Were I to buy a carburetor, I would probably NOT buy one from MAC. Not that they wouldn't back it up if there were problems, but theirs is certainly "off the shelf." They'll take yours back and replace it with the NEXT one off the shelf - meanwhile your problem, if you perceive one, will likely still be there.
Were I to buy an off the shelf carburetor, I would probably rather go with Snyders or Brattons. Or better yet Berts who have had rave reviews recently on the quality of their rebuilt units.
And I think rebuilt a better game than something new and off the shelf anyway. And rebuilt from any of these three sources would have FULL attention and rework possible to make it the best unit possible. Attention to detail in rebuilding and flow testing of the individual unit is what makes a successful carburetor, either new or rebuilt. My feeling is that rebuilt offers a slightly higher quality product at more cost effective price.
Now Zenith or Zenith w/ balance or Tillotson X you'll find the marketplace somewhat divided. I myself prefer the Tilly X. It gets slightly better gas mileage than the Zenith, doesn't seem to have stumble problems (some of the Wiz or other so called "high mileage" units can be problematical) and parts and documentation are available for DIY on the Tilly X.
But there are those who are messing around with Zenith or ZBalance and they're happy with their units too. Design of a carburetor is a compromise of a bunch of interfering factors and what works for one driver may be unacceptable for another.
The balance modification on the Zenith is so it will run an air-maze filter without issue, but I've run my Zenith unbalanced with an air-maze and didn't notice a bit of difference either way. So for me the jury is still out on that one.
The biggest single thing you can do with a new carburetor to assure performance is to check the float level using a flex tube. I would consider this mandatory. Beyond that it's simply a matter of twiddling the idle speed for a nice low idle, and the idle richness. Catch up with one of the various booklets by Moller or others which will help with initial setup. I think there may be some instructions online too IIRC.
And I wouldn't rule out doing your own carburetor. It's not rocket science. And not a large matter to solder and port the jets and flow test them yourself. For what costs upwards of a couple of hundred for the rebuilt units can be done in one's basement for about $40.
And the knowledge and confidence you will gain will be PRICELESS.
Joe K
