Seeking carburetor guidance, vacuum vs mechanical secondary

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Shawn Watson

Member
Joined
Mar 14, 2022
Posts
39
Reaction score
20
Location
New Mexico
First Name
Shawn
Truck Year
1983
Truck Model
K10
Engine Size
400
What intake manifold is on it?

For a decent test, warm it up and set the initial timing (vacuum advance removed and either line or port plugged) to 20*. Then attach the vacuum advance line to the manifold vacuum port on the carb and see how it responds to quick throttle input and hot restarts.

Don't put much of a load on the engine until you verify the total advance but that could give you an idea of how much timing the engine wants. It's hard to guess without knowing cam specs and compression ratio.

You can go old-school and creep up on the initial timing until the engine drags the starter a hair on a hot restart and go back a degree. It actually works pretty well; you just have to limit the top end of the curve once you find out the minimum the engine wants.


Shawn
 

Forum statistics

Threads
41,850
Posts
903,456
Members
33,362
Latest member
Dhatch84
Top