727 rebuild guide....

[Yatzee]

This is just a thought but a possible reality concerning your transmission issues. Some 727 had an issue where both bands would momentarily engage on up shifting causing a hard 2 to 3 gear shift. The issue was addressed by backing off the band adjustment to delay the overlap. This had been addressed in other ways by reducing fluid passages and removing the spring from the main servo and replacing with a solid rod. I have rebuilt several of these units and usually end up trashing the shifter valve body because this is one area of "spool to bore" wear which can result in fluid leaking by. I have found that an inexpensive alternative to the original valve body is one made by TCI witn an incorporated improved shift kit. $225 comes to mind but price varies. Not saying that this is your exact problem but over the years these units do tend to wear and leak by. As you are aware a good master kit should include quality parts for a complete rebuild except those pertaining to the shifter control unit. Surging actually sound like uneven or low fluid pressure ( or cavitation ) or the result of fluid not reaching the required pressure to hol the servo's during actuation, hence the bands start slipping. Just a few thoughts but in reality you will have to test the pressures at various points with the engine running and someone manipulating the shifter. The manual shows exactly how to do this to narrow down the problem.

 

[thrashingcows]

This is just a thought but a possible reality concerning your transmission issues. Some 727 had an issue where both bands would momentarily engage on up shifting causing a hard 2 to 3 gear shift. The issue was addressed by backing off the band adjustment to delay the overlap. This had been addressed in other ways by reducing fluid passages and removing the spring from the main servo and replacing with a solid rod. I have rebuilt several of these units and usually end up trashing the shifter valve body because this is one area of "spool to bore" wear which can result in fluid leaking by. I have found that an inexpensive alternative to the original valve body is one made by TCI witn an incorporated improved shift kit. $225 comes to mind but price varies. Not saying that this is your exact problem but over the years these units do tend to wear and leak by. As you are aware a good master kit should include quality parts for a complete rebuild except those pertaining to the shifter control unit. Surging actually sound like uneven or low fluid pressure ( or cavitation ) or the result of fluid not reaching the required pressure to hol the servo's during actuation, hence the bands start slipping. Just a few thoughts but in reality you will have to test the pressures at various points with the engine running and someone manipulating the shifter. The manual shows exactly how to do this to narrow down the problem.

I did think about possible line pressure being off, but had no idea how that would effect the transmissions function. Thank you for your insights!

 

[70bigblockdodge]

Did you mess with the pump at all. It may have a pressure regulator or a low pressure condition (scored rotors or housing ) this is my guess as it only does it when hot. Also your cooler setup is backwards should go through air cooler first and rad cooler second, however being as most of these cars are only fair weather drivers you are okay I would say. This is only a opinion take it for what is is worth.

 

[thrashingcows]

Did you mess with the pump at all. It may have a pressure regulator or a low pressure condition (scored rotors or housing ) this is my guess as it only does it when hot. Also your cooler setup is backwards should go through air cooler first and rad cooler second, however being as most of these cars are only fair weather drivers you are okay I would say. This is only a opinion take it for what is is worth.

The pump was looked at, and there was no scoring....it was in darn near new condition. So doubt that it would be that. But thank you for the suggestion.

As for the routing...I have seen it said that the routing of the coolers should be the other way...but I have seen it said it should go the way I have it hooked up as well. To me it doesn't make sense to go the other way. Rad is running 180-195 degrees....so it cools the fluid as it passes through, but the air to hyd would cool it even more since it is already cooled down from the water to hyd cooler. The air to hyd cooler would be much cooler then the rad, since it's in front of everything and is pulling cool air from outside the car.

 

[70bigblockdodge]

They don't want it to run too cool, steady temp on hydraulic system is best but like I said fair weather cars I think it is okay. Hope you sort that out.

 

[thrashingcows]

Well I don't think it's the tranny. Was talking with a friend of mine who is good friends with a guy who has been rebuilding 727 for over 30 years. he described my problem and he flat out said it is not the tranny. Nor could it be the valave body. He said in 30 years of rebuilding these 727's he has replaced, or had failed exactly zero valve bodies.

We believe it is Carb, fuel, ignition related. I did go out and replace the electronic ignition module...did not make a difference. But then I noticed that my carb was loose...like really loose! So tightened down the bolts and the car is running a bit better, still stumbling when it gets hot, but not as bad and does not eventually stall the motor.

 

[73Coupe]

I finally had a chance to read this one cover to cover. I appreciate all the work you've put into this thread. Any update on the engine issues? It sounds like it could be fuel related....possibly vapor lock since it only happens when hot. Or, like you said, the carb. Sticking needle valve, etc. Hope you get 'er figured out!

 

[thrashingcows]

I finally had a chance to read this one cover to cover. I appreciate all the work you've put into this thread. Any update on the engine issues? It sounds like it could be fuel related....possibly vapor lock since it only happens when hot. Or, like you said, the carb. Sticking needle valve, etc. Hope you get 'er figured out!

Definitely not tranny related. I have swapped electronic ignition module, bit better, found loose carb bolts...tightened back down, and replaced fuel filter, bit better again. Then I pulled intake and swapped on a new Eddy performer...way better, had bad intake gasket on the exhaust cross over, and potentially a couple other intake ports?

So motor is running way better, barely perceivable stumble at full operating temperature.