Flowing carbs

[RCJ]

We are racing in a stock spec style class. The carb is the restriction in the intake. I have started flowing them at 28 inches. Is the standard for carb flowing at a different depression? With the carb being the restriction should it be flowed at high depression? The head loses 30% of flow once the carb is bolted on.

[dondon]

factory 4Bbl's are flowed at 1 1/2 inches of mercury, and 2Bbl are flowed at 3 inched of mercury. I believe 1 1/2 inches is equal to 20.6 inches of water

[mag2555]

The above 20.6" H2o is correct for a 4 bbl, the 3" test point for a 2 bbl is twice that at inches or water.

[NormS]

It's a nit-picky kind of thing, but 1.5" HG is 20.4" water. Do your rules allow any carb spacers? That could help with pressure recovery , and that could help get a little more flow. Norm

[RCJ]

A 2 barrel is over 40?

[mag2555]

Bingo!

[bill jones]

---here's a link to some of my Holley 2barrel flowtesting---that might give you some ideas

http://www.ryanbrownracing.com/Bill_Jones_Page_27.html

[racinnut15xm]

So a 1 barrel should be flowed at 80?

[NormS]

Flowing 1 venturi at a time, and then adding the flows together, will usually give a lower total airflow, that flowing the whole carb. It depends on your flow bench fixtures, and how good the pressure recovery is when flowing one venturi, as opposed to what it is when flowing the whole carb on its appropriate fixture. You would want to flow each venturi at 40.8", more to see if they are close to equal flow, than to determine total flow. Norm