Motorcraft 2100 Carb Adjustments for 302

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M

Machman

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Location
NY
My Car
1971 Mach 1
When I started the car today I noticed the motor was running irregulary so I tried to adjust the 2 screws in the front and got it all out of wack,

it looks like poor running is still a fuel pump problem so I need to reset the 2 screws in the front correctly

Can someone post a real easy static adjustment for the two front screws?

Something like turn both screws all the way in untill closed then back them out such and such many turns, etc

 
3 turns usually implies 1.5 complete revolutions: that is the convention for starting the tuning of the idle circuits. Put a tach on the car (or use a vacuum gauge) and adjust each screw one at a time until the curb idle speed (or vacuum) maxes out. Adjust idle rpm back down to 650-800, depending upon your wishes, and adjust once more. Usually, turning one of the screws one way or the other makes the engine run just a touch rougher.

 
Thanks midlife , caspianwendell -

did you mean 3 complete turns? aka top slot of screw head does a complete rotation to be on the top again = 1 turn

or

rotate screw head untill bottom of slot is rotated to the top = 1 turn


I did it by 3 complete rotations aka top of screwhead is on top again - 1 rotation

I noticed the car idled then raises rpms , then lowers rpms signifing lean mixture or vacuum leak.

I have a dual distributor and dis connected and plugged all the vacuum lines,

I have the vacuum line from the side of carb going to the part of the distribitor with the big diaphram chamber on it.

Is this correct or should it go to the front?

 
Last edited by a moderator:
Thanks midlife , caspianwendell -

did you mean 3 complete turns? aka top slot of screw head does a complete rotation to be on the top again = 1 turn

or

rotate screw head untill bottom of slot is rotated to the top = 1 turn


I did it by 3 complete rotations aka top of screwhead is on top again - 1 rotation

I noticed the car idled then raises rpms , then lowers rpms signifing lean mixture or vacuum leak.

I have a dual distributor and dis connected and plugged all the vacuum lines,

I have the vacuum line from the side of carb going to the part of the distribitor with the big diaphram chamber on it.

Is this correct or should it go to the front?
Click to expand...
All vacuum lines should be connected.

Most people refer to a "full turn" as the top of the screwhead goes to the bottom. To me, a "full turn" is when the top of the screwhead returns to the top. For carbs, the starting point is to go 360* rotation, plus another half-turn (180*). That gets you close. Then adjust screw in one direction: it typically will either get worse (then go in the other direction), or get better then worse. Find the best position. Best position is highest and smoothest rpm.

 
[/size]

Thanks midlife , caspianwendell -

did you mean 3 complete turns? aka top slot of screw head does a complete rotation to be on the top again = 1 turn

or

rotate screw head untill bottom of slot is rotated to the top = 1 turn


I did it by 3 complete rotations aka top of screwhead is on top again - 1 rotation

I noticed the car idled then raises rpms , then lowers rpms signifing lean mixture or vacuum leak.

I have a dual distributor and dis connected and plugged all the vacuum lines,

I have the vacuum line from the side of carb going to the part of the distribitor with the big diaphram chamber on it.

Is this correct or should it go to the front?
Click to expand...
All vacuum lines should be connected.

Most people refer to a "full turn" as the top of the screwhead goes to the bottom. To me, a "full turn" is when the top of the screwhead returns to the top. For carbs, the starting point is to go 360* rotation, plus another half-turn (180*). That gets you close. Then adjust screw in one direction: it typically will either get worse (then go in the other direction), or get better then worse. Find the best position. Best position is highest and smoothest rpm.
Click to expand...
Thank you and I adjusted it the way you suggested and it starts again but still runs rough and uneven aka up and down in revs, so I thing there is a possible vacuum leaksize]







Sounds lean to me. try at least another 1/2 revolution, maybe a bit more. Do you have a vacuum gauge? This diagram may help with the hoses. http://mustangbarn.com/images/vacs/71%20351C%202v%20with%20dvcv.gif Chuck
Click to expand...
 


Hi Chuck ;

 


I checked and saved a ton of diagrams from the site but none are exactly like the one in my car. I heard the 71s could be tricky as alot of expiermenting was done.

 


I reconnected both dist vacuum hoses back on , one to the side of carb one to vacuum port on rear of engine and am pretty sure both are correct.

 


I initially connected the port in the rear of the carb body that activates the carb plunger on top that opens the choke during higher rpms to the transmission metal tube vacuum line but realized it was wrong as when I ran the car it sucked and the plunger on the choke was conmtinuosly down.

 


I figured it belonged connected onto the rear vacuum intake terminal as well so it would only activate the choke plunger on hard driving.

 


If not connecting vacuum to the metal trans tube where are some places that tube vacuum line should go?

 


AJ







Have you got a vacuum guage? If so, you want to adjust both sides, so that you get the highest number in inches, of vacuum, at idle..
Click to expand...
 


Thank you for the reply but sadly I no longer have one as I connected it to a previous car I had and it went when I sold the car, I'll see if I have another somewhere

 
Last edited by a moderator:
If the engine has an EGR look at the diagrams for 72 california only and 1973. These came with an EGR from the factory. Chuck

 
If the engine has an EGR look at the diagrams for 72 california only and 1973. These came with an EGR from the factory. Chuck
Click to expand...
Thank you Chuck,

I figured out that the transmission tube should not be connected to anything its to bring fresh air to the trans and needs to be open to air.

I was told by a parts guy at auto pro who works on old motors that the egr connects to the vacuum port with all the other lines.

 
Last edited by a moderator:
If the engine has an EGR look at the diagrams for 72 california only and 1973. These came with an EGR from the factory. Chuck
Click to expand...
Thank you Chuck,

I figured out that the transmission tube should not be connected to anything its to bring fresh air to the trans and needs to be open to air.

I was told by a parts guy at auto pro who works on old motors that the egr connects to the vacuum port with all the other lines.
Click to expand...
If the small diameter transmission tube ends at the rear of the intake manifold it is the line to operate the vacuum modulator on the transmission. If we are talking about the same thing, it must be connected or the transmission will not shift properly. Chuck

 
Hi Chuck; Here is a picture of the tube , it is the one w/ the hose that loops onto the vacuum block.

It is presently open to air as per the auto pro guys suggestion, is this the tube that should be connected back to the vacuum block?

 
Last edited by a moderator:
Hi Chuck; Here is a picture of the tube , it is the one w/ the hose that loops onto the vacuum block.

It is presently open to air as per the auto pro guys suggestion, is this the tube that should be connected back to the vacuum block?

IMGP0141.jpg
Click to expand...
Mike, I'm struggling with an answer based on the picture. The steel line seems to be too big and in the wrong place to be the line to the modulator. It could be the line that is supposed to go to the carbon canister located beneath the passenger side hood hinge (blue and round). If it is someone has reshaped it (bent it forward). The clear plastic line seems to go down towards the transmission. Follow it to see if it connects to the modulator on the rear of the transmission. If it does, replace it with fuel and oil rated automotive hose. The hose for the modulator should be connected to manifold vacuum. Sorry I'm not of more help. Chuck

 
I was told by a parts guy at auto pro who works on old motors that the egr connects to the vacuum port with all the other lines.
Click to expand...
I would disagree with your parts Guy. On cars with egr ( mine is one) there are ported vacuum switches that manifold vacuum routes to then the egr connects to a leg on the vacuum switch. You should have a vacuum diagram sticker under the Hood or contact Don at OMS for a new one. This will show the proper routing for your vacuum lines.

 
Hi Chuck; Here is a picture of the tube , it is the one w/ the hose that loops onto the vacuum block.

It is presently open to air as per the auto pro guys suggestion, is this the tube that should be connected back to the vacuum block?

Mike, I'm struggling with an answer based on the picture. The steel line seems to be too big and in the wrong place to be the line to the modulator. It could be the line that is supposed to go to the carbon canister located beneath the passenger side hood hinge (blue and round). If it is someone has reshaped it (bent it forward). The clear plastic line seems to go down towards the transmission. Follow it to see if it connects to the modulator on the rear of the transmission. If it does, replace it with fuel and oil rated automotive hose. The hose for the modulator should be connected to manifold vacuum. Sorry I'm not of more help. Chuck
Click to expand...
Hi Chuck;

 


The plastic hose you see is just a loop of hose I used to close off 2 open vacuum connections so they are not open to air.

 


The steel tube goes down to the trans, the blue cannister already is connected to a different metal tube coming from the gas tank

 


I just saw another pic on the web of a 302 and the same tube is connect to vacuum port so I will connect it there based on what you said and the other pic I saw

 


AJ
Click to expand...
 
Last edited by a moderator:

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