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Discussion Starter #41
A lot or recommendations for the QF on this thread, what are the benefits of the QF over the Street Avenger?
 

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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.
 

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As I stated earlier, Quick Fuel Brawler 650 vacuum. Great value for the money. I love mine. Also comes in race and DP. I use the race version, (no choke).
 

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...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.
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.

I'm converting it to a roller 302, T5z manual, 3.73 rear end and my 302 has 170 TFS TW heads, B303 cam and 1.7 roller rockers, and I will likely only once or twice drag it just to see, but it's going to be a tight handling road course/street car, hopefully, when I'm done. Dual plane Edelbrock manifold.

No emotional connection to the Edelbrock, almost pulled the trigger on a FiTech, Sniper, multi-port EFI but held off, figured too many changes at once, let's break it in with a carb?

Should I stick with the 1406 or is the Summit 600 with 'annular' (whatever that is?) boosters THAT much better, that I might like it so much I don't bother with EFI for a while?

Crapola! Looks like the Summit carbs are vac secondary only?!?
 

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“Crapola! Looks like the Summit carbs are vac secondary only?!?”

I’d say start with the Edelbrock first.
And if you feel it could use a little more, get a Holley 650 double pumper.
 

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Maybe I should just stick to one line responses. lol

All snark aside, I'll keep it simple. For anything except for *possibly* professional drag racing, annular boosters are really really amazing.

For street, especially on automatics with stock torque converters and highway gears, vac secondaries work best.

And lastly, 600 CFM is a really good size for any 302 under 350 horsepower or so. Maybe even 400.

You can get all those features on a Holley type carb, for about twice the price of a Summit M-series carb.
 

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Discussion Starter #47
So with my setup I'm somewhere close to what you pointed out.

306 cid 10.1 CR (Roller)
AFR 165 Heads
Lunati 218/218 Cam, 1.7 Lifter (.550 lift), 1800-6000 rpm range
Edelbrock Performer Air Gap Intake
Stage II C4 with 2400 stall, GD OD, 3.55:1 Trac Lok Diff.
1 5/8" Headers
2.5" Exhaust

It should be over 350 closer to 400 bhp.

Going to be on the street for cruising and spirited romps to 6K rpms.

The Holley calculator says 570 is at the bottom of the range, I see 650 is near the top. Found one build that used a Holley 625 street demon carb that made over 400 bhp with AFR 165, 1.7, and stock cam.
 

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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.
 

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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.
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's a mixture (pun intended) of Voodoo, Engineering and Marketing...

One example of the complexities, the List 4780 800 CFM DP has 1 3/8" primary venturis while the secondaries are 1 7/16" - not exactly square like you would assume from a Holley. It's how they cut the difference from the 4779 750 CFM and 4781 850 CFM units.

Add in the HO line, Demons, Street Avengers and Quick Fuel options, plus others like AED, Jet and Willy's, there are no shortage of options on getting a good running, well matched Holley for whatever you build. And that doesn't discount the Autolite, Summit and Edelbrock options too.
 

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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.
 

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Discussion Starter #53 (Edited)
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.
That was a good read, leans towards avoiding the mistake of over carbing.

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.
My 570 Street Avenger has written on the carb 65 pri and 55 sec. Supports what you are stating.

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.
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.
 

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Discussion Starter #54
Circling back. Tried the Holley Street Avenger 570 that I had and couldn't get it to perform as well as I thought it shouldn't. Played around with squirters and cams for off idle, and it wouldn't pull as hard through the rpm range to the top. Went with a Edelbrock AVS2 650 vacuum secondary carb. Out of the box it has great start up, off idle part throttle driving, and gets it all the way through the rpm range now. Nice looking carb too. The annular boosters are the way to go I think with an auto tranny.
 

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I ran a "tuned" Edelbrock 1405 on my rig from when it was a basic 289 with duals, Tri-Ts, and PerformerRPM intake until it was a 331 stroker making 350 RWHP. It was on the next build iteration when I went with a bigger cam and TW heads that I needed to go larger and that was only a custom 680 Holly XE. Each change provided a "crisp" throttle response. This, in my thinking, is what works well on the street. BTW, the "Holly XE" is listed for sale in my classifies. Since I moved on to ,yet, another upgrade.
 

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Forget the double pumper. Look for a carb with annular boosters such as the AVS @Shinobi68 suggested.

The reason a double pumper has 2 accelerator pumps is because when you open both sets of throttle plates, you're over carburatoring which causes the fuel circuits to stop working. The accelerator pump is a crutch to make up for it. A vacuum secondary opens only as the engine NEEDS more airflow.
 

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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...
 

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Discussion Starter #59 (Edited)
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...
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.
 
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