A buddy of mine got an aftermarket carburetor for his 350 and we’re both stumped on how to adjust the rich mixture screw. I’ll post a picture of it being blocked off but honestly is there any way for us to mess with it or just leave it the way it is?

 

Well, we can see the picture, but, typically, one removes the plate. It's not breaking the law.

 

 

That’s the screw i’m talking about i’ll post the picture when he sends what it looks like

 

That's above the power piston, I believe the adjustments are limited to spring strength and the primary needles' size. I think all this is done with the air horn off. You might not even need to remove that. It's been a while since I've been in one.

 

This is the tamper proof thing i’m not sure if i can take it off because it might damage the carburetor or anything near it

 

Ok, that is staked. You see it on the right side of the middle. The carb is already damaged by it being peened in over the plate. You need to drive that bit out so it is in its original spot. I would do it with a hammer and punch coming in from the left. Who cares if you gouge the plate, it's leaving.

 

I appreciate the quick Replies Koda, i’ll tell my buddy that tomorrow when i’m over . I also appreciate the extensive knowledge

 

There should be some better replies in the AM, I'm just up later than most here.

 

You didn't mention the year of the car. The chinesium aftermarket carb is a CCC (computer controlled command) carb, which WILL NOT WORK on a non-CCC car except at WOT only, if you make it that far. It will always want to run pig-rich. That circled part is the idle air bleed valve (IABV). Is that the original carb or just a pic off the interwebs? I ask that because that picture shows an IABV that has a letter stamped on top. That typically is the last adjustment you would do. When adjusting an IABV, you have to use an analog dwell meter and adjust it like 1/4 turn at a time, wait for a bit, then check to see what it does to your dwell. On some applications, you have to adjust it along with the base plate adjustment screws. It's NOT something you crank up and down ***** nilly. To bench set it, there's a special tool you need to use. You're working with a CCC carb, so you better be doing it right. The chassis service manual has all the setting info you need to adjust it, but you must follow those procedures exactly or it will run like crap. There's two tiny little rivets that have to be removed to take the plate off. If you do that, make sure to get all the little pieces out of there. You will also likely need to get a few special tools. Like for one, an analog dwell meter.

The rich stop adjusting screw, if equipped, would be in that little hole immediately in front of that plate, underneath a blind plug on a factory carb. I don't know a thing about these chinesium copies. It's actually on the inside of the fuel bowl which limits the amount the M/C solenoid paddle rises to the top. With a later Y-engines (I'm betting if it's an Olds 307 engine), you may not have a rich stop as that hole probably isn't even drilled as the rich stop is "built in" the lean stop screw assembly. If it has a letter stamped on the top of the IABV, it should have a rich stop adjustment separate. I think they went with the fixed rich stop starting in 1984, but I don't recall exactly.

The lean stop adjusting screw plug appears it may be that flat-blade screw looking thing just in front of where the rich stop plug is. The lean stop does the opposite. The lean stop adjustment adjusts how far down the primary rods dip into the jets on the leanest point of travel. Total travel of the rods should be a window of about 1/8". The lean stop adjustment on a Y 307 engine just raises or lowers the window as the total travel will be fixed already.

If you don't know what you're doing around a CCC carb, find someone who does. Because if you don't follow the service procedures to a T, you'll never get the car to run right.

 

X2, CCC carbs run very well when tuned properly; but, only if they are tuned properly. The chances of improving anything by changing unknown adjustments on a CCC carb are slim to none. It is just one of those situations in which the procedures should be followed exactly and if they aren't followed exactly then doing nothing is probably better.

 

A few things to note. First, get a factory Chassis Service Manual for your car. Among other things, the manuals for the 1980s cars tell you exactly how to remove those anti-tamper features and how to then correctly make adjustments. It is certainly possible to run a 350 on the CCC system, since the computer only controls the mixture on the primary side of the Qjet, but you CANNOT simply bolt a rebuilt carb onto the engine and expect it to run right. More to the point, unless you follow the CCC adjustment procedure in the manual EXACTLY, the car will never run right. And as noted, if you try to run the CCC carb without the computer, the primary metering rods are spring-loaded to the full open position, causing the car to run pig rich. It is impossible to lean that out without the computer controlling the carb. The CCC system requires the matching computer controlled distributor to operate also.