Rochester 2gc - Chevy 400

[M Brand 505B]

Anyone have a 1970-75 Chevrolet parts book that confirms which part numbers were on the Chevy 400 2gc? Trying to confirm which CFM carbs were available. On the blue print specs it only shows a 1.25 carb which I believe is the 381 cfm.

Thanks,

[Greg Reimer 7376]

Look out for an OEM carb, then measure the ventures. Some of these are the 1.375" venturi, and the alternate carbs shown on the blueprint specs on your Tech Bulletin specify the smaller venturi,even though the car originally came with the larger one. Some replacement parts differed from the OEM.

[MAURICE BLENDHEIM]

Michael… 1970: 7040117, 7040118, 7040119, 7040120. 1971: 7041118, 7041137. 1972: 7042118, 7042838. 1973: 7043118, 7043119. 1974: 7044118. 1975: (4 barrel only). 1.25=381cfm, 1.312=423cfm, 1.375=435cfm. The are all referred to as "Large Base" starting in 1970. I hope this helps…Maurice.

[NORMAN BARNARD]

Maurice, what is the test pressure being used to arrive at those flow numbers?

[FED 387]

3.0-fed387

[V M Kauffman]

Originally Posted by NORMAN BARNARD

Maurice, what is the test pressure being used to arrive at those flow numbers?

4 bbl 3.0
2bbl. 1.5
1 bbl. 1.0
All are SAE Specs

[Run to Rund]

Under vacuum, 3" was used for 2 bbl since originally at WOT that was about the vacuum achieved; 1.5" was used for 4 bbl carbs. The conversion factor is discussed in Doug Roe's book, and for example the 1-3/16" venturi carbs would give 247 cfm on the 4 barrel scale, 1-5/16 about 299, and the 1.25" iirc around 280.