To venture a guess by going backwards in your story - if a plug wire had
fallen off the cap, the car would have a misfire and serious lack of power.
These symptoms appeared or were present after you worked on the float bowls
and got the car started. You did say you took the cap off so that problem
was acquired at that point, I would think.
However, that would not have caused the car to not start. And if there was
a problem with the floats, there should have been other symptoms - like the
clicking of the fuel pump or gas overflow. For example, if the float or
grose jet on one bowl somehow stuck and would not let any fuel in, you
could possible have the backfire. But once you tapped on it, you would have
had the sound of the fuel pump filling the bowl up. Then you would have
your answer. You could have had flooding which would have kept your car
from starting, but I don't know about the backfire. The car would then
start after it cooled down. But you should have had fuel leaking from the
overflow pipe, some gas smell present. I have had problems with grose jets
not sealing in the past. Tapping on the bowl would fix it. A spark plug
inspection would have determined if you had flooding.
So your problems are probably remedied. However, if its been a while since
your carbs were overhauled, a cleaning and simple overhaul (replacing
gaskets and grose jets) might be prudent. Its inexpensive and parts are cheap.
David
67 BGT
71 BGT
At 05:21 PM 8/11/00 -0700, Max Heim wrote:
>Well, wise ones, I had a little bit of a scare today in my B, and I
>thought I'd see if anyone had any further suggestions beyond what I
>attempted.
>
>FYI: 66 B roadster, stock carbs (with Grose-Jets) and exhaust, Allison
>opto-electronic ignition, 5-main engine of unknown internal configuration
>(used Gold Seal unit acquired from wrecker)
>
>I drove up to Berkeley in the late morning -- 50 miles, all freeway,
>60-70mph, ambient temp around 75, I'd guess. Once in town there was
>fairly heavy traffic, so I had to wait at each stop light, but the temp
>gauge was stable at just over 190, oil pressure just under 40 at idle.
>Then I got stuck behind a double-parker for a couple minutes, and when I
>finally got a gap, and tried to shoot out, there was a very loud "bang"
>(like a backfire or exhaust explosion) and I lost power. After two
>smaller bangs and at least one puff of black smoke, the engine quit. I
>coasted around a corner and up a driveway onto the sidewalk, since the
>block was entirely red kerb, and the sidewalk in front of the Firestone
>dealer was very wide, and full of parked motorcycles, anyway.
>
>Turning the key, the engine cranked but showed no sign of starting
>(usually it catches on the first or second crank). Never having
>experienced such a dramatic explosive effect, I wasn't sure what to look
>at first. The distributor hadn't rotated noticeably and still seemed
>tight. I took the cap off and the little optical sensor jobber was
>intact. The plug wires were still attached. Oil and water were fine. No
>drips underneath (ah! that must be the problem! <g>). The fuel filter was
>half-full, as usual. I thought to take a look at the spark plugs for
>clues but my tool kit did not contain a spark plug socket (I seem to
>recall pirating it at some point, and I guess I forgot to replace it. Bad
>boy!).
>
> >From the phone booth on the corner I placed a call to Mike O'Connor at
>O'Connor Classics, my MG specialist. His mechanic, JR, suggested looking
>for a fuel float problem, possibly flooding. I wasn't too sure about this
>since the fuel pump hadn't been ticking while I was cranking it, and
>there was no overflow on the ground, but I followed his suggestion to tap
>on the float bowls to possibly unstick the floats, using the handle of
>the knockoff hammer. Then, since my destination was only one block
>further on, I left the car basking in the sun and went away to take care
>of business for 15 or 20 minutes.
>
>On my return I tried cranking it again, and it almost caught. Then, on
>the second try, it fired! By this time the temp gauge had gone down to
>around 130. I decided to see how it ran, and look for a better spot to
>tinker with it. I drove about 5 blocks, with it sputtering and missing,
>and found a Kragen's parking lot, where I snagged the last slot (popular
>lunch place?). There I removed the float bowl covers and blew out the
>jets. Nothing seemed to be particularly wrong wih them. I gave them a
>good shake, anyway. With everything back together, I started it, and it
>idled OK, though a bit rough, and under the hood I could hear a faint
>"tick" that sounded rather like an electrical spark. Reaching around the
>distributor cap to feel for loose wires, I felt a small shock. I shut it
>off, and found that one of the plug wires had totally fallen off the cap.
>I had checked these at the previous stopping place, but I had never been
>overly satisfied with the fit of this particular set. At any rate,
>starting up, it seemed to run perfectly, or as well it ever does, at
>least. I drove home the long (but less jam-ridden) way, 80/Bay Bridge/
>280/El Monte, at 70+ mph and 85 degree air temp, without further mishap.
>
>Sorry to bore you with all this, but what puzzles me is, what went wrong?
>and how did I fix it? As you can see, the evidence is somewhat
>"contaminated"...
>
>--
>
>Max Heim
>'66 MGB GHN3L76149
>If you're near Mountain View, CA,
>it's the red one with the silver bootlid.
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