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#1
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Carb for mild 400
I built a mild 400 for my street car last year. I am running a performer rpm intake. Right now I am running a 750 holley vacuum secondary. Performance is not a primary concern. I would like to get decent fuel milage out of it. I plan on taking some long road trips (+500 miles) with it.
I have a 76 quadrajet and a 600 holley laying around. Do you think I am giving up some milage with the 750? or change carbs? I have to add the 2004r trans is great with the 3.73 gears. |
#2
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Quadrajet would be my pick. Be aware 76 model quad has the single rod APT style and is not very friendly to any performance apps.
I would look for a later model BOP unit that came from something with the 200r4 to reduce head aches with the TV cable set up. Even the 301 units are 800 CFM and quite a few had 200r4's in original application. |
#3
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Run the q jet. Properly set up, of course.
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#4
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Quote:
I believe the `75 is the oddball. `76 and `77 carbs are some of the best ones. |
The Following User Says Thank You to PunchT37 For This Useful Post: | ||
#5
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Might be good to post carb number to be safe. Or take op of carb, and show picture...
I bought one of those goofball carbs (salvage yard), It looked like the later units, until I got it home and cleaned it up and took apart...........
__________________
1977 Black Trans Am 180 HP Auto, essentially base model T/A. I'm the original owner, purchased May 7, 1977. Shut it off Shut it off Buddy, I just shut your Prius down... |
#6
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Might be good to post carb number to be safe. Or take op of carb, and show picture...
I bought one of those goofball carbs (salvage yard), It looked like the later units, until I got it home and cleaned it up and took apart...........
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1977 Black Trans Am 180 HP Auto, essentially base model T/A. I'm the original owner, purchased May 7, 1977. Shut it off Shut it off Buddy, I just shut your Prius down... |
#7
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Although I usually run Holley carbs, a well setup up Quadrajet will do much better on mpg.
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My money talks to me-it usually says goodbye! |
#8
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I would also put the factory intake on it. For a mild 400 the RPM is not a good match.
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Tim Corcoran |
#9
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Quote:
Do up the 76' Qjet, smaller primaries will give you better gas mileage and it's 75' only that has 3rd metering rod deal so your good to go! Jeff
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Carburetor building & modification services Servicing the Pontiac community over 25 years |
The Following User Says Thank You to shaker455 For This Useful Post: | ||
#10
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If your looking at putting a cap of 5500 rpm on this 400 then your average power band will be better served with a iron intake and fortunately leaves you with the Q-jet as the way to go.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
#11
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Any 1976 M4MC/ME is good except 1976 Olds still using the auxilary power piston.
FWIW |
#12
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LOL, the "goofy" carb I bought was from a 76 Olds...now I know better.
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1977 Black Trans Am 180 HP Auto, essentially base model T/A. I'm the original owner, purchased May 7, 1977. Shut it off Shut it off Buddy, I just shut your Prius down... |
#13
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I knew there was an odd duck there.
Must be because my driver is an Olds. |
#14
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How is your 750 Holley? If it works well leave it.
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466 Mike Voycey shortblock, 310cfm SD KRE heads, SD "OF 2.0 cam", torker 2 373 gears 3200 Continental Convertor best et 10.679/127.5/1.533 60ft 308 gears best et 10.76/125.64/1.5471 |
The Following User Says Thank You to ta man For This Useful Post: | ||
#15
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I had a 750-3310 Holley on the Performer on the mild 400 in the 81 TA. Bad mileage. Threw on a '73 750 cfm Q jet better mileage and same performance.
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#16
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You didn't say what car or I missed it but a 750cfm AFB would be good also. The AFB isn't as tunable as the Holley or Quadrajet but is less complex than either of them and more reliable IMO. GM went to the quadrajet from the AFB because of government emissions requirements which the AFB wasn't engineered to cope with. If you switch to the AFB use an old early to mid 60s original and not the Edelbrock copy. A '65-'67 cast iron factory intake will bolt up to '65> heads.
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#17
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17057274 I s the carb you want!
This is the Carb Cliff R ran on his Ventura. 1977 GP 400 cid. Not a rebult (replacement) carb, try to find orginal piece. Get a rebuld kit from cliff and be Happy! |
#18
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Speaking of Cliff. If you dont already have the 'Quad bible' of Cliffs, pic a copy up and learn all you can.
Cliffshighperformance.com gets the book and the best parts and tech help with the set up of Quadrajet carbs. |
#19
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The quadrajet is from a 77 Pontiac If I read the numbers right. I know the rpm is the wrong intake but I used a lot of parts I had laying around. I have the Holley tuned pretty good and runs great. I can tune Holley very well but never tried to tune a quadrajet. Mabey I should do some milage runs before I do anything.
The car use to run 11.7's with the 455 at 3900lbs. But decided to make it basically a stock cruiser. It's a 72 Lemans. |
The Following User Says Thank You to Mike S For This Useful Post: | ||
#20
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You can certainly start off with the RPM and Holley you have on hand,and see how well it works for you..
if you have enough snap to burn well into second gear then I guess it boils down to what might be the want for better fuel mileage.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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