What carb for 400 block stroked to 451

[MEK-Dangerfield]

Ken, I visisted the links and see what you are recommending, but please bear with my basic questions
If I go your way, certainly I will have better fuel efficiency, but not necessarily economy, unless one puts fairly small sized jets on all four barrels, right?
If I am correct in this statement, then when you need the full power, you may not get it becuase of the small jets.
If, however my statement is wrong, and you put bigger jets on all four barrels, then you are sacrificing economy for power.
Pls shed some more light here to help me decide which way to go.
Thanks

Farouk,

  You can not put in smaller jets hoping for better fuel economy. If you go too small, the engine will be running lean... the car will run badly, and you will end up getting worse gas mileage. You have to look at your spark plugs to get an idea if you are running too rich, or too lean.



  Mike

[Super Blue 72]

Hey, Farouk!  How are you doing!  Hope all is well! 

I don't know if this is a feasible suggestion or not but when I think of economy, I think spreadbore carb, with the smaller primaries up front and big secondaries, ie-Thermoquad.

Are there any that are 800cfm or more?

Another idea on the spreadbore: Rochester Quadrajet carb  . 

Don't laugh that hard, I actually had one on a 318 I used a Weiand dual plane manifold that was set up for square and spreadbore carbs and I found I liked it better than the Holley carb as the primaries were smaller and didn't dump as much fuel because I still had a stock cam.

Just a thought... 

[moper]

 

MEK is dead on. You SIZE the carb for economy, or max power, or something in the middle. Then, you tune the carb you chose to work perfectly on your engine, in your location. The 750 would be fine. I dont think you nede the jet plates, adjustability is nice, but not necessary, and in your case may be a little more of a source of cunfusion and possible problem then a help.

[Chryco Psycho]

Decreasing Jet size will never increase mileage you need to mix fuel & air precisly to get the most power from the fuel resulting in the best mileage , often increasing jet size will increase economy

[Challenger_7]

Thank you all for chipping in and adding your own bit of experience. It always helps to shed more light on the subject.
OK, just to put the discussion back on track, I am not looking for economy all around, but rather find a carb that will give me all the power I need when called for, and with the most economical daily running.
My choice is still, and as HemiKen noted, a carb with a reasonable difference in delivery between primaries and secondaries, if I can find one.
Also concluding from all the recommendations the size seems to be around 800 cfm (+/-), seeing my engine has been stroked to 451, but with a mild cam, (.480 lift with a duration of 236 degrees @.050 lift).
CP recommends 800 to 850, 73EStroker uses 950 Proform, but his engine may need that being more aggressively built, and Moper says the 770 Str Avenger delivers to the equivalent of 820and his engine seems to be equal to mine. So I think this is probably the closest to what I need.
I will visit Holley's website again and do a research there, and try to keep it basic and simple.
By the way73EStroker, fuel here is more expensive than in Bahrein, it is $1.00 per liter. How are we compared to your end?
Another reason to think in terms of economy is that I drive my muscle cars a lot, and currently on either of my other 2 challengers (R/T and 400), believe me the minute I step on the gas I see the fuel gauge needle begin to move  Wrong hobby
Super blue 72, good to hear from you too;-)
Cheers

[Chryco Psycho]

I feel the 850-950 Proform is ideal , we are paying 1.25 / lt here

[dwbiggs]

I run a 750 VS w/choke (80508) and have never touched the jets and my combo seems to run fine...very responsive, no hesitations or flat spots.  I did put in a light spring though.  Is it too small...maybe....but it runs so good I am afraid to fool with anything else.