Can an auto trans cause a surge at low speed?

[71RR]

Heres my story. Have a 727 behind a 426 with an eddie 28 so that the 2 600 afb's are lined up. Has a purple cam hydrolic, alum heads, mopar performance dist. MSD ignition.
The reason I describe everything is that this is a fresh rebuild from what was a max wedge, and prior to the motor rebuild I still had the surge. It is a feeling like you are pumping the throttle on and off at low speed, but your foot isnt really moving. If there is a possibility it is the trans, what would it be? If you tranny experts say that it is near impossible for the trans to do this, then I am back to scratching my head over the motor. Oh ya, once you put peddle to her she lines out smooth and accelorates great. It is just at 15 - 35mph range. I have progressive linkage on the carbs and have tried her on just the back carbs 2 bbls until the linkage pulled all 8 bbls in. I now have it set where both carbs come in together. Has an elect fuel pump with 7-8# press. If you address this and need anymore info I will try to get it for you. Thanks for helping.

 

[bigmanjbmopar]

Torque converter.. what rpm range is yours? My stock one does it a little tiny bit, It's a stock 1100 rpm one. Go to the trans shop and ask them what would be the best fit with your set up I would guess 2500-3800

 

[69Bee]

I had this problem a long time back on a small block, and it turned out to be an issue with the vacuum advance. If I remember correctly, I had to disconnect it to correct the problem. Also make sure that if you do use the vac adv, make sure you use the ported tap on the carb, and if it makes a difference, connected to the correct carb (front or back). Any multiple carb guys here for insight...

 

[PurpleBeeper]

Heres my story. Have a 727 behind a 426 with an eddie 28 so that the 2 600 afb's are lined up. Has a purple cam hydrolic, alum heads, mopar performance dist. MSD ignition.
The reason I describe everything is that this is a fresh rebuild from what was a max wedge, and prior to the motor rebuild I still had the surge. It is a feeling like you are pumping the throttle on and off at low speed, but your foot isnt really moving. If there is a possibility it is the trans, what would it be? If you tranny experts say that it is near impossible for the trans to do this, then I am back to scratching my head over the motor. Oh ya, once you put peddle to her she lines out smooth and accelorates great. It is just at 15 - 35mph range. I have progressive linkage on the carbs and have tried her on just the back carbs 2 bbls until the linkage pulled all 8 bbls in. I now have it set where both carbs come in together. Has an elect fuel pump with 7-8# press. If you address this and need anymore info I will try to get it for you. Thanks for helping.

Wow...sounds just like my problem except I have a 4-speed. IMO... if it "feels" like extra fuel getting in then it's probably fuel. One thing to make sure of... when the car surges..... does it "surge up" or "surge down"? If it's a torque converter slipping or a vacuum leak or something it would "surge down" but if it's extra fuel sneaking in there it would "surge up". Maybe your fuel pump is forcing fuel past one/both of the needle/seats? You might try turning the regulator down (assuming electric Holley pump here) and see if the problem goes away.

 

[PDFROGMAN]

If the transmission is slipping you will get an RPM flare, Line pressure in the unit increases with throttle pressure. easily diagnosed with a pressure gauge connected to the unit. when/was the unit rebuilt? dried seals in the drums can leak with low line pressure.