Hey everybody, :wow: is going on here ?!!!!!!!!! errrrr I keep having this problem with my carb thats driving me insane, I cannot get to adjust right, the only way I can get it to adjust semi right and to idle smooth is to have the mixture screw out about 4 turns, which I know is way to far out. Also the exhaust smells rich, it's not visibly rich but it smells like it, no matter where the adjusting screw is set at. I rebuilt the carb and it didn't help much, other than it smelling rich it runs great. Also, I know this sounds sorta stupid but does the larger jet go on the primary side or the secondary side, right now I have the larger one on the primary side, if I switch them it runs way worse, I know that seems pretty basic but carburetors are witchcraft to me. Should I just shell out the cash for a new one or does anyone have any idea on what I can do to fix this, thanks Chris Oh it might help if I told what car it is, it's a 73 wagon with a 2 liter.
the primary jet is normally the smaller one. there are a few instances where that is not true, but those are on race cars. it sounds to me like you have an internal leak some where, or a passage plugged up, or partially plugged. as i recall you have the 5200 holley/webber carb. that carb is usuall quite reliable, but there are a few tricks to keeping them tuned. it has been sometime since i had one though. you might be best off by getting a quality rebuilt carb from your local parts house.
something else struck me, check your float level and make sure it isnt too high, and make sure your fuel pressure isnt above 5psi as well. either of these can cause a rich condition especially at idle.
Several things:
First, I agree with rbohm about the primary side fuel jet USUALLY being larger, but I'm not certain about this particular carb-it's been too many years since I rebuilt the one on our '71. You are talking about the primary side fuel jet, not an air jet, correct?
Again, too many years have elapsed with too many other carbs in between, but many carburetors have internal brass AIR jets also, and these HAVE to be matched with the proper size FUEL jet, for the adjustment systems to operate properly. If your carb. has both air and fuel jets and they are sized so that they can be installed on either side of the carb, you may have the air jets reversed.
A fairly standard way to check for the fuel jet being on the correct side of the carb, would be to measure the diameter of the throttle plate openings of the carb.
If the larger diameter plate is on the secondary side of the carb. and is noticibly larger, it would tend to have a significantly larger I.D. fuel jet to supply more fuel to match the greater potential air flow through the larger opening. If both throttle plates are the SAME diameter, one jet might be slightly different, but wouldn't be liable to be nearly as different in size than if the trhottle plates were say 2 or 3 mm different in size.
Next, are you certain that this is the original carb for the correct engine and year of engine? If it's one that was intended for a 2300cc engine, the primary side fuel jet would most likely be too large for the 2000cc engine to idle smoothly. This MAY also be the case if the carb was one originally mated with an automatic transmission car and yours is stick shift. In general, a smaller displacement engine needs less VOLUME of the air fuel mixture to run at any given speed, (assuming that the relative valve configuration and numbers are the same and cam timing is the same)
If you still have the rebuilding instructions that came with the kit, try to remember if you had some parts that didn't match up with what was pictured, (or something missing, or something extra, too) if so, that's a good indicator that the carb may not be what was supposed to be on the car.
A leaking inlet valve can do what you're describing, as rbohm referenced. This is one of the most common problem areas in conventional carbs. Any continuous leak through the carb, by this means or any other, that adds fuel in ADDITION to the amount that is suposed to be being metered into the carb via the idle circuit (through the primary jet mainly) will be difficult or impossible to compensate for via adjustment of the idle mixture screw. After all, you can only add so much air through the idle mixture air passage, because it is a set size and once it's fully opened by backing the idle mixture screw all the way out, no more air can possibly flow through that hole.
Look very closely for any distortion of the resiliant tip of the needle valve. A wear groove or step on the tapered tip can make for a poor seal, possibly leaking slightly all the time, or sometimes sealing properly, other times not. A burr or a raised step on the brass part of the needle tip can also make the needle cock in the bore of the inlet valve, making it hang up or seal inconsistantly.
You really need magnification to check for this, as a tiny spot is all it takes to cause a problem. A piece of crud (sometimes rust) stuck in between the needle tip and the inlet valve seat, can cause a continuous leak too.
:stop:
the insanity.
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Thanks for the help everyone, I just got completely frustrated with it and happened upon a killer deal on a nos one, so I should have it a week or so, thanks again, Chris