tuning the mazda carb

Does anyone know how to fine tune a stock mazda b2200 carb? I wanna do mine and was told that its harder then just screwing some screws, it could make it waste alot of gas or provide insufficient amount. if anyone knows please post, and pictures do say 1000 words
Thanks in advace

This is an awesome thread - Great idea. There are always questions and comments about them.

its not by screw location.. if that was the case then they wouldn't be adjustable.. i know how.. but its by experience and listening to the motor.. not something you can explain on a thread. I would sudgest going to a local carb shop.. someone who rebuilds them and kickin them 20 bux to do it.
Mike

Actually.. My uncle taught me a sweet little trick that had my carb tuned perfectly in about 5 minutes.. my truck sailed through emissions with a scored HC rating of 22. Granted this was right after I had replaced the rings and the valve seals.. but my previous score was 1547. Yeah.. she was smoking like a hippie van at a grateful dead concert.. anyway.. on to the trick.

You will need a vacuum gauge to do this. Hook the vacuum gauge upto a open vacuum nipple on your intake manifold. The closer to center of the intake the better.. but even if you use one of the nipples in the rear near the fuel pump like I did it should be fine. Start up the engine.. you will see the needle on the vacuum gauge bounce around quite a bit.. slowly adjust your mixture screw until the needle stops bouncing or until its bouncing so fast that it isnt moving very far up & down the gauge. Unless your valves are seating perfectly.. you will get some needle bounce.

Notice that I didnt say which way to turn your mixture screw.. this is because you may need to go either direction.. if you get black smoke out of your tail pipe.. likely you are running too rich and should turn the screw CLOCKWISE or IN to lean out your mixture. If you are running too lean.. Your engine will run too hot.. so you would want to turn the screw COUNTERCLOCKWISE or OUT to richen up your mixture.

Keep in mind that your timing and idle speed may also need to be adjusted. Timing should usually by around 6-9 degrees BTC, depending on your year and engine. If you lean out your mixture and your idle goes down.. increase your idle either via advancing your timing or via the idle speed screw. I like to run my timing a bit further advanced than what the stock application calls for.. I find that it gives me a bit more power. Currently I am running about 11 degrees BTC. (I used my dial back timing light to set it) Though I also only run Midgrade gas in my truck or Super. If you advance your timing to much you will get knocking and pinging which often indicates that Detonation is occuring. Detonation is bad mojo and will destroy your pistons and rings very rapidly.. so advancing your timing to far is definately something to be avoided.

When adjusting your idle speed screw.. you need to make small adjustments and wait after each adjustment for the computer to make the change. Unlike the mixture screw.. you idle screw (at least mine anyway) seems to be a lot more sensitive to adjustment. So go in small increments and wait at least 30 - 45 seconds after each increment before the next.

Anyway.. this stuff seems to have worked fine for me. Hope it helps you guys out.

Cheers

Tunes67

Wow tunes, that sounds like something i will try soon. I think my carb isnt putting out enough fuel at higher RPMs, going up a slight hill at 3k RPMs and flooring doesnt seem to have an effect on the highway. Any more tips and tricks anyone?

Awesome, by far this is the most useful mechanical responce I've heard.