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Heat Shield [Is it necessary]

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Naomi

Jedi Hopeful
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I was just looking at the Moss Catalog and it shows a heat shield behind the ZS carb the hubby took off my 80 MGB when he installed the Weber Set-Up. Does that need to go back on? I was actually looking just for that purpose because I remember Tony jumping all over me a couple of years ago (in another forum) when he found out I didn't have one behind the ZS. Seems as if Tony said something about a fire hazard. Anyway the hubby did put one on back then but now, with the Weber, there ain't nothing there but them pipes and the engine. It ain't needed is it /ubbthreads/images/graemlins/confused.gif


Naomi (Owner of a 1964 MGB, a 1979 MGB, and a 1980 MGB. Each repaired hundreds of times but still loved /ubbthreads/images/graemlins/smile.gif
 
The manifold can get really hot. <<<stoopeed woomun question ahead>>> Webers have manifolds, right?
 
every car engine has manifolds - and every carb too.
 
Naomi,

you do not need a heat shield with the Weber setup.

Paul
 
Paul is correct. The Weber is designed in such a way that it's not as dagerous as the ZS was. Besides, I don't think anyone actually makes a heatshield for a Weber conversion on an MGB, do they?
 
I knew that Pinky, I was just testing you. I figured it out after I asked that. Thumped myself upside the head and said 'duh.'
 
*bites tongue* /ubbthreads/images/graemlins/jester.gif
 
Rob when I was looking in Moss the one for the mid 70 MGBs looked like it might work?
 
It's okay Janel---we're just gurls /ubbthreads/images/graemlins/smile.gif This does bring up another question though---I remember Tony fussing that my MGB was going to burn up because gas would fall from the ZS . What happens if if falls from the gas line or Weber /ubbthreads/images/graemlins/confused.gif
 
Actually I cringed a bit when I hit the post button... A few really odd engines don't have manifolds for the carbureter.

You thumped yourself - ouch - now rob is resting - hehehe
 
Naomi, I don't think any of the stock MGB shields will fit without modifications. I believe they were all designed to fit between the carb and manifold. The manifold for the Weber is so different from the stock MGB manifolds that it would not be a simple bolt-on operation.

The problem with the ZS units, was the Catalytic Converter was located directly under the carb. Plus the ZS has a plastic plug in the bottom of it that uses a single rubber o-ring to seal it. If that o-ring were to fail then you would have gasoline pouring onto a hot catalytic converter, if the heatsheild is missing.

When you converted to the Weber, you not only changed the intake manifold you ALSO changed the eshaust manifold to either a header, or one of the early stock cast iron exhaust manifolds. With these units, the exhaust manifolds do not get as hot as a catalytic converter does. So, while there may be some risk of fire *if* a fuel line bursts, it's not as bad as the case with a stock ZS system. Plus the float bowls on Webers don't have the problems that I described about the ZS.

In short, completely stock ZS equipped car (along with stock catalytic converter) gets REALLY hot directly under the ZS carb. Weber conversions typically get rid of the catalytic converter, so the heat under the carb is greatly reduced.

The fuel pressure going into carburetors isn't that great so fuel line failure isn't a common occurance. You'll be able to determine if the fuel lines should be changed during normal maintenance long before they break.

Make sense?
 
Sure does Kenny and I really appreciate your taking the time to explain. That is very kind of you and this is one great forum /ubbthreads/images/graemlins/smile.gif

PS: The hubby did do away with the catylic converter when he did the Weber Set-Up. Matter of fact all the works came from Tony /ubbthreads/images/graemlins/smile.gif
 
One thing to watch on the weber(assuming it's a downdraft?) is the throttle plunger diagram...it gets old, cracks and leaks right on the header......Since the heat burns the fuel off right away I didn't notice it until I was running it with the hood open for some reason and saw the stream of gas landing directly on the headers....No way to knowing how long it was doing that before I noticed!

BTW: Did you notice any change in performance between the ZS and the Weber?? My LE has the weber and the 78 have the stock ZS's...I don't really get much of a change, but I am yet to drive them consecutively.
I guess part of it depends on the condition of the carb to start with.
 
Hmmmm, Maybe Doc will send me the HS6 he was thinking of sending the other night... I'd be able to tell you up front if there's a difference with different carbs.

But I get about 13-15 mpg with my ZS in it's incomplete/unrebuilt state. I would love to see anything close to the 24+ mpg I've seen listed elsewhere.

Last tank of gas - I ran out at 120 miles. Thats worse than any car I own. But, I'd be able to tell you the "seat of the pants" performance difference too.

Doc?
 
Na - heat shield for ZS or SU's - none needed for weber...if you don't have it on the original carbs, the gas gets hotter than necessary - & can even boil....
 
It is a Downdraft and here goes:

ZS vs. Weber Comparison

By owning several MGBs, with two of them being post 75 models with excellent working ZS Carbs, I’ve recently had a most unique opportunity to compare a Weber to a ZS. The hubby removed the ZS from my 80 MGB and replaced it with a Weber Down Draft. That left me the 79MGB with original ZS to compare the two. I've been driving them daily (alternating) for several weeks and here are my “very unscientific” findings:

1. The ZS is more fun because I like filling up the dashpot with a mixture of oil/transmission fluid and the questions from people when the see me doing so.
2. The Weber is self sufficient once adjusted which does take some initial effort.
3. The ZS serves my every need.
4. The Weber gives the car a great deal more power which is very noticeable.
5. The ZS does hold back on power and that has now been proven to me.
6. The Weber provides better fuel economy.
7. The ZS gets a couple of miles less per gallon than the Weber.
8. The Weber installation seemed to clear up/open up the engine bay.
9. The ZS, with its air cleaner, takes up a great deal of room.
10. The Weber 0-60 MPH is almost immediate.
11. The ZS 0-60 MPH is a little slower but it will get there and beyond.
12. The Weber actually feels like it has a passing gear when I am cruising
about 3000-4000 RPM and step hard on the gas pedal.
13. The ZS has kept me going for years in mountains, towns, and
Interstate and I do have a heavy foot.
14. The Weber makes me want to push the hubby more to fix the overdrive because it now seems as if I need another gear.
15. The ZS doesn’t care if I have overdrive or not and just keeps on going.
16. The Weber warm up idle is at a lower RPM than the ZS.
17. The ZS warm up idle is about 500 RPM higher Weber.
18. The Weber installation made the car sound a little different in a nice way.
19. The ZS sounds fine as is.
20 The Weber cost a bunch of dollars.
21. The ZS is free--it came with the car.
22. The Weber is fun to drive.

FINAL RESULTS: I have to admit the Weber is superior to the ZS (I can’t believe I’m saying that) and I would recommend the installation if you have the change laying around to buy one and the time to install it. By the way installation is way less than a day. On the other hand if I had a completley original 75-80 MGB I “would not” remove the ZS. Now you have my professional opinion --don't you wish you had not asked /ubbthreads/images/graemlins/smile.gif

Your turn,
 
You dont need a heat shield,but the carb still sits over the h ot manifold, any leaks and you still have the same problem.The heat shield from an older model b will work just fine and can be had for $79.00 or less from moss
 
[ QUOTE ]
I have to admit the Weber is superior to the ZS

[/ QUOTE ]

While there *are* some ZS enthusiasts out there, I think the vast majority of MGB owners will agree that just about any other carb you can get for an MGB is "better" /ubbthreads/images/graemlins/laugh.gif
 
My old 79 had a Weber on it without any kind of a heat shield and never had a problem running or heat soak.(Static heat). In fact, if it wasn't for making it look like it's supposed too,(twin SUs), I'd put a Weber on the 72! Bolt it on and forget it! /ubbthreads/images/graemlins/thumbsup.gif /ubbthreads/images/graemlins/thumbsup.gif PJ
 
<rant>
While this topic has been and likely will be shuttled back 'n forth for as long as there's gasoline to burn, my take is: run the induction device most consistent with the 'goal' you have in mind for the car: Performance, mileage, originality, etc.

I prefer Webers. DCOE ones. On an MGB the dual SU HS4's are second choice. Single HS6 or down-draught Weber next... and that poxy Zed S thingie is at the bottom of my personal list. It's a curling stone or a good wheel chock, mebbe a door stop if'n it's cleaned up well, IMO. They're fraught with potential dangers/failures. Rob pointed out the O-ring/plastic "drain" cap one and I consider that the most dangerous. To put a METAL cover on it (read: heat sink!) then have it sittin' OVER a cat-converter really "caps it" for me. Admittedly WHEN maintained well, they're adequate. Now most of the Zed S equipped cars are in the hands of enthusiasts... that weren't the case when they were two-to-ten years old. PLENTY of 'em were driven 'till collapse. I've seen 'em. Tony's yard is full of 'em, too:

"Spend HOW MUCH on a new converter, carb rebuild, plugs, valve adjust!?!? --- nahhh... I'll wait." etc.

I could go on about this for a looong time. Point is: run what's appropriate for YOU. We here in this group are not "average" owners of these cars. That crowd gave 'em up TO us. We're making sure the examples we have will live past US and be a source of ~fun~ for the next owner(s).
</rant>

Oh, and Kenny: This HS6 is the mate of the one Rob has... so that would make your B and his "related". Kinda like kidney transplant recipients. How *sweet*.... everybody say: "Awww..." /ubbthreads/images/graemlins/wink.gif
 
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