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Unread 05-20-2003, 04:39 PM   #1
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Join Date: May 2003
Location: Mississippi
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304 carb questions

I was wondering how much of a difference it is in gas milage between a 2bbl and a 4bbl carb on a 304. I was thinking about the performer intake with a basic 4bbl, or putting an adapter plate on it and put my 2bbl holley back on it.

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Unread 05-20-2003, 05:06 PM   #2
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1978 CJ7 
Join Date: Jan 2003
Location: Lancaster, Pa.
Posts: 1,759
dont know how much the milage will move but shouls see a diff in the power
1978 cj-7 had since 1979
401 .030 over- full floating flat top pistons
crower solid cam 292 dur .500/.510 lift
turbo 400 tranny 2500 stall
model 20 transfer case
aj delux glass body
4" lift
dana 30 frount
dana 44 rear
4.56 gears
13.461 @ 92.45 mph on 37" super swampers on 1/4 mile
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Unread 05-20-2003, 05:29 PM   #3
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I have the Edelbrock 4bbl 600cfm carb on my 304 with the performer intake and cam, fresh motor etc, it has primary and secondary bores so as long as you can keep your foot out of it, it will function as a 2 bbl(Primary)and when you stomp on it the 2 secondaries will open up as well as the 2 primary bbl.
Mine runs great, i did need to add the off road kit to it so it wouldnt flood out as much on hills.
As for mileage, i dont keep track, just fill the tank when it gets empty!
1982 cj7. Frame off. shell valley kevlar body, stainless hinges, Bestop seats and supertop, KC titanium lights, Homemade swing out tire carrier with spare front wheel bearings/hub, Built 304,DUI,Edelbrock shorty headers with dual stainless 21/2 tubes into incynerator cans 21/4 dumped out the back,Edelbrock 600cfm, performer intake and cam, Borgeson lower column, Centerforce clutch, NV-4500, Dana 300 w/custom built twin stick, Homade 1/4" steel skid plate, 2.5 soft ride w/ 1" shackle lift, 33x12.5 mtr's. Stainless fuel and brake lines, Braided hoses. more...

Last edited by Bulletproofcj7; 05-20-2003 at 05:32 PM..
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Unread 05-21-2003, 07:16 PM   #4
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Location: Cumberland, MD
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People tell me the 4bbl will give better mpg if you stay out of the secondaries. Smaller primary jets in the 4bbl. All bets are off once you open up the secondaries, though!!
'97 TJ
'75 CJ5 304cid, t18 tranny w/granny low, model 20 T Case, DANA 44 rear, 30 front, 4" suspension lift, 33" tires, in need of more work!

"The only thing necessary for the triumph of evil, is for good men to do nothing." (Edmund Burke)
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