I got it right! Or did I...

C

Commander Toasty

Member
Rebuilt my Zenith and hey - signs are good I didn't leave my watch in there.

Started right up and strong with a good smooth idle, smoother than I ever remember. Took the idle down to about 2RPM and it still hangs in there ... well OK maybe not two but very low. And it revs up fast and strong. The GAV has far more influence than before and the best position for it now is about half a turn different than it used to be. Keeps running when I come to a stop which is what drove me to rebuild in the first place - wouldn't do that these past few months. All signs are good...

Except one.

And it is the same as before I performed surgery on it. The mixture screw is happiest fully seated, all the way clockwise. It runs fine backed out, but it peaks fully seated.

Now that could mean a leaking intake manifold, and I don't right now have a can of carb cleaner to test that, but I don't hear any hint of a intake leak hiss and I'm skeptical that is the problem.

What, in a tired carb and a fresh one, might be the cause?
 
I did. But while I was working on that portion, installed a new shaft and throttle plate, I noticed the throttle plate did not completely seal. It is the thick one with beveled edges that are designed to seal but it seemed a bit small. I could hold up the body and see light through the edges. Might be enough to do the trick.

That's the throttle portion I'm talking about. The choke seals completely.
 
Last edited:
Tom Endy has a great writeup on Restoration Tips for going through the carb, and he mentions that if you can't find the sweet spot it may be due to incorrect timing.

Now - I don't see how that is a cause, unless the timing is way off. And for that matter I did find the sweet spot... all the way in! And I think my timing is correct as well.

It's a mystery.
 
Its not hard to adjust the throttle plate in the shaft,but, the stop screw has to be backed off a bit.. Also the idle mixture needle and seat may have been damaged a bit at one time and are 'ringed ' or the needle may be slightly ' warped '.. There is still chance that a passage may not be clear but it seems like you have cleaned everything pretty good.. It doesn't much 'crud ' to foul things up..
 
Yo CT, when the throttle plate is closed you should not see light around that bad boy when looking through it whilst aimed at a light source. If you do, back off the shaft lock screws about 3/4 turn, close shaft and sneak the screws tight. Check it again, and repeat til it has little as possible light showing. Hopefully this is a Zenith, if a tilly check the base to manifold for a true fit and not over gronked flanges.

Good luck,
GW
 
You must log in or register to reply here.
Back
Top