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MGB 77 Stromberg issues

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Celtic 77

Celtic 77

Jedi Trainee
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I realize that the Z-S carb is less than ideal, however I was wondering if I can get some input before I input a ball peen hammer to the carb. I think the "O" ring for the dashpot is dead or dying. I check and refill the carb practically every 2-3 days. Could this be causing the stumbling and erratic idle? Cruising with a partial throttle it runs fairly well then all of a sudden it bucks and stumbles. Thoughts? My plan is two SU's and a new cat free exhaust.
 
grab the hammer and go for it. I rebuilt my ZS and went for an SU after all - never looked back. I am told that ZS carbs work if everything is original - smog equip/ air filters/ everything - all that was gone when I got my Midget.
 
I'd go back to the dual SU setup also. I never had good luck with anything else (even the 2 barrel downdraft Webers that everyone else seems to have good results with). At one time I had a 1977 and I put set of 1971 SU's and the 1971 cast iron exhaust that is more of a true header than just the straight manifold used later; really woke up the engine well.
 
Yep, two SU's and old-style exhaust manifold. The cast iron manifold is fine, absorbs a lot of the noise and is quite efficient compared with the later smog-control one. Only "next step" would be a 40 DCOE Weber and tube header, but only after some serious engine mods as well.
 
I just replaced the fuel filter... the rust that came out was stupid. I think this was a contributing factor in the stumbling and light throttle issues. Time to take it out for a carbon cleaning! After the red skies clear up here! So smokey here in New Jersey.
 
Sure seems like you guys don't like the Strombergs. Not sure I like them either but it seems a bit drastic to throw a pair of SU's at the problem. Those O rings are pretty easy to change and I'd try that first. I don't think the leaking oil would cause it to stumble but dry dampers might.
Tom
 
TomMull said:
Sure seems like you guys don't like the Strombergs. Not sure I like them either but it seems a bit drastic to throw a pair of SU's at the problem. Those O rings are pretty easy to change and I'd try that first. I don't think the leaking oil would cause it to stumble but dry dampers might.
Tom
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Well part of the problem may lie in a fuel filter that puked brown rusty water! Seems the simplest remedies seem to work first. Took it for a short ride and it seemed to perform a bit better...
 
I'd also start looking into why you had rusty brown water in your filter - likely means you have a tank with rusty brown water in the bottom and possibly a tank with pinhole leaks in the future. Had a couple B's with pinholed rusty tanks - much easier to just replace the thing than try to seal it back up.

In my case of switching back to the SU's, I already had them laying around and really wanted to go to the header style exhaust for airflow purposes - it was a quick and no-cost change for me.
 
YakkoWarner said:
I'd also start looking into why you had rusty brown water in your filter - likely means you have a tank with rusty brown water in the bottom and possibly a tank with pinhole leaks in the future. Had a couple B's with pinholed rusty tanks - much easier to just replace the thing than try to seal it back up.

In my case of switching back to the SU's, I already had them laying around and really wanted to go to the header style exhaust for airflow purposes - it was a quick and no-cost change for me.
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That I believe is the next step...drain, flush and make a planter from it!
 
TomMull said:
Sure seems like you guys don't like the Strombergs. Not sure I like them either but it seems a bit drastic to throw a pair of SU's at the problem. Those O rings are pretty easy to change and I'd try that first. I don't think the leaking oil would cause it to stumble but dry dampers might.
Tom
Click to expand...
Probably important to separate Strombergs (of which I have two waiting to go on the Vauxhall) and the Zenith Strombergs of Rubber Bumper MG fame. With the exception of California where OEM Smog stuff is mandetory, the ZS's and the smog stuff choked the cars. Some people seem to run them OK but mostly SU's wake the engines up. That said, for sure nothing really is lost by an O-ring, even as a stop gap.
 
JPSmit said:
Probably important to separate Strombergs (of which I have two waiting to go on the Vauxhall) and the Zenith Strombergs of Rubber Bumper MG fame. With the exception of California where OEM Smog stuff is mandetory, the ZS's and the smog stuff choked the cars. Some people seem to run them OK but mostly SU's wake the engines up. That said, for sure nothing really is lost by an O-ring, even as a stop gap.
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Can't wait to make mine a paperweight! I guess the only really annoying thing about the "O" ring is the continual filling of the dash pot. Plans afoot to replace the Z-S with either the 2 SU's or the Weber and the ancillary suff... manifolds, and a new exhaust. If that doesn't work rubber bands and a large red plastic propellor !
 
Finally PROGRESS...! Weber carb, header, manifold, exhaust system, engine mounts and front-end bushings!!! Found a reasonable guy in near Newton, NJ. Midnight Auto. He's a former SCCA racer, mechanic and now vintage racer. He has a stock of gently used parts that fit the bill. Almost ready!
 
Sounds like you've struck gold! Folks like that are tough to find.
 
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