4ac Carburetor Adjustment

[2jmk2]

I have an 85' SR5 that wont pass Ca smog because its x3 (should be .75 im at 3.0) over the limit on O2, the car is running pig rich. I have replaced al lthe vac lines and cleaned the EGR as well. I just want to know what adjustment does what on the carb, im tech and have access to smog equipt but im dumb when it comes to carbureted cars. Thanks!

Mike

[Carl H]

Originally Posted by 2jmk2

I have an 85' SR5 that wont pass Ca smog because its x3 (should be .75 im at 3.0) over the limit on O2, the car is running pig rich. I have replaced al lthe vac lines and cleaned the EGR as well. I just want to know what adjustment does what on the carb, im tech and have access to smog equipt but im dumb when it comes to carbureted cars. Thanks!

Mike

Hi , I just had richness issues with my 69 Corona I have just purchased. The car started to start hard hot or not start at all when hot. The float needle and float level went off, causing the manifold to flood with gas. it also showed symtoms as , only being able to turn the idle mixture screw out approx 1 turn and some gas weepage around the base of the carb.

I re adjusted the float level to get the bowl level slightly below the level line in the sight glass. Very close to center.... It then got very lean and had some slight surging at low speeds. I had to modify the idle, main and secondary making them bigger by 1 thousandths of an inch. ( approx 10%). I now can turn the idle mix screw to 2 1/2 turn , I still have very clean running spark plugs and very smooth linear throttle response. I attribute the new alcohol fuels and the lower octane needing the jet modification .

I would also check timing and choke function. But the high fuel level might solve your trouble , Also be sure the idle mixture screw taper has no burrs or marrs. I had to have mine re finished by my machinist and re do the 10 degree taper to remove a scar in the tapered point. The car is running like a rocket now... It has probably never ran better.... CH

[2jmk2]

Thanks, can you tell me where the adjustment screws are on the carb?

[Carl H]

Originally Posted by 2jmk2

Thanks, can you tell me where the adjustment screws are on the carb?

The mixture screw is usally down on the bottom of the carb and has a spring on it to retain the setting. Do not bottom it out hard as you can damage it. Usually carbs are set at approx 2-3 turns backed out. The idle speed screw is the one that touches the carb likage 9 mine is tucked down way low and took me some time to locate, You should buy a carb gasket kit and they have set up and an exploded veiw of your carb to see where it all goes. First you need to check the float level , setting the floats can use shim gaskets to change needle seat hight, Or some like mine use a simple bending of a float tangs that contacts the needle to alter float settings. Also don't idle the motor for long periods when tuning and change spark plugs when tuning, avoid stale old gas as it goes bad quickly.. Don't over tighten screws and warp all the surfaces !......CH

[Punkrampant]

Hope this helps. Its fwd so its just an example.

http://www.ae86cafe.net/library/Manu...A%20engine.pdf

[Punkrampant]

Im having a similar problem on mine, I checked the float height and it was perfect. Does the egr valve hold vacuum?