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Discussion Starter · #1 ·
Hi,
I have a 67 Firebird with a 1973 - 400ci engine with HEI added along with a slight cam when it was rebuilt and automatic transmission. I bought the car this way and don't have any other details about the motor. It has a Holley 650 double pumper with no choke hooked up. I have to stay with a Holley or Quadrajet for the Ram Air kit to work. The carb sits on an older Edelbrock Performer aluminum manifold. I don't want to lose any performance especially take off but I think the carb needs replaced or worked on. The choke isn't hooked up but the car starts pretty good anyway. It will only be driven summers to shows and trips and that seems to be a problem with Holleys, letting them sit. Any suggestions? I was told locally the Quadrajet will perform as good or better than my Holley, what do you think? I want an electric choke and if a Quad is the best one how about a part number. One company told me to go with a M4ME but they come in all different CFMs. I have heard the term Quadrajunk and wonder!!! Any advice and help would be greatly appreciated.
:confused:
 

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Either carb can be a pain in the a** if they aren't in decent shape.

I personally would go with the Q-Jet in your situation. The Holley you have is more for strip use and can be a POS on the street, especially without a choke. In addition, the Q-Jet probably has more cfm than the Holley, and can give you better mileage if you stay out of the secondaries.

You can probably find an electric choke cap in a junkyard for the Q-Jet. Try that with a Holley!
 

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That is not the Holley to have on your "mild" street motor. If you want a Holley, go with a vacuum secondary one. Personally I would go back to the Quad......is the Performer a dual pattern, able to bolt on both carbs? I am sure it is, but you better check.
 

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Carb to use

A good 750cfm Quadrajet would be the choice. Performance and dependability in 1 package. If you don't want to rebuild your's check out the one's at Summitt Racing. You do not want to use the M4ME or M4MC these came out when "Performance Motors" started to become de-tuned. 1968-1971 is the idea years to stay with the 4MV. They powered the 300 to 390 HP engines both Pontiac & Chevy was putting out. 1970 Q-jets used a 0.076 main metering jet on 300 & 350 HP engines, and Pontiac designated Q-jets on the 455 used the same carb on 375 HP engines. 1969 Q-jets used a 0.066 on the main metering jet on the 350 HP engines while the 390HP engine used a 0.071 main jet. Overall I think if you replaced the carb I would look for a replacement to the 1970 year. That's what we did on our 69 Firebird that was powered with a 455YH engine just running a Lunati Cam, ran great in all rpm ranges without hesitation.
 

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Well Holleys are square bore and Q-Jets are spread bore. He has a Holley so his manifold is for a square bore carb(unless he has one of those sucky adapters) All that considered I would stick with the Holley, unless you want to buy a new manifold.
 

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I thought the M4ME was for computer controlled engines.
 

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most performer intakes, all for SBC are both square or spreadbore... just need to use the metal plate for square bore for better seal
 

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Discussion Starter · #11 ·
RPM?

I wish I could be more helpful on info but the car is new to me. THe hold tach red lines at 5000 and I think that is about right for the 400 in 1973 as well as in 67. Any one know different? I really appreciate all the advice on carbs. Anyone have a Summit part # that they can recommend or somewhere else to buy? I really want to go with a new or new rebuilt one since I plan on keeping the car.
 

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67firebird,

If you want to stay with Holley, the Street Avenger 770 is hard to beat. It would be perfect for your 400 and "slight cam", plus it should be dead on out of the box for you, but if not, it would be easy to tune. Comes with vacuum secondaries, electric choke, all the goodies for a nice street car such as yours. And, you can get them at a great price on Ebay- Click Here

Hope this helps. Good luck with the new Bird!
 

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If your stayin within 5000 RPMS Id use a Road Demon 625 on your 400.
If your gonna rev up to 5500, Id say a 670 Holley Street Avenger.
 

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Discussion Starter · #14 ·
Can't find 4MV with electric choke

OK if I were to go with a Quadrajet I still need a year and model car to order it. The 4MV comes up either marine, later model Caddy, like mid 70's80's and no electric choke. I would really like an electric choke model and want to stay away from the deturned models. How about more suggestions? It also looks like Quadrajet has less problems than Hollley if it isn't driven all winter. Thanks
 

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Discussion Starter · #16 ·
I found a company that will put an electric choke on a 4MC which is a earlier Quadrajet that is supposed to work great on my engine. I just always liked the electric choke for simple installation.
 

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i bought a quad from a junk yard thought i could rebuild it like new.the kit didnt have **** in it .rebuilt it and ran like **** backfired everything.im not saying EVERY quad is like this.but hey through experience i find the light.

some info:quads use needes to richen mixture.has small primaries for better fuel economy and big secondaries for high poform.they say quads are a more NEWER desighn than holley.and is better for SOME things.also the shape of the bottom of the quad is better for THAT performance manilfiold.because its spreadbore.and more like the opening of the manifld.

HOLLEYS are performance machines.i think most race cars use only HOLLEY.
are generally easier to tune.you can buy jet tuners and vac sec quick changers and are simple in construction.GENERALLY
 

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I'm not for certain, but I think the Performers that are for Square bore won't take a spread bore, but the spread bore manifolds are drilled for both. At least, that's what the pictures on Summit's website seemed to show. I've got a Performer RPM Q-jet manifold, and I have a Holley bolted on it with no problem, I just used that thin little plate to seal up any gaps.
 

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I'll see if I can find the web address for a guy in Mount Vernon, Ohio by the name of Cliff Ruggles, He can set you up with a Quadrajet that will outperform any other carb you could get and will set it up specifically for your application. Nothing wrong with a Holley as I prefer the spreadbores myself on my GTO, even though I'm running Quadrajets on both my GTO and my 400 powered 85 Grand Prix and as for the Performer you can run either a straightbore Holley or a spreadbore carb without any type of adapter. Myself as far as choice of intakes I prefer the factory iron, as they have performed better than anything I have run on my GTO, which is a street/strip car, but you should be fine with the Performer. Also for best performance and economy you may want to consider getting your HEI calibrated also. This will help with cold starts and drivablity. If you decide to go with a Holley run the 3310 750 vaccum secondary unit and get the spring kit and take a vaccum reading and get a power valve to correspond with the vaccum reading, normally half of the vaccum reading. Hope this helps as I have run Pontiacs exclusivly for over the past 20 years now.
 
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