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Author Topic: just wondering...  (Read 2271 times)

Offline Marx3

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just wondering...
« on: May 14, 2010, 08:35:13 AM »
Hi, I have Doug Roe's book on Rochester Carburetors, and in it is a flow-ratings chart...
It says that:

Qjets with 1-3/32 venturi is 750 cfm
Qjets with 1-7/32 venturi is 800 cfm

and....

Dualjet with 1-3/32 venturi is 227 cfm
Dualjet with 1-7/32 venturi is 287 cfm

but are those numbers comparable, or is the dualjet rated at 3.0 hg?

I have long been searching for the correct cfm rating for the primaries on the Qjet.               
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Offline Schurkey

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Re: just wondering...
« Reply #1 on: May 14, 2010, 10:37:14 AM »
Apparently they've rated the dual-Jet using the 4-barrel vacuum.  There's 60 CFM difference between the two, similar to the 50 cfm between the Q-Jets; and the overall flow rating seems pretty small for a 2-barrel.

I didn't know that they made a small-venturi version of the dual jet.  Every one I've seen is the larger style.
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Offline Marx3

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Re: just wondering...
« Reply #2 on: May 15, 2010, 10:55:11 AM »
Thats what stumbles me... but if you assume that the small Dualjet is rated at 3.0, that would make the Qjet about 160 Cfm om the primary side... thath would be about 20 % of the total flow... And I dont know if the primaries are that much smaller than the secondaries.
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Offline Toronado

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Re: just wondering...
« Reply #3 on: May 16, 2010, 04:26:28 PM »
I thought the 4 barrel was 250 primary
and 500 secondary?
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