A lot or recommendations for the QF on this thread, what are the benefits of the QF over the Street Avenger?
The Quick Fuel is more adjustable/ adaptable/ tune-able with replaceable air bleeds and power valve restrictions. Overkill for most (98.5%) applications but nice to have if you need them, and you know what you’re doing.A lot or recommendations for the QF on this thread, what are the benefits of the QF over the Street Avenger?
Give me some feedback on that double pumper rule of thumb, Gypsy or anyone with know-how, because I like quick throttle response as well. My 302 came with a 1406 Edelbrock 600 with vac secondaries and e-choke, AND a C4 auto....It's personal preference, but I like a "sporty" feel from my cars. Quick throttle response at any RPM is a big part of that...
Old school rule of thumb is not to use a double pumper unless the car has a manual transmission or a very high stall converter.
And when you start discussing annular vs. downleg boosters, the size of the booster changes the actual CFM the carb will flow... all else being equal.It is interesting to look up the actual venturi diameter of these carbs. Some 650's have smaller secondaries and the same size primaries as a 600.
That was a good read, leans towards avoiding the mistake of over carbing.Since this thread won't go away...
While a vacuum secondary carb is more self regulating for the street, the double pumper shouldn't be considered a pariah. Take a look at the attached graph (along with credit for the old book I pulled off the shelf).
The trick to a double pumper is knowing how fast you can go to wide open throttle. The vacuum secondaries, when set up right, takes care of this for you. Back in the day, when we were all in high school or whatever (where many experiences and old wives tales come from), it was rare for an automatic street car to be modified with better flowing heads, or just as importantly, a looser torque converter. Today, we have heads that flow amazing numbers (for cheap), roller cams and wide torque curves even from smaller engines.
The good news is the OP has plenty of options to choose from, that will work very well with his combination of parts. An aluminum headed, roller cammed 306 with a 2400 stall converter and 3.55 gears in a Mustang can easily deal with a 650 mechanical secondary carb.
One additional benefit of a DP - while cruising down the highway, you can tell when the secondaries open with your foot on the throttle as you increase speed. Not with the VS. Of course, in this case with the GV overdrive, it won't be much of an issue...
In the end, it comes down to driving style and preference.
My 570 Street Avenger has written on the carb 65 pri and 55 sec. Supports what you are stating.It is interesting to look up the actual venturi diameter of these carbs. Some 650's have smaller secondaries and the same size primaries as a 600.
Thanks I just joined the FB VMF and found the post. Looks like the guy used a 650 DP carb. He also has a little less compression ratio than my build. I am using a Hyd Roller cam as well. I may go with a 625...right between the 600 and 650.FYI, on FB was a post from a shop that dyno’d a 302 with the same heads but with a hyd roller, .526/.533 214*/222* 110* LSA and made 390 hp at 5900 rpm.
It amazes me that some people don't read what other people post lol. I used the Holley carb calculator tool and the bottom was a 570 and the top was a 650. I posted that I tried the 570...it didn't work with a crap and I tried 3 different squirters and 2 different cams to control the squirt to try and fix the off idle..then it felt sluggish pulling to redline after the kickdown. Didn't feel like a heads, cam, headers, 10:1 CR Roller 306cid at least to me by any means. I got tired of dicking with it and went with the 650 AVS2. All as I can say is the results speak for themselves...nice electric choke start up, smooth idle with good off idle part throttle, and hits hard when the secondaries open up....it laid down some really nice burn outs. With posi leaving some nice long rubber marks..I had to lift off in 2nd gear (C4)...it was not doing that before with the 570 and the transition off idle was bad no matter how much I fiddled with it. What was interesting was the GV OD shifts when doing burn outs giving 2nd an extra upshift. . Car is running great now and is meeting my expectations for a 306cid with Stage II C4 Tranny with GV OD.It amazes me how folks think they need a 650 DP on a 302 engine... do the math 650 cfm / 302 ci = x cfm / 428 ci... that equals 921 cfm.. how many folks are running out and putting a dominator on thier 428 SCJ cars to drive on the street? Even putting an 850 DP on a 428 would be equivalent to 600 DP on a 302... the 570 Holley is more than enough for the street, properly tuned of course, which is the problem...