The yellow '76 Maverick has a 200 in-line 6 engine. The car was running very rich and sometimes stalling. I pulled the carburetor and had a mechanic install a carb kit. It ran much better, but was still not quite right. I drove the car to the same mechanic to have him fine tune the carb and check the timing. When I picked the car up, he said that he has worked on many of these I-6 engines and they never run completely "smooth". After the adjustment, the car seems to run well at highway speeds, but it idles a bit rough, and when I come to a stop sign, it almost seems like it's going to stall. I had a couple of friends (who know more about engines than I do) listen to it, and they said that it sounded like it was starving for gas when idling. One guy said that he thought perhaps one of the ports may be partially blocked, and the mechanic may not have cleaned/soaked the carb good enough. 1.) First, it is a common characteristic that the straight 6 engines idle a bit rough? 2.) Any suggestions as to what I should be checking for? Could the problem be a sloppy carb kit install?
Yes, it seems that many of the sixes idle rough. I find it to usually be in the carb. I have a 76 250 with a 2 barrel conversion (from a pinto/mustang II) and it idles very, very smooth. If you're tired of the old carb, you might try doing a 2 barrel conversion. There are adapters out there.
Inline sixes have fuel distribution problems. The end cylinders don't get the same amount of fuel as the two in the center. Short of installing multiple carbs, it's an unfixable problem.
Thanks for the insight, I've never had one, so I don't have any experience to draw from. I was just wondering if the mechanic was feeding me a line of bull or not.....
Forgot to say that direct port fuel injection solves the problem also. That's why the 4.0 in Jeeps performs so well.
could be plugs...check them(if your carb was runnin rich your plugs could be carboned up), might have a slight wobble in your vacuum advance plate(had the washer and clip come off mine...boy was that a fun ride home) basic maintenance...plugs, cap rotor, pull the cap and check your rotor for corrosion, also check the cap for corrosion, check your points as well for corrosion, and your point gap(if you dont know how to do this, take it to your mechanic and have him go over them for you)
Before I took it to the mechanic, I changed the plugs and the wires (and actually both looked good already. I did not change the rotor cap. From the outside, it looked fairly new, but I'll get a new one anyway, just to be sure. Could the EGR valve be part of the problem as well?
theres 2 parts...the cap and the rotor, you can't tell from the outside, i thought the guy replaced mine when i got my car, turns out it was the source of all of my problems. i dont know how the egr valve works seeing as how i dont have one, gl with it
Both the 250 and the 200 I have had and have now ran rough at an Idle. The 200 in mine now lopes like it has a cam in it and the carb has been overhauled as well. I think if I ever get around to it and take my time I could smooth it out a little but it almost never actually cuts off (once in a while when I first start it and back out my grandmothers drive way it cuts off, but other than that it just runs rough. It also completely changes idle when the A/C is on, still runs rough but has a different cadence to it. I just let it along and let everyon think it is lopping like a V8.LOL
Regardless of ones interpretation of 'idle smooth' or 'idle rough', the engine should NOT "seem like it wants to stall when you come to a stop". There is more tuning work to be done whether you go back to the mechanic or find someone new.
It is a simple matter of tuning. Check the compression, warm. Set the dwell and timing to make sure you have a decent starting point. Set the mixture screw to 1 1/2 turn out. Set the idle speed (with the curb idle solenoid disconnected if it has one) at 550 to 600 in neutral). Connect the curb idle solenoid, start the engine, set the park brake and block the wheels. adjust the idle using the curb idle solenoid to 700 (in drive). Adjust the idle mixture to get the highest idle speed. Reset the speed with the curb idle solenoidto 700. Readjust the mixture for the highest idle you can get. If there is no change with the mixture screw then set it at 1/8 turn richer than the best idle. Put the car in park, unblock the wheels and test drive it for twenty minutes. Correct any problems that you find in the test drive - you may have to increase the idle speed to 750 - if so then readjust the mixture screws. Once it is running where you want it put a drop of "After-Torque" by Loc-Tite on all of the screws that were adjusted. The Idle speed screw, the curb idle screw, and the mixture screw. The next morning start it and run it cold for twenty minutes. If the choke comes off with no problem and the engine runs well during the transition from cold to warm then you have it.
every inline 6 maverick i had didnt idle right either, i hate inline 6 motors, might like em better if they were injected
Hey Paul, Sounds like you have it down to a science, and a lot of what you said it over my head, lol. Man, if you were closer to me, I would drive it over and have you take a look! I'm going to take it back to the mechanic who worked on it originally today and see if he can't get it right. If not, I'll be trying the tips that a lot of my fellow Maverick/Comet members suggested. Thanks everyone for your help, I really appreciate it! I'll keep you posted.... Art
True. Stalling and idling rough are two different things. Back to my last post, the 2 barrel carb really did make the six idle like I've never heard it before. It's really smooth and consistent. I was impressed. But Paul is right, with the right tuning it should run good. Ford didn't sell the six with rough idle.
