Lockup Torque Converter Causing Problems

[CdnCutlass]

I was on the highway today a noticed a vibration especially once the RPM's climbed to 2500 or beyond in OD. I suspected it may be the lockup torque converter so I stopped and unplugged the wire harness for the lockup. My car was originally a carbed 305 (non CCC) and the lockup function on the converter is controlled by a vacuum switch with two wires going to it.

After unplugging the harness and getting back on the highway I have no more issues with vibration in third or fourth gear. I guess the 400 small block thats in the car now does not have enough vacuum to properly operate the switch and it cycles the converter in and out. Should I try to get the vacuum switch to work by installing a vacuum canister or go to a different method of controlling lockup?

 

[DRIVEN]

If it's a new problem I wouldn't expect a vacuum canister would fix it. Maybe you have a vacuum leak or a failing vacuum switch. You could try a test light at the switch to verify what's happening. If it flashes while it vibrates on your test drive you'll know how to proceed.

If the problem has always been there then maybe you have too much cam and a canister might help. I wouldn't think it'd be a problem at cruise though. Usually big cams and low vacuum is more of an issue at idle.

 

[pontiacgp]

I have the TCI wiring for the lock up. I have the 2 wire solenoid and pressure switch with the wiring The vacuum switch is missing cause I just used a toggle switch to lock it up and release it. If you want it let me know and once you have it installed and it works you can thro me a few bucks. Not sure where you are, I'm in Kitchener, Ont. I have a 5 speed stick so my lock up is done with my left foot now..

 

[CdnCutlass]

The problem is more recent. It's something I have noticed getting worse. The only thing that's changed on the car is a buddy and I tried to dial in the tuning, it got more timing and some carb changes but it should actually have better vacuum as a result.

 

[CdnCutlass]

New vacuum switches are all discontinued through the dealers.

 

[DRIVEN]

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