Rochester 2gc - Chevy 400

MAURICE BLENDHEIM · 02-11-2017, 11:54 PM

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 · 02-12-2017, 12:33 AM

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

FED 387 · 02-12-2017, 01:48 AM

3.0-fed387

V M Kauffman · 02-12-2017, 11:33 AM

Quote:

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 · 02-12-2017, 11:38 AM

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.

M Brand 505B · 02-13-2017, 05:40 PM

Thanks for the help so far. The particular carb number that is listed for the 74' 400 is 7044118. If anyone has this carb laying around can you please measure the venturi size for me?

Dave Noll · 02-18-2017, 10:35 AM

This might be of interest .......

http://www.ebay.com/itm/GM-Chevy-Che...NX~WfV&vxp=mtr

02-11-2017, 11:54 PM	#1
MAURICE BLENDHEIM Senior Member Join Date: Jun 2011 Location: Langley (no igloos), British Columbia, Canada Posts: 568 Likes: 307 Liked 281 Times in 86 Posts	Re: Rochester 2gc - Chevy 400 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. Last edited by MAURICE BLENDHEIM; 02-12-2017 at 12:12 AM.

02-12-2017, 12:33 AM	#2
NORMAN BARNARD Member Join Date: Mar 2006 Location: EL PASO, TEXAS Posts: 156 Likes: 0 Liked 2 Times in 2 Posts	Re: Rochester 2gc - Chevy 400 Maurice, what is the test pressure being used to arrive at those flow numbers?

02-12-2017, 01:48 AM	#3
FED 387 VIP Member Join Date: Jun 2006 Posts: 3,416 Likes: 522 Liked 330 Times in 178 Posts	Re: Rochester 2gc - Chevy 400 3.0-fed387

02-12-2017, 11:38 AM	#5
Run to Rund Senior Member Join Date: Sep 2007 Location: Henderson, NV Posts: 583 Likes: 8 Liked 54 Times in 27 Posts	Re: Rochester 2gc - Chevy 400 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.

02-13-2017, 05:40 PM	#6
M Brand 505B Member Join Date: Jul 2007 Location: Georgia Posts: 158 Likes: 2 Liked 31 Times in 10 Posts	Re: Rochester 2gc - Chevy 400 Thanks for the help so far. The particular carb number that is listed for the 74' 400 is 7044118. If anyone has this carb laying around can you please measure the venturi size for me? __________________ Michael Brand II 505B - F/SA Last edited by M Brand 505B; 02-13-2017 at 07:01 PM. Reason: Typo

02-18-2017, 10:35 AM	#7
Dave Noll Senior Member Join Date: Nov 2007 Location: Div. 6, Eastern, WA Posts: 709 Likes: 2,660 Liked 238 Times in 111 Posts	Re: Rochester 2gc - Chevy 400 This might be of interest ....... http://www.ebay.com/itm/GM-Chevy-Che...NX~WfV&vxp=mtr __________________ Dave Noll, EF/S ,?/SA 6526