Rebuilt 727 Giving Me a Headache

[Mason]

My converter stall is 1800 and I have the original rear-end gears still from when it had the original 318, I'm not sure if it would have much to do with the sluggish feeling. I spoke with a guy that was knowledgeable about Mopars and he told me about needing lower gears and a much higher stall to get it working right...any insight on this? I would just expect my car to still be able to break the tires loose with a low stall converter and original gears.

 

[Dipstick]

If the front band was too tight it would be sluggish in first because it would be partially in second but it would feel normal in second and then sluggish in third. Both bands too tight could cause it to be sluggish in all gears.

Only way to find out is to properly adjust both bands.

 

[mopar 3 B]

To tight rear band could put it into reverse and first at the same time. Just like locking two gears in a manual. Eventually the weaker will give up. A power flow chart could clear this up.

 

[Mason]

If the front band was too tight it would be sluggish in first because it would be partially in second but it would feel normal in second and then sluggish in third. Both bands too tight could cause it to be sluggish in all gears.

Only way to find out is to properly adjust both bands.

Have you seen cars act like this when the bands are too tight? It would make sense considering it feels like the brakes are being applied.

 

[mopar 3 B]

To tight rear band could put it into reverse and first at the same time. Just like locking two gears in a manual. Eventually the weaker will give up. A power flow chart could clear this up.

Have you seen cars act like this when the bands are too tight? It would make sense considering it feels like the brakes are being applied.

No never had one do it. Unfortunately the pan has to come off to check the rear band.

 

[Superbeedad]

What does it do in reverse?

 

[Superbeedad]

Does the engine rev up in 1st gear or does it lug. Does it do the same in reverse? If the converter is locked up the engine would lug. If the converter is fine and the transmission is dragging somewhere the engine will rev through the torque .. like doing a brake stand.

 

[Mason]

To tight rear band could put it into reverse and first at the same time. Just like locking two gears in a manual. Eventually the weaker will give up. A power flow chart could clear this up.

No never had one do it. Unfortunately the pan has to come off to check the rear band.

I'm going to go drop the pan tomorrow and adjust the rear band and then the front one, hopefully I get a result.

 

[Mason]

Does the engine rev up in 1st gear or does it lug. Does it do the same in reverse? If the converter is locked up the engine would lug. If the converter is fine and the transmission is dragging somewhere the engine will rev through the torque .. like doing a brake stand.

To make it more clear, my engine doesn't rev up to high rpm at all when in any gears. When I push on the throttle it feels as if I have the brakes applied its so sluggish. However when I'm in park or neutral it sounds like its going to pick the wheels of the ground when I give it gas. In all honesty it feels like I have 50 hp...its ridiculous how slow it is. Could my bands still be too tight? Valve body issue? Converter problem?
Mason

 

[Kern Dog]

I had a trans act like this years ago. It felt like the converter was TOO loose though. When I tried to accelerate, the engine revved up and the car moved but it felt strained. Like you, the rpms seemed to build much slower than in neutral.
They just exchanged the trans and later, I mean weeks later, I heard that the trans was completely fried inside.
Not trying to dump doom and gloom on you here, this is just my experience.
Also, 1800 is a really low stall speed for any muscle type car. A stock 340 or 383 4 barrel car was rated over 2000, the 426 Hemi was 2350 according to a service manual I read. Add in any bigger cam and the stall speed needs to be increased.
Axle gearing is another issue. The standard ratio for a 340 4 barrel or a 383 4 barrel was a 3.23. Again, if you have a bigger cam, the gearing needs to be stepped up as well.
Using a low stall converter and a 2.76 axle is like letting out the clutch (IN a manual trans) at idle in 2nd gear and flooring the gas pedal. It will eventually move but it takes a while to get there.

 

[Mason]

I had a trans act like this years ago. It felt like the converter was TOO loose though. When I tried to accelerate, the engine revved up and the car moved but it felt strained. Like you, the rpms seemed to build much slower than in neutral.
They just exchanged the trans and later, I mean weeks later, I heard that the trans was completely fried inside.
Not trying to dump doom and gloom on you here, this is just my experience.
Also, 1800 is a really low stall speed for any muscle type car. A stock 340 or 383 4 barrel car was rated over 2000, the 426 Hemi was 2350 according to a service manual I read. Add in any bigger cam and the stall speed needs to be increased.
Axle gearing is another issue. The standard ratio for a 340 4 barrel or a 383 4 barrel was a 3.23. Again, if you have a bigger cam, the gearing needs to be stepped up as well.
Using a low stall converter and a 2.76 axle is like letting out the clutch (IN a manual trans) at idle in 2nd gear and flooring the gas pedal. It will eventually move but it takes a while to get there.

Hey Kern Dog, I'm glad someone else has had the same issue (can't find anyone else who does lol) and yeah im searching for a dana 60 to put in the back with 4.11s when i can get the chance. As well as the converter too it, the list never seems to end haha. Did they explain to you what was making your trans do that? I feel like there's got to be a culprit somewhere. I really hate to have to pull my trans out.
Mason

 

[Mason]

It’s not the bands. Take it back to who built it. The converter could be bad. But u do need a higher stall and better gearing. U may also have motor problems also. The tune could be way outta wack. Kim

I doubt my engine is out of tune to be honest but I do think it definitely has something to do with the power not transferring correctly. I might look for q B&M high stall converter to call it a day, unless I have to pull this tranny out and trash it.

 

[Superbeedad]

Here’s a good reference on the lockup clutch. Personally I think it’s locked up. The valve body went through some changes as per article but all has to match up. https://www.allpar.com/mopar/transmissions/lockup.html

 

[Superbeedad]

....if it is locked up the car should still accelerate but very slowly until reaching a highway speed. If the car can’t gain any speed at all or can’t move, then something likely dragging in the trans.

 

[Mason]

Here’s a good reference on the lockup clutch. Personally I think it’s locked up. The valve body went through some changes as per article but all has to match up. https://www.allpar.com/mopar/transmissions/lockup.html

Thanks for sending this, it would make sense. Would I be better off going and replacing my trans?

 

[Superbeedad]

Thanks for sending this, it would make sense. Would I be better off going and replacing my trans?[/QUOTE
It sounds like there is something internal going on and you could be playing with it for ever. Old valve bodies can act up. Has this trans been bench tested from the seller?

 

[dvw]

Post 25
The rear band can not cause 1st and reverse to be applied at the same time. It is applied in both of those gears to make them function

Post 38
If the torque converter clutch was locked it would stall the engine when put into gear. Acts just like a manual transmission clutch.

I also doubt that there is a valve body issue.
What cam, compression, intake, and carb is being used in this engine? And as I asked before. Where is the timing set? Intial and total.
Doug

 

[Dipstick]

Lots of heavy C-barges came with 2.76 gears and tight converters and they don't exhibit the symptoms the OP has.

 

[Superbeedad]

Doug is correct about the lockup clutch unless it is dragging. Another culprit is the overrunning clutch failed, jammed, or not sure on this trans but these can be put in backwards resulting in a lockup of the tail shaft. Regarding the engine, if the torque is working you should be able to feel if the the engine has power or not, but timing checks etc are worthwhile to isolate.

 

[Mason]

Post 25
The rear band can not cause 1st and reverse to be applied at the same time. It is applied in both of those gears to make them function

Post 38
If the torque converter clutch was locked it would stall the engine when put into gear. Acts just like a manual transmission clutch.

I also doubt that there is a valve body issue.
What cam, compression, intake, and carb is being used in this engine? And as I asked before. Where is the timing set? Intial and total.
Doug

Sorry for not responding sooner I was very busy yesterday, but I dont know the compression, the heads weren't shaved but the block was bored 30 over. I did port the heads before I installed and also have a 525 lift Lunati cam + matching springs with a single plane weiand intake and a 750 cfm Quickfuel with mechanical secondaries. I dont kmow the timing on it, i would have to figure out but I know its not wrong, fires right up no popping.