302f150

Spacers and plenum dividers provide an easy way to change the configuration of the intake tract and the relationship it has with the carburetor.

Adding a plenum divider to an open plenum manifold will help keep the left to right fuel distribution balanced for oval track applications when the car is in the corners. This is especially helpful on alcohol engines. These dividers usually do not have a measured affect on torque or horsepower.

Using spacers between the carburetor and intake manifold can produce dramatic results. The use of a four hole spacer can improve low end to mid-range by helping the carburetor draw and atomize fuel. An open center spacer increases the plenum area and can benefit the mid-range and upper rpm power. It is not uncommon to see combinations of spacer types or stacking of similar type spacers being used. It is also not uncommon to see results that are totally opposite from the general tendencies.

The actual results from any spacer or combination of spacers can only be measured during a test and tune session on the specific engine combination being run. This information can be a very useful tool when tuning to find the best horsepower or to change the power characteristics to suit a specific track condition.

Excerpt from -Barry Grant - Basic Carburetor And Fuel System Maintenance And Tuning-

I can't find anything giving numbers or proof about anything. But everyone seems to agree they help heat soak, but they never say how much heat soak affects performance. If anyone has an article on this, please show me, im only 19, so carbs arent exactly something im familiar with. Theoretically i agree, heat soak=bad, get a spacer. But i havent seen anything showing how much a spacer helps heat soak, and how much that in turn helps the motor. I have found several people that said a spacer decreases your throttle response.

85stang1373

well then would this increase mpg also? And what in the world is heatsoak? Im thinking it mean excess gass being soaked up and absorbed or someting right?

89gt347

uugghh![:@] Can't believe you quoted barry grant.[:'(] That's ok though, I won't hold it against you.
Anyway, carb spacers do insulate the carbfrom heat and also increase plenum volume. However, depending on your combination and the weather conditions they might not do anything for you and may even hurt power (I've seen this happen in "bad weather")
As for the "plenum dividers" these usually only hang down into the plenum only about an inch, but vary (again, according to combination and weather) and they help to increase throttle response.

golden_eye

Not sure about MPG... I know next to nothing about carbs other than how they work. Heat soak is when heat from the engine actually gets absorbed into the metal intake(since metal is a good heat conductor) to the point where it heats up the air going into the engine. This is bad because hotter air is less dense and therefore doesn't produce as much power as a colder (and denser) intake charge would be. The whole idea is to squeeze as much air into the cylinder as possible.