How much vacuum for vacuum switch and TCC?

[K10-Kansas]

I set my adjustable vacuum switch to 7 and 9. Seems like a narrow window but I guess that's normal. I put a 10 second delay relay on there so it won't be cycling in and out of lockup too quickly. I've got a Blueprint 350, Holley 4 barrel carburetor, and an automatic 700r4. While cruising down the highway on any uphill portion my vacuum does drop from 15 to around 7. It seems like I'd want to stay in lockup even if the engine is working a little harder on an incline right? So I should adjust the switch to maybe 5 and 7?


If I leave it at 7 and 9 I guess I'm burning more gas and the transmission is getting warmer. But if I put it at 5 and 7 would I simply be loosing a little power because the transmission is putting a drag on the engine?

Am I thinking about all of this correctly?

[Rick Bollinger]

Following and could you post a picture of your switch. I'm not quite there yet but same direction I'm going. What you are describing sounds right to me but I too would like some input on this. B&M lock-up control, Bow Tie overdrive linkage wired through brake switch.

[K10-Kansas]

Here's my adjustable switch Rick

[Rick Bollinger]

Thanks.

[K10-Kansas]

I made a wiring diagram in case anyone needs the info. I put on a time delay relay so it wouldn't cycle in and out of lockup repeatedly. I also put a light on there so I would know when lockup is engaged. I am going to move my vacuum switch down to 5 and 7. It does seem to go out of lockup too easily when on the highway just from minor accelerations that drop the vacuum to 7. Others may not need to ground their transmission pigtail if they have a pigtail. I have an 700r4 with a pigtail and it isn't grounded internally for me so I grounded it externally. So tweak this based on your setup.