inline 6 running rich

[BorderBronco]

I recently dropped in a petronix unit on my 1970 I6 and while i was at it changed the plugs out since it was running rough before. It ran great after it warmed up. After 1 trip around town it was back to running rough. Pulled the plugs and they have very heavy carbon build up on them and you can smell it running rich. I have checked the idle mixture screw and idle speed screw. on the carb it has the dial that shows which way to dial in lean. Never really have messed with it. Never messed with them on the two 302's we have either. will running the dial to more lean or away from lean help any? Dad and i were talking and we dont know when the carb was last rebuilt. Says Carter YF on it. I have some pics of the carb if anyone wants to point me in a good direction.
(Personally i think she's jealous of the other two Broncos that recently were adopted into the herd. )

 

[broncnaz]

When its fully warmed up check the choke plate it should be straight up. If its not then you can adjust the black choke housing until the choke plate is fully open.
Several other things can cause the rough running/rich condition. 1. is ignition timing you may want to recheck it and start off with the stock setting. 2. misadjusted carb. 3. float level to high. 4 carb is gummed up inside and needs a rebuild.
Just keep in mind that anythime you adjust the ignition timing you will probably need to rreadjust the idle mixture screws and the idle speed.
I'd suggest rebuilding the carb it doesnt cost much and you can learn a little while doing it.
You may also want to make sure your pertronix is hooked up correctly.

 

[BorderBronco]

When its fully warmed up check the choke plate it should be straight up. If its not then you can adjust the black choke housing until the choke plate is fully open.
Several other things can cause the rough running/rich condition. 1. is ignition timing you may want to recheck it and start off with the stock setting. 2. misadjusted carb. 3. float level to high. 4 carb is gummed up inside and needs a rebuild.
Just keep in mind that anythime you adjust the ignition timing you will probably need to rreadjust the idle mixture screws and the idle speed.
I'd suggest rebuilding the carb it doesnt cost much and you can learn a little while doing it.
You may also want to make sure your pertronix is hooked up correctly.

Thanks for the info. I went back and looked at my Petronix and all connections are good.
I will look at rebuilding carb next.
Stupid question but was searching for rebuild kits, what info off the carb do I need?

 

[broncnaz]

Did you make sure the pertronix was hooked up to a full 12 volts? you really cant run it off the orginal coil wire.
Im not 100% on what numbers you need off your carb but I'd take any number off it you can find. Most likely you wont need the numbers as most carb kits fit a lot of different carb part numbers. you should be able to just tell them the year of the bronco and its a carter YF the kit should fit. bad thing is someone stuck a autolite tag on your YF carb. So dont use the numbers off that tag as they will be for a autolite 1100 carb.

 

[BorderBronco]

Did you make sure the pertronix was hooked up to a full 12 volts? you really cant run it off the orginal coil wire.
Im not 100% on what numbers you need off your carb but I'd take any number off it you can find. Most likely you wont need the numbers as most carb kits fit a lot of different carb part numbers. you should be able to just tell them the year of the bronco and its a carter YF the kit should fit. bad thing is someone stuck a autolite tag on your YF carb. So dont use the numbers off that tag as they will be for a autolite 1100 carb.

I hooked the Petronix to the positive side of the coil. Wish i had a pic but negative went to where old negative hooked in, then positive on the positive side and then there is the line coming from coil to top of dizzy. You think it should be tied directly to full 12v like direct to battery?

 

[MPG_Bronco]

sadly there is nothing you can change by screw on that carb, you haev to change the jet it self, meaning taking it apart and swapping jets, which are hard to find

those carbs are meant for a 250ci, and IIRC I think you have either the 170 or a 200ci. either way it's tuned for a bigger engine. best thing to do is take the jet out, get a small guitar string, and put it thorugh the jet when you put the jet back in, this will restrict the gas flow.

another thing you can try, is advancing the timing, the i6 engines LOVE STATIC timing!!!!
my old 200ci in my mustang loves 19* static timing with a total of 36* at 2500rpm. yours in stock form, the vacuum is too agressive, limit the travel of the vacuum advance, then bump up the static to 12* that's the best you can run on a stock i6.

Check out the I6 forum for more tuning, www.fordsix.com/forum , best place for all tips/trick on that i6.

 

[broncnaz]

You have to make sure that you have a full 12volts to the pertronix box. now if you used a pertronix coil too then you can run a full 12volts to it as well and hook the box to the coil for its power. but most other coils need a lower voltage like the stock coil wire gives. basically if you need to run a hot wire from the ignition switch to the pertronix box

Carter carbs were used on broncos so unless a part number is verified saying it came off a larger engine it will work. Even then jetting is not all that different. it should stillbe able to idle smooth just may run rich during cruise RPM's.

 

[tatersalad]

If the carb is adjustable you put a vacuum gauge on a port with full vacuum. start the engine, screw the jets or jet all the way in and then slowly turn them back out until you get the most vacuum on the gauge. with two jets you start with either one and then move to the other, after you have adjusted them both individually you go back and forth just slightly to see if you can get a little more vacuum... hope that helps

 

[BorderBronco]

Thanks guys. I will be trying the different suggestions. I will look at the voltage on the Petronix too.