On Thu, 25 May 1995, Dan Crone wrote:
> OK. I'm out in the open now. I've emerged from 3 months of lurking around
> the British Car Lists to pose my first question to the list. My 75 Spitfire
> now has a problem which I created. Over the winter, I rebuilt the Zenith
> CD150 carb. Piece of cake, or so I thought. It seems to perform well, and
> it no longer drips gas.
> Now for the new problem. Under full throttle, a buzz emerges from the
> engine. The noise sounds exactly like the fan blades are striking something
> tinny. I thought it was the tinfoil air intake tube striking the fan
> blades, but with the tube off the car, it makes the same noise.
>
> Next, I thought it was a vibration, and I taped down everything that looked
> like it might be striking something. (Duct tape & WD40 are ubiquitous
> products, aren't they.)
>
> I now think the sound is from the carb itself. (It could be something else
> went south during the winter, but the carb is the only thing I've "repaired"
> on the engine.) My guesses are that I freed up something that was plugged
> up with gunk,or assembled/adjusted something incorrectly, but what? Has
> anyone experienced this after rebuilding their carb? Or does someone
> recognize my description of the sound as being indicative of some other
> problem? (What would a bad or failing air pump sound like, for example?)
Dan,
I have two LBC's...a '75 Spitfire and a '78 Midget; they both have the
same 1500cc engine. The Midget I bought in Florida with no emissions
"stuff" left on it. The Spit I bought here in Colorado with emissions on it.
The FIRST difference I noticed when I drove was a whining similar to the one
that you describe, and it's coming from a brand new air pump. Since I'm
tuned to what this 1500 engine sounds like, the sound stood out INSTANTLY.
It's annoying I can tell ya!
Maybe the air pump is at fault.
Try removing the air pump temporarily.......
Nick D. Benson
Dept. of Industrial Sciences
Colorado State University
Fort Collins CO
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