Sanity Check, please. 250 six, auto, stock. Starts fine. Fast idle OK. Acceleration OK too. Idle when warm is.......crappy. It will idle OK and then stumble and miss. When I put it in reverse it is rough. Bump it in nuetral and up the idle and it smoothes out. When I first got the car the idle was too fast. Was this one way to mask the rough idle? I thinking the idle circuit has a piece of crap floating around. Is it time to be boiled? Thanks in advance. jacka
Problems like this is usually general tune up problems. Make sure that the car has the correct idle speed, if it is set too low when warm, that can cause it. Make sure the idle mixture screws on the carb are set right, make sure the timing is set correctly, and give it a decent tune up. Very importantly, make sure the points are set right. One of the easiest things I have found to work on a set of points is a match book cover, it is just the right thickness. Provided you have no vaccuum leak this will fix your prob. (you might be due for a carb rebuild)
i have the same engine and the same problem everybody i talk to and ask about it they tell me the same thing that is just the way the engine is... i dont know if that is true but its what i hear still to this day it misses and stumbles i dontknow what causes it though
Make sure the choke is coming off (open) when the car gets warm. If it is an electric choke, make sure you are getting power to the "clock-spring" choke housing. This sounds similar to what mine did once--wire to choke was broken and choke was staying on, running way, way too rich. Good Luck.
....Hello Jack, I don't have the answer to your problem but want to say for all, that the engine emissions setup thru these years to 77 take many different forms. .... ....There are all kinds of vac and temp switches controlling the vacuum advance to the distribitor. ....Basically I feel your problem can be in two areas, the ignition advance and pump shot in the carb. You may also take a look at the mechanical advance weights for sticking and if a dual vac diaphram, for a problem , using a hand vac pump to test .....Then there is the EGR valve operation. If the valve is open , rough idle will result. It's only supposed to open during cruise with the system allowing some advanced ignition timing at the same time. ....To get the system tested calls for the service info on that setup. I now have nearly all the books on the Ford systems. ... ....Volume 6 is the book that has all the hose routing for all the engines. ...Without any info, I would temporarly connect a hose from a (ported) carb location directly to the dist. to see if it helps off idle stumble. If so, its a good bet that the system isn't allowing enough vac advance. It would become a matter of finding the problem or working around it if allowed. A timing lite would also be helpfull in seeing what is happening. ....Fuel injection actually has all the same actions going on, but done with computer control decisions, sensors and actuators. It's eaiser to work on because the ECU will store codes to point to what part of the system is causing a problem. ....If the system can be id-ed close enough, I can see what is involved for you. The systems differ for A/C, non A/C, geographic location etc. Many are in a struggle with these systems and makes for some unhappiness. ....If i can help further, give a hoot.
Thanks to all for your responses. I'll have plenty to check out. Vaccuum pump, timing light, feeler guage, etc. and off I go. jacka
Well as long as we are adding our "guess", I'll put mine in. I see people using the same carb gasket and spacers over and over.... they crush and develop leaks. That is where I look. I can idle my 6 down to 450 rpm and still smooth. Just need to make sure their are no leaks.
The above stuff is definitely all great things to check out. You may also develop a problem that I incidentally had, which is that my actual carb was cracked. So there was a crack in the top part of the crack that was sitting right on top of the gasket and my mechanic showed it to me by pointing to the spot where it was sucking in some WD40 when he would spray it on there. Don't think this is a VERY common problem but just hoping my misfortunate will maybe help
Help! Hey, I´ve been far from here for a while and just saw this today. I have a 1976, 4 door, 250 ci L6 engine and a c4 tranny, no A/C, no brake assist... well, a man´s car, hehehehe. I have the same problem, checked for leaks and found no one, changed sparks (set at .042" clearance like the spark plug menufacturer manual said), change the spark cables, change the rotor and distribuitor cap, cleaned the carb and change the carb kit (rebuild) and calibrated correctly, (all of that was needed) used a timing light (set the advance at 6º BTDC, could anyone help to check if that ignition timing is right? ) and the failure is the same, when warm the idle is carppy, tumbles, misses, etc. I´ve found that using the timing light when it fails the light appears some times after and sometimes before the mark, like it advances or retards the timing. It happens even with the distributor vacuum line disconnected. Can it be the mecanical advance? When in drive or reverse or any speed applyed the engine even turns off. I hope all of this info help you to help me... hehehehe. Thanks in advance.
Carburator My mav's 250 L6 is working on a Carter RBS carburator, what is your opinion on that carburator? I've been reading and it seems to be not the most liked one. I've heared the same phrase "it's just the way that engines are" but i'm not happy with that. What calls my atention is that the fail is not "rythmic" or constant, is unregular or not periodic, that only fails when is warm, and that my engine were so quiet some time ago... so, that's not the way my engine is. Can you give me some help, please...? I've benn checking on the posible causes you wrote before, but i keep without finding that fail source. My car give me headaches mostly on traffic, at 85 MPH runs just fine. (I run at least 86 miles a day on that speed)
if you are still working it let me know i am in thornton may be i could take a look see my E-mail is bpcotton@msn.com
