Not sure If I should have posted this in the Older, classic& antique section so if it should be feel free to move it. I just figured this section was more specific to my question.

I failed smog today because my mixture was WAY TOO rich. He told me that even at high RPM's it was rich. best I can tell I have the OEM Motorcraft/Holley 4180. I don't have the figures in from of me now but the acceptable reading was something like 1.8 and I was way up in 4.??

The truck has about 87,000 orig miles on it. The smog guy told me it may be mixture adjustment related or float related. I have had some experience with carbs and adjustments but not much. Before I attempt to do either thing I was hoping that some one could suggest a starting point, the float adjustment or mixture adjustment.

He said there is a vacuum issue as well. As to the location of WHICH line I know it was in the very back of the engine on top against the firewall. He said the line is not plugged but something controlling vacuum to that line is not functioning properly. He went on to say something else which I don't remember but my response to him was "well that's easy I will just replace the EGR valve" he then responded no its not the EGR its functioning its....I just don't remember what else he said.

I was so busy being pissed it failed and trying to figure out how in the heck it could be that rich that I was not paying attention. At any rate Im sure I can handle fixing this stuff but it all works hand in hand and I just dont know which to start with.

I also might as well add that I have looked and looked for the mixture screws on the carb but cannot find them. I did about 20 searches online and found nothing that shows them on this carb.

I know we are dealing with many possible causes here and rather thank me going in and screwing something else up that is related but was not the cause before.. and now after fixing the real cause is now the cause. You know what Im saying?? Im hoping you guys could help.

I should add that about 6 months ago and again this week the truck backfired from the exhaust. I mention this because i read a few posts about the PV and just wanted to mention it.

 

The vacuum source for EGR operation is a nipple located on top of the carb on the left side adjacent to the choke butterfly. A vacuum hose is then connected to a temp sensor and then to the EGR valve. I would temporarily by-pass the temp sensor and then check EGR operation....snap the throttle and watch for movement on the EGR stem, it will only move a small amount.

In regards to running too rich, check the float levels, real easy to check and adjust....idle the engine with the sight level plugs removed, the fuel level should be at the lower thread level, adjust needles as needed.

You could also have a blown power valve. This will require removing the primary bowl and metering plate.

If the mixture adjustment screw plugs have been removed and tampered with by a P/O, I would start by adjusting the primary screws out about 2 to 2 1/2 out and the secondary screws out 1 turn. You will need an allen wrench for this, sorry don't remember the size.

 

Thanks Beetle..I woke up this morning thinking sh@# I didn't put year or model of truck.. which is 1985 460 F350 1ton automatic. I need to add that somewhere on my posts.

Anyway sounds like you got the picture regardless. I will give your suggestions a try. As far as the mixture screws I dont know where to even look for them. I read so much stuff now I dont even know if Im looking for 2 or 4 screws. I was hoping to find a pic showing these but no luck.

I did find 2 diagrams here.. http://vb.foureyedpride.com/picture....ictureid=19636

AND HERE...http://vb.foureyedpride.com/picture....ictureid=19635

I just found them as Im typing this at first glance the second one looks like mine. I will look and see if it shows screws.

Thanks again for your reply..

forgot to ask how do i visually tell if the PV is blown?

 

I have the same year and model and I'm assuming yours has the stock Motorcraft 4180. The mixture screws are located under both float bowls, kind of hard to see unless you have a mirror or the carb removed. This link should help:
http://www.mustang50magazine.com/tec.../photo_08.html

 

I would suspect the power valve being blown.
The 4180 on the 85 GT also has mixture screws in the rear as well as the hidden front ones.

To check the PV, put the diaphragm side up to your lips and suck on it. The little metal head on the other side should pull in. This is how I have always checked them.

 

Ok so after reading a bit more about how vacuum system effects fuel mixture and how the PV may be causing a rich mixture ive decided to start with these items. But I have a couple of questions.


In this diagram Im having trouble discerning if the red line (pointed to) just goes UNDER the VCV valve circled and looks like this on the diagram because of printing issues or goes directly into valve and then the other lines intersect with it?

fdsafdsf

This is a pic of the two valves. (yellow and whitish with a bit of blue on it). Both mounted on the thermostat housing..I have been unable to find what either of these are called, can some one please tell me what each is called?

I have removed the line that goes from the dist to the yellow valve just for the picture.

Too me it appears that the red vac line in question originates at the main vac plugs into one of the ports on the 2 port valve (whitish) and then continues on to the 3 port valve (yellow)

Im fairly certain that the smog guy removed the GREEN line a the EGR valve to test it. This is the line that is not performing as it should. since it runs straight into the white port Im assuming this is not functioning BUT since im not sure of the lines I asked about above it may just not be functioning because I do not have it placed correctly.

 

Is yours a California 460? Mine is similar except your vacuum routing appears different. The yellow temp sensor restricts manifold vacuum to the distributor until engine temp reaches 150 degrees, then full manifold vacuum is applied. The other sensor is also temp activated. It prevents the EGR valve to operate until engine temp 150 degrees, this is to improve cold driveability. From your pic, it appears the EGR hoses are correct, the dist. hoses seem out of sorts.

 

Thanks again..Yes Im in CA. Well today I switched my hoses based on the assumption that the red vac line in diagram runs UNDER the circled sensor and does NOT go in to it. So now the lines coming out of the (whitish sensor/valve) go to the EGR valve and to the carb as shown in the diagram by the green and black lines.

Honestly I didn't notice much difference in the idle or at driving speed. Tomorrow I tackle the PV and see what is up with that. I also need to replace the Harmonic Balancer on this thing because it has definitely slipped.

 

I suggest getting a Holly 6.5 from any of the chains and checking the mixture screw openings and float levels I described.....good luck.

 

Can anyone tell me what model power valve I need? Im fairly certain its a 2 stage but cannot verify this. None of the local parts places have it. I found about 50 at JEGS.com but customer service could not tell me which one is for my vehicle.

If someone could suggest what I need I would appreciate it. Also I have read and been told that there is a protection device that can be added to prevent future blow outs but again finding it is proving very difficult.

I have done several searches on here but apparently Im not skilled in doing so. I mean this carb is notorious for this thing going out and I thought Id find the info easy on here but Im obviously not searching properly.

I would love to see all these common problems in stickies im sure it would cut down on a lot of repeat posts. Im willing to do what I can to help if the powers that be think its a good idea..

 

I would not recommend a 2 stage PV, just get the HOLLY 6.5. Blow out protection is just an option, I've had many intake backfires and never blew one out, as long as your engine is in tune it should never backfire. Pep Boys, ect. has that PV.

 

Thanks for the tip. I sent for a new valve and when I took off the old one I did as you described and it goes in just fine. So I guess I can assume it is ok.

Im going to put it back together and adjust the float. Some how it seem unlikely to me that the float level being out of adjustment would cause my CO reading to be 4 times higher than it should be. But then again Im clearly no expert.

Well put back together and the fuel transfer tube is leaking apparently the O ring must have came out or got crimped..Here we go.. I just want to pass smog

 

Recarbco - Carburetor Smog Diagnostic Chart

This site might point you in the right direction.