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#1 |
Foolish Mortal
Join Date: Mar 2007
Location: Livermore, CA
Posts: 243
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Replacing 2 barrel w/4 barrel question
Ok, so I'm at Oreilly's auto the other day picking up a brake drum, and I happen to mention to another customer who was admiring my truck (I call them "fan of the day" cause I get at least 1 comment a day
![]() ...Now I'm not a mechanic, I only play one on TV (ok, I don't even play one on TV), but that seemed a little far fetched to me. Could some of the more learned people let me know if what he was saying is true or am I correct in thinking he's blowing smoke out of his hind parts? |
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#2 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: Replacing 2 barrel w/4 barrel question
there is a huge catch with that comment.
He is assuming you can keep your foot feather light and not open the secondarys. Assuming you can do that, he is 100% right. |
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#3 |
Fat Fendered Fleetside
Join Date: Nov 2004
Location: WPB, S. FL, USA, Earth
Posts: 718
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Re: Replacing 2 barrel w/4 barrel question
vacuum secondaries are the best thing since sliced bread...
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71 GMC lwb 56 Big window swb 93 GMC Sonoma (dd) radiused fiberglass fender project for 67-72 |
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#4 |
Registered User
Join Date: Oct 2005
Location: Overland Park, Ks.
Posts: 5,216
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Re: Replacing 2 barrel w/4 barrel question
It only applies if you use a spead bore type carb like a Quadrajet. They have very small primary bores. You get good fuel mixture. But like the guys say when you put your foot in it you open the secondarys & they are huge.
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#5 |
Senior Member
![]() Join Date: Dec 2006
Location: Studio City, Calif.
Posts: 2,865
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Re: Replacing 2 barrel w/4 barrel question
The theories above sound correct,however I have noticed in 2 different 1969 trucks both with 350 engines and 4 brl carbs that if I keep my foot completely out of it for an entire tank of gas I get 11-12 MPH. Then for the next tank I'll have multiple massive loads of dirt and rock all the way up into the hills of Pasadena. Mileage; 11-12 MPG. The next tank I'll say screw it,I'm going to have fun,and act like an idiot and race anybody and everybody that wants to mess with me. And after all of this I notice that my mileage is roughly....................11-12 MPH. Always.
I've talked to other guys at the dump with similar trucks and similar stories. So I don't know what mileage you're getting now,but you might as well have the 4 barrel. You only live once they say.
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'69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, 2nd owner, Work-Truck supreme. Best $300 I ever spent. |
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#6 |
Fat Fendered Fleetside
Join Date: Nov 2004
Location: WPB, S. FL, USA, Earth
Posts: 718
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Re: Replacing 2 barrel w/4 barrel question
that's a great point , because I have a holley 2-barrel and I get from 12-15mpg, pretty much all the time. Just like you, foot deep in the gas, or barely idling along, I get the same 12-15 mpg.
Every once in a while I take it for longer rides, with no stoplights, and on those type runs, keeping it at about 45 I get some 18-20 mpg. But that's at a steady slow cruise, no stop and go....
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71 GMC lwb 56 Big window swb 93 GMC Sonoma (dd) radiused fiberglass fender project for 67-72 |
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#7 | |
Foolish Mortal
Join Date: Mar 2007
Location: Livermore, CA
Posts: 243
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Re: Replacing 2 barrel w/4 barrel question
Quote:
Thanks for enlightening me guys. Last edited by elektrik; 04-21-2008 at 04:25 PM. Reason: forgot the 1 =] |
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#8 | |
Senior Member
![]() Join Date: Dec 2006
Location: Studio City, Calif.
Posts: 2,865
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Re: Replacing 2 barrel w/4 barrel question
Mordachai says;
Quote:
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__________________
'69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, 2nd owner, Work-Truck supreme. Best $300 I ever spent. |
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#9 |
Registered User
Join Date: Oct 2005
Location: Overland Park, Ks.
Posts: 5,216
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Re: Replacing 2 barrel w/4 barrel question
Leaving it alone is a very wise decision. with All the hassle & expense of changing it over it would take years to make it up with a tiny increase in mileage.
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#10 |
Jamie Hyneman is my twin
![]() Join Date: Nov 2005
Location: La Junta, Colorado
Posts: 705
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Re: Replacing 2 barrel w/4 barrel question
It's like buying a transmission to improve gas milage. The improvement will not pay for itself.
I like driving a well-tuned quadrajet - economy when I drive like a grandma, and power when I want to smoke some young buck. But I love my hassle-free two barrel with manual choke on my 67.
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Justin SOLD 1967 K10 Fleetside, 283, Front and Rear Posi SOLD Color Wiring Diagrams Now in High Resolution V8 and Cab and Cab and Chassis |
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#11 |
Foolish Mortal
Join Date: Mar 2007
Location: Livermore, CA
Posts: 243
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Re: Replacing 2 barrel w/4 barrel question
That's pretty much what I figured...and (offtopic)why the heck does your pic look so familiar??
Last edited by elektrik; 04-22-2008 at 06:04 AM. |
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#12 | |
Registered User
Join Date: May 2007
Location: Moore, Oklahoma
Posts: 2,396
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Re: Replacing 2 barrel w/4 barrel question
Quote:
its the guy from the tv show "mythbusters" ---- i haven't driven a 2 barrel vehicle in 20 years, until i picked up a 69 a week ago that still had the 307/2 barrell. I know i am easily amused, but i have to admit to being pretty stoked about the power it still has -- it will definitely move out (but its not a barn burner, and my big block truck would trounce it, but its a match for my K5 with a 350 tbi, power wise) Mine's staying a 2 barrel, -- its my excuse to drive around like a farmer on his way to town on Sunday
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Are you retired too? Nonsense! I'm in my prime |
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#13 | |
Foolish Mortal
Join Date: Mar 2007
Location: Livermore, CA
Posts: 243
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Re: Replacing 2 barrel w/4 barrel question
Quote:
![]() BTW, Barrel has 1 "L" ![]() |
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