Team Chevelle banner
1 - 6 of 6 Posts

·
Premium Member
66 Chevelle SS396 & 66 Chevelle 327 Convertible.
Joined
·
7,512 Posts
Discussion Starter · #1 ·
This is on a 2004R rebuilt about 500 miles ago. With BowTie Overdrive EZ TV cable . Lokar shift linkage on a 66 chevelle. Lockup in 4th gear only. Power from fuse box to a brake switch to a vacuum switch and then to the transmission.
With power disconnected, trans works fine and engine runs great. The problem happens only after trans has shifted into OD on light to moderated acceleration car misses and rpm drop, then back to normal, then miss again and so on until I get over around 50 mph. Converter is locked. Also this does not happen at WOT.

Adjusting the vacuum switch up or down when lockup is suppose to happen either up or down doesn’t solve the problem. Switch is suppose to be adjustable from approx12* to 20* of vacuum. Mild cam. I was thinking of running the car with power directly to the trans. If it acts as it should then it must have something to do with vacuum switch or engine vacuum. If problem still exits I would think it has something to due with the converter or the trans rebuild. Any thoughts on this? Or has anyone else had this problem?
 

Attachments

·
Premium Member
66 Chevelle SS396 & 66 Chevelle 327 Convertible.
Joined
·
7,512 Posts
Discussion Starter · #6 ·
Thanks guys, I really don’t know much about this system. One question Von, are you saying that if trans is not locked up the trans will run hotter, so I should make sure the trans locks up? I messed with the switch a little last night. The adjustment is suppose to be from 20* to 12* according to the instructions. There are 9 full rotations . I turned in all the way, thinking that will lockup at 20*. When cruising on a level road it seems to lockup and I see the rpm drop around 200 rpm. With the slightest addition of more throttle I can feel the converter unlock and see the rpm go up. I first thought this was an carb or ignition problem. I plan to turn the adjustment back 1 turn and see how that works. Then 1 more turn and so on. If that doesn’t get me to a good feeling, the addition of a on/off switch sounds like a good idea no matter what. A friend wants to test the switch, that will likely happen this winter.
 

·
Premium Member
66 Chevelle SS396 & 66 Chevelle 327 Convertible.
Joined
·
7,512 Posts
Discussion Starter · #11 · (Edited)
Thanks again everyone. This I the cam kit I put in if that means anything. Cam K-Kit CS RF-V262HR12. With my limited experience I am not sure if I accurately explain the issue. I friend is going to test the switch to see if it is operating as it should. Unlikely but you never know. I have. To drive it a bit more to look at the rpm’s when it’s happening.

as I understand the switch, it’s suppose to allow lockup at say 18” of vacuum, then if the vacuum drops to say 14” of vacuum it will unlock. Correct? Seems like lockup happens, then about 1/2 a second later it unlocks, then happens 2-5 more times. Mostly occurring around 18000 to 2000 rpm. Again, never happens when no power to switch.
 

·
Premium Member
66 Chevelle SS396 & 66 Chevelle 327 Convertible.
Joined
·
7,512 Posts
Discussion Starter · #15 ·
Sounds like I have the same exact problem. I have a column shifter. I think a switch under the dash would work for me. And the time delay sounds interesting. Did you leave those low shift points. I have been trying to get mine to shift around 2400,:2400, and 2400. I have a 3:55 speeds would be around 18, 36, and 52 mph.

I just have a single terminal at the trans for 4th gear lock up only. So would my wiring be different.
 
1 - 6 of 6 Posts
Top