be registered in our name, but will no longer have to pass. However, it didn't pass on its own and required extensive fiddling. If you are going to make mods, you need to retain a cat, and wait until you register it (and inspect it for the first time) before making major changes to the intake. Once its been registered, you can probably get away with changing the intake, but will never be able to pass, regardless of mileage, without a cat because it will fail on sight.

Oh, about the above, 5000 miles is the necessary mileage exemption, which is why we limit the mileage on the MGB to that number. That just means it only has to pass visual inspection, not the running emissions test.

Ok, on to the subject of antiques (like my midget). Mine is pre-cat, however, if it was catalytic converted originally, it would never need to pass because it is registered as an antique. In PA, classic cars are emissions exempt (15 years) and antiques are emissions and inspection exempt (25 years old). However, this does curtail your driving abilities. If its only a fun car, register it as an antique and have fun. If you plan on driving it more than 3X per week, you really couldn't get away with antique registration.

I spent the past summer working for my mechanic, so I learned considerable information on PA state inspection above and beyond that which I learned in order to register my antique. Some emissions shops are stricter than others, and some won't even know the difference between a SU and ZS carb setup. I'm sure that you can get someone to pass it, cat or not, but of course, it isn't technically legal without a cat or the original carbs.

[ 04-14-2004: Message edited by: Matthew E. Herd ]</p>

 

[Baxter]

It really varies. Arizona has a fairly tough emissions inspection, but my 77, with a cam, headers, weber, high-compression, the works, always passed super clean. I lied through my teeth on the visual (yeah, that's the EGR valve!) and counted on the fact that it was in tip-top shape to carry me through the sniffer. Always worked. that one used a universal 2" cat aft of the headers, then straight pipe back to a single baby turbo muffler.

Here in Kansas and Missouri, they don't check 'em at all for emissions, and even the safety inspection is only cursory.

 

[Black MX-5]

So I was reading the '74 MGB' post and saw some of the things regarding engine differences and performance options.

I have a 75, and IIRC, it has the one carb attached. Since i'm assuming it'll need a carb rebuild/replace anyway, what replacements should I look into? I'm looking to make some 'bang for the buck' performance mods, and get whatever I can out of the car.

I also have plans for a header and exhaust upgrade. What are the best sounding/performance enhancing set ups out there? Any brands or products to avoid like the plague?

You guys obviously know much, much more than I do so far, so please point me in the right direction to have some fun with this thing!

Thanks!

 

[Matthew E. Herd]

Yeah, I forgot to mention that. At the place we have the emissions done, they realized it didn't have an air pump and of course, we had to install that and EGR, so its unlikely that you'll pass without those. You'd probably have to modify an older manifold to accept the EGR.

 

[Baxter]

Skip EGR. Point at the gulp valve and swear it's EGR. Or tell 'em MGs never had EGR.

 

[Guest]

find an exempt model junker, swap the number plates, retitle the car, they'll never know the difference

 

[Black MX-5]

Wow! Thanks for all of the advice!

Actually, my dad will be registering the car, and it will be under the antique New Jersey registration. I don't anticipate ever having to go through emissions for a QQ-plated car, as they're exempt.

So I can pretty much do whatever I want with the car, I just gotta figure out what that is.

 

[Bruce74B]

Wecome to the Forum from another Pennsyvanian!
If you are not going to drive it much (once a week) you should register it as an antique and skip the inpections completely. Otherwise it will be exempt from emission inpections, but must have the cat on it for State Safety Inspections. Antique lisenced cars do not get inspected for at all in PA.

If you live in PA, you have 30 days to register in PA (your profile says Philly) and violation will cost you $108.70 if you get caught.
Do it right and live easy...good luck!

Talk to Kim deB about joining a club or upcoming shows...I am sure she will be along soon, and is a great help in finding out about such things

Bruce