Need to find the fuel air mixture screws on a rochester carb durajet 210

How to Adjust Fuel and Air Mixture On A Carburetor By ...

? 5:54
https://www.youtube.com/watch?v=39Wcbp6_yNQ
Feb 23, 2014 - Uploaded by TheWhatisright Hopcorvetteman
It is a standard 350 Chevy with no real modification. .... missing something or can they be in a different location on my carb ( 81vette rochester quadrojet ). ... There are two fuel mixture adjustments on the rochester Carburetor.

Do you have a Holly on that ? if not then, you have to pull the carb. apart to adjust the fuel/air mix, are you talking about the idle air mix screws, this only adjust the idle mix, not the fuel ratio when running above idle, I have seen slots (screw driver) oval, hex screws, your going to have to see which one you have, take the air cleaner off and reach it from the front of the van.

Your going to need a professional that can
figure out how to restore your very old vehicle
to OEM Specs,so you can pass inspection

The air/fuel mixture screws are usually capped off and the adjustment might not be possible, but if the air/fuel mixture screws are exposed then turning them in will lean out the fuel mixture, and turning the air/fuel mixture screws out will en-rich the fuel mixture.

With the engine fully warmed up and at normal idle speed adjust the air/fuel mixture screws one at a time, and turn each air/fuel mixture screw in until the engine just begins to mis-fire, then back out the air/fuel mixture screw one and a half turns to two turns to achieve a smooth idle.

Be certain that the air and fuel filter(s) are not plugged up (there might be a fuel filter inside of the fuel pump as well as the fuel filter/stone at the fuel inlet to the carburetor) and keep in mind that the minimum octane requirement for that engine is 91 octane, and 92 octane is the average octane rating for the premium higher grade fuel, so a bottle of octane booster added to a full tank of fuel will greatly improve the way the engine idles and performs.

That engine should have an electronic HEI (High Energy Ignition) distributor with the large distributor cap and with the ignition coil inside of the top of the distributor cap, and keep the tune-up parts in good condition and replace them when they wear out. The tune parts would consist of the distributor cap, ignition rotor, spark plugs, spark plug wires, and the spark plugs should be gapped at .045 in.

For better performance from your El Dorado a 1 inch spacer under the carburetor will really help a lot if the hood clearance will allow it, and you will need to set the ignition timing to 10 degrees before top dead center, and adjust the accelerator pump on the carburetor for maximun pump efficiency so that as soon as the throttle is opened there is two healthy squirts of fuel from the accelerator pump, and they should squirt as soon as the throttle is opened, and if the throttle can be opened and the accelerator pump does not squirt fuel at the same time as the throttle is opened, then there will be a lag or stumble from the engine on take-off and a severe loss of engine performance. (The accelerator pump must pump fuel into the carburetor at the exact same time as the throttle is opened)

For better performance check the adjustment of the secondary throttle linkage, and let me know if you require assistance with any of the proceedures.

Be sure that the vacuum lines to the EGR valve are correctly routed and that the EGR valve is not operating at idle.

Also, that engine has a plastic timing gear that was used for the camshft timing gear, and I would seriously suggest that it is changed before trying to get any performance from that engine.

Other than those modifications, the engine would need a better camshaft and the catalytic converter removed to increase the performance of that engine.

Here are some images to help assist you.


Fuel Pump Filter:










Rochester Carburetor Secondary Adjustment:

many of the late model cars & trucks can't be
adjusted some of the carbs are preset some you can force and some don't have an adjusting screw for the jets if the carb is in good working order but needs a bit more fuel you u must adjust the float for more or less fuel check to make sure the float valve is clean free and not sticking ..

Check your ignition timing at 3500 rpm you should have about 40 degrees of advance If not, something is sticking in the distributor, either the vacuum or mechanical advance. This will cause a big reduction in fuel economy. Also, check your tire pressure. The cfm on a rochester is really not important. The primary bores are so small and they are the only thing allowing the mixture in most of the time.

In the late 70's they mandated that the adjustment screws be capped over. If they haven't been exposed, there will be two plugs covering them on the baseplate. Air adjustment screws are always somewhere on the base of all carbs with the only exception being on Holley 4bbl carbs used on performance engines (definitely not yours)

typically it's close the screw(s) then open them one and a half turn.

There should be one screw (I'm assuming it's the Carter YF carburetor 1 barrel) that's by itself away from linkages etc, more to center at base of carb where it meets manifold, that is angled approx 45 degrees going in to base. That should be your mixture screw. What symptoms are you experiencing anyway?

Yes, Colorado is much higher in altitude. Do to higher altitude the barometric pressure is less than sea level by a long shot. Lower barometric pressure mean that less air is entering your engine. Which in turns mean that your engine is now running richer than it was at a a lower altitude. So I recommend checking you engine timing, and adjusting your carbs air/fuel mixture. yes this means that you may need to rejet. but first there is a screw on your 22r's carb that you must adjust to lean the air mixture just right. I have had a stock 22r carbortor before and never had to rejet it. i probibly should have but it ran fine at sea level and all the way to about 10000 ft. after 10000 feet i had to lean the fuel mixture to even alow the engine to run. This screw that you must turn is hidden due to toyota not wanting you to tamper with it and burn your engine to the ground by running your engine to lean. it has a metal plug on the passenger side of the carb about the size of a pencil eraser. you must drill that out and then you can adjust the air fuel mixture. Clock wise is to lean the air fuel. and Counter clock wise is to richen the air fuel mixture.A good rule of thumb is to turn the air/fuel screw all the way clock wise and then back out about 2 and 1/2 turns. That is the factory adjustment. you may only need 2 turns out. Best of luck i hope you get it running perfect. Try this adjustment first then if it still runs rich then think about rejetting.

Here is a picture of what i am talking about.

#1 is the air/fuel mixture, #2 and #3 are cold and warm idle screws.
#4 is a A/c idle adjustment.