5200 carb vac. diagram & vac. advance ?'s

[rab]

Alright, I bought an '83 ranger 2.0 4 speed, the motor was junk, I pulled a 2.3 from my buddies '78 fairmont to swap into the ranger.

I have deleted the emissions stuff as well. I have a few questions regarding the ports/vacuum lines on the carburetor.

It has the stock '78 5200 2bbl carb, does anyone have a diagram of all the ports on it, i.e. what each port is for?

My two main questions are, where does the vacuum advance from the dizzy get routed to?
What is this port for (the bigger one in the bottom left of this pic)?

 

[Mark_88]

Howdy...that's the same carb I have now...

The vac advance from the distributor goes to either the main vacuum trunk (you should have a few extra ports on the manifold) or one on the side of the carb. I tried using the carb side port but did not like the results so I put mine on the back vac tree where the brake booster connects to the intake. Post a pic of the intake if you have problems finding these as yours may have a different intake or layout than others of that vintage.

The port in the bottom left is for drawing fumes from the charcoal canister on startup of the engine...

There was a recent discussion where I learned the actual direction of the fuel flow from the canister and that port is where it comes into the carb.

There is an actual diagram of the carb in the On-Line Repair Manual at the EBSCOHOST website...there is no direct link to the image...and the image is a bit small but can be exploded...here is the link...

Once you are at the site, you will be prompted to enter the vehicle year, make and model...use the info from the vehicle the engine came from...of course...

Collection of online repair manuals for all makes and models.

http://search.ebscohost.com/login.aspx?authtype=url,uid

User ID: tech
Password: tech

 

[rab]

right now i have the vac advance hooked up to a intake port on the vacuum tree thing,i was not sure if that was correct port or if there was a certain port on the carb it should go to? i would like to hook it up the way it would have been routed from the factory to the correct port (iirc in factory form its intertwined with a bunch of the emissions stuff, which i have deleted) i have not messed with alot of carbs, most of the stuff i mess with or have worked on is fuel injected, so with that being said if the port on the carb and intake are accidentally the same i guess it would not matter, but i dont know that. I thought i remember looking at or reading something about port or full time vacuum.

The truck started and it ideled fine this way, i have not drove the truck yet cause it needs a few other things hooked up before it is driveable.

can i just plug that port that goes the fuel vapor box, or does it need to be open? that is if i delete that also.

i will have to take a look at that website latter, thanks for the help so far.

 

[Mark_88]

You're welcome...I don't see too many people using that carb but I've found it not too bad...although I've considered moving to a different one...this was a far and wide huge improvement over the stock carb.

That port for the canister only works on engine startup. It opens (although I don't know how it does this without vacuum from the engine) and sucks and vapors out of the canister...

Until Adsmo8 advised me otherwise very recently, I thought it was supposed to be a return line to the tank...but it works the other way around. Deleting it might cause excess gas vapors to linger a bit longer than they should and may be a fire hazard...but I'm not even sure that mine works...I searched Charcoal Canister on cars and found a few pages through Google so you might find something useful that way...

There are a few tweaks on that carb that might come in handy if you need them...if you find it floods (gas actually runs over the top of the carb) or if you have problems with idle or fuel mixtures I might be able to help you with that...I think I've finally got mine to the point where it would run good...once I replace the head and possibly the block I might find out...

Mine ran perfectly for about a year without any problems...and the problems were minor once you know how to fix them.

 

[rab]

thanks, so is the vacuum advance line routed correctly?

also does anyone know what the oil filler cap looks like, does it have a breather hose on it or is it sealed, i went to napa site and seen they showed one with a hose on it?

 

[Mark_88]

The 2.0 oil cap had a vent hose that ran to the breather on the carb...this, generally, results in oil gunking up your air filter...but the vent is to let off crank case pressure in the valve cover...which is important to proper engine operation.

If you don't have a problem with oil in the breather, connect the hose to the opening on the breather (there should be three or four vents on the breather for that carb that are covered over with rubber plugs).

There is a small filter that you can put in behind the hose at the breather that helps stop some of the oil from getting into the breather and this works fine as long as you keep it clean...if you have to clean it more than once a month or so then you may be starting to see the results of excess blow-by.

 

[Mikel89us]

The vaccum advance should not be hooked to the vacuum tree... It should be a ported signal that pulls high vacuum at part throttle. With it on the intake vacuum signal you will have high advance at idle and it will drop off as you give it more throttle, not a good thing.

 

[rab]

so does the carbed 2.3 have a vented oil fill cap?
if so i just run a breather filter on it.

does anyone know which port on the 5200 2bbl is the ported signal?

 

[upnsmoke]

The vaccum advance should not be hooked to the vacuum tree... It should be a ported signal that pulls high vacuum at part throttle. With it on the intake vacuum signal you will have high advance at idle and it will drop off as you give it more throttle, not a good thing.

I have always been under the impression that manifold vacuum will differ very little from ported vacuum except at idle. I think you get high vacuum at idle and light throttle and low vacuum at or near wide open. I use manifold vacuum on my 2.0 to make it a little friendlier at idle without having to use too much initial advance. It doesn't like to idle without a lot of timing because I have a higher than stock duration cam and low compression. The easiest way to get the idle timing I need with an acceptable total advance is to use close to stock initial advance, vacuum advance at the manifold, and stock mechanical advance.

I could achieve the same results with ported vacuum advance, increased initial advance, and a modified mechanical advance. The reason I run it the way I do is that for one, it runs well and doesn't ping, and for two, I have not had my distributor apart yet with the intent of modifying the mechanical advance, and do not know how difficult it may be to do so. I have an extra distributor that I plan on playing with eventually, but I'm not in an awful hurry as the engine seems to run well as it is.

 

[Mark_88]

^^ Me too...I tried playing with the carb vacuum and was not impressed with the results...but maybe I had it on the wrong port...there are only two on this carb...so odds are pretty good at hitting the right one first time...lol...

My truck does run good too using manifold vac...and I've played with the adjustments quite a bit...

Most recent discovery was that on the valve cover side of the carb there is a secondary fuel mixture screw...I had, for some reason, turned this down (I think because I found it hanging out of the port) and when the secondary opened it was sort of bogging...when I adjusted this up the engine performed a bit better near the higher end (DOH) but fuel economy has gone down some (DOUBLE DOH!)...

 

[Mikel89us]

First off, the 2.3 loves timing advance. The electronic distributor on the EFI's does its best work at 20 deg base timing.

Second, ported vacuum is at 0 at idle, and wide open. It is meant to give more advance at part throttle where it is most beneficial. you dont need it at idle because you dont need power. and at WOT the higher cyl pressures make the need for more timing go away. Trust me when i tell you that ported vacuum is the best for power AND efficiency.

 

[upnsmoke]

Mike, manifold vacuum is 0 at wide open, same as ported, and high at part throttle/ cruise, also same as ported, which should make vacuum advance perform similarly at all conditions other than idle whether manifold or ported vacuum is used. The only reason I use manifold vacuum on my engine is so I do not have to run too much initial timing. I need at least 15* initial advance to make my engine behave around idle, which is 5* over stock. I don't know what total advance that nets me, but I imagine it would be around the max I would want to run. I have a known good distributor I plan to put in tomorrow, so I will know a little more then. If I find that I can run enough intial timing to keep the engine happy without going too high on total timing I may give ported vacuum another try. I also intend to disassemble my extra distributor to see if anything can be done to change the total advance reasonably conveniently.

The only concern I would have with running manifold vacuum as opposed to ported would be if the carb, an adaptor plate, or something in the intake became a restriction at high rpm, causing vacuum to rise and timing to increase, even at WOT. That would not be a concern with ported vacuum. It is not a problem on my current setup. I can't think of any other particular disadvantage of using manifold vacuum. Come to think of it, I did hear someone theorize that going from idle to WOT could cause a temporary, coinciding operation of vacuum and mechanical advance, if the vacuum advance was slow enough to retard from its idle position, but I'm skeptical of that one.

 

[upnsmoke]

rab, I don't mean to derail your thread. I'll start my own when I get some actual advance numbers to discuss. In the mean time, Mike, how much total advance do you think I should run? I have 218 duration intake and exhaust, and my head decked .01.

 

[Mikel89us]

Valve overlap has a bigger effect on it than duration. But given that its probably 110 0r 108 its going to have less dynamic compression ratio, unless you have the cam timed. If i were you i would set it at 20* base, with ported vac. Try it for a few days, if you get any spark knock just back it off 1* at a time untill it goes away.

 

[upnsmoke]

I don't have that much cam. I figure overlap is only about 42*. That is still quite a bit of cam for a 2 liter. I'm just figuring I can get away with more total timing than a stock cam, stock compression engine. I didn't get a chance to play with it today, but I want to see exactly how much mechanical advance it gives me and when. What I really need to know is how much mechanical advance I can get away with before it pings. I'll start a thread to discuss some numbers. Hopefully I will have something tomorrow.