- May 28, 2015
- 1977 light blue
I timed my 77 L48, when doing so I noticed the vacuum line that comes from the distributor connects to a thermal switch (probably controlled by water temp) then a check valve, then to the port on the carb. Is it necessary to have a thermal switch, and a check valve? the check valve allows air to be drawn into the carb via vacuum, but won't allow air to move toward the distributor. I've seen other sbc engines of this era that don't have the check valve, but mine has one. Input would be helpful, and appreciated.