Let's Talk Torque Convertors

[BUCKETOBOLTS]

Here's the deal. I gathered parts to build the NP435/203 doubler. I needed to pull the tranny to have the main shaft cut and resplined. So as the back up plan I pulled the C4 from my parts rig and rebuilt it for duty in my trail rig. I let a pal of mine talk me into using a step-up from stock torque convertor(1600-1800). With the rig idling in gear with the brakes on, I can flash the convertor to about 1800-2000 on my cheap-o tach. Just as advertised. My peeve is that when I'm cruising at say 2200 rpm in high(without a detent) and mat the throttle it is flashing to 3K. My engine makes great low end torque and I believe it is blowing threw the convertor. It just feels weak to me. Maybe I should have just went with a stock one.

 

[SaddleUp]

Here's the deal. I gathered parts to build the NP435/203 doubler. I needed to pull the tranny to have the main shaft cut and resplined. So as the back up plan I pulled the C4 from my parts rig and rebuilt it for duty in my trail rig. I let a pal of mine talk me into using a step-up from stock torque convertor(1600-1800). With the rig idling in gear with the brakes on, I can flash the convertor to about 1800-2000 on my cheap-o tach. Just as advertised. My peeve is that when I'm cruising at say 2200 rpm in high(without a detent) and mat the throttle it is flashing to 3K. My engine makes great low end torque and I believe it is blowing threw the convertor. It just feels weak to me. Maybe I should have just went with a stock one.

I think you need to adjust the modulator. It sounds like your stall speed is somewhere around 1900 if what you are saying is right. A lower stall would be better for off road use but 1900 shouldn't be too bad. (Mine stalls at 1500) To check the stall speed put it in gear with the brakes on and push the throttle watching the rpms. The point where the rpms stop rising is the stall speed. Getting back to your problem if it stalls at 1900 yet jumps to 3000 when you are driving then it is due to slippage inside the tranny not the torque convertor. If the modulator is out of adjustment (I think the wrong torque convertor could change it) then it can cause this.