I'm having some trouble with my 72' Maverick - at high speeds (55+) when the transmission should be kicking into 4th it seems it refuses to catch in gear... the car shudders and doesn't respond no matter how the throttle is manipulated. Occasionally the engine will kill if I try too hard to coax it into gear. Some notes: Flooring it doesn't prompt a change into a lower gear or into 4th, nor does fluttering the pedal, or easing back and coasting. The tachometer (aftermarket) doesn't indicate a change in RPM when I work the pedal - it stays roughly at about 2700-3000. It doesn't do this constantly - only when the acceleration to 4th gear isn't consistent. Flooring it all the way to 4th or easing up on it will work just fine at least 80% of the time. Carburetor (aftermarket Edelbrock) is running rich and needs adjustment; I suspect that this may be a large contributing factor. Due to the my unfortunately pathetic knowledge of transmissions I'm stuck on how I should diagnose and fix what's going on. Any suggestions?
Well first off all what transmission do you have? Mavericks never came with four speeds so we kinda need to know whats swapped in there.
I am going to say that if you have a four speed automatic it is an AOD. A rich running carb has nothing to do with the way an AOD shifts. The shifts are controlled by the governor, line and throttle pressures. The one thing that must be set perfectly in the AOD is the throttle pressure. Too low and it will slip the frictions and burn up. Too high and it will not shift when it should. There are actually four changes in rpm with an AOD: 1-2 shift; 2-3 shift, converter lockup; and finally Overdrive. If you have stock rear gears in your car the by the rpm I would say that you are only getting to a point where the converter is locking and you are not going into OD at all. Fluttering is usually the converter lockup failing.
This sounds like the most likely culprit based upon what little I can tell about it, but I'll continue to look into it. Thanks for all the advice, guys.
