how do i tell how many CFM my carb is

[69bronco]

hey i need to know how many CFM my carb is, i bought a lot of 351 ceveland parts a while ago from someone and now im trying to find out what they are. The Carb. is a 4-barrel Holley the the numbers on it are 1850-3 and the other carb #'s are 1850-2 thanks

[Mr 5 0]

Originally Posted by 69bronco

hey i need to know how many CFM my carb is, i bought a lot of 351 ceveland parts a while ago from someone and now im trying to find out what they are. The Carb. is a 4-barrel Holley the the numbers on it are 1850-3 and the other carb #'s are 1850-2. thanks.

Both of your carbs are manual choke, 600 CFM models (with vacuum secondaries).

Holley has a website: www.holley.com where you can research their carbs.

[69bronco]

thanks for the help^

[Mr 5 0]

Unless you are running a big-block race engine, vacuum secondaries (using engine vacuum to pull the secondary throttle plate open) are the best way to go - which is why most aftermarket 'street' carbs are equipped with them. They are more practical for the street. However, 'bigger' carbs (750, 850 CFM) intended for big-block engines and/or race applications (usually with very high-lift cams) can be bought with mechanical secondaries if you need them.

Holley sells a secondary diaphragm spring kit that allows you to adjust the secondary opening rate, if you wish. In fact, Holley sells just about every part of their carbs except the body, a la carte. Again, check the Holley website for details.