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Discussion Starter #1
Hello All, newbie here. I have a 66 mustang coupe with an 8" rear end, has a 302 with mild cam and holley 600 cfm double pumper and 4 speed top loader, I am wanting some more power and quickness. I am not sure what gears are in it now but she is definately not quick. She is not a daily driver and I seldomly take it on the highway. Any suggestions for a good set of gears?
 

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I daily drove my ‘66 for many years on a mini spooled rear with 4.10’s. Great around town but the highway was ok but you won’t be cruising in the fast lane. I’ve got stock gears in there now but getting ready to do 3.55’s
 

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Discussion Starter #4
Thanks for the reply, everything I am reading about is saying the same thing 3.55's
 

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I run a 3.80 gear and think it’s a happy medium for all scenarios. I run about 3000 @ 70 MPH.
 

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What carb would you recommend?
A vacuum secondary carb in the 500-600 CFM range with annular boosters. There are several Holley, Edelbrock and Summit carbs in this category and each has it's fans and it's detractors. The smaller the CFM the quicker the carb responds to throttle changes due to the velocity of the air flow through the carb.
 

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A vacuum secondary carb in the 500-600 CFM range with annular boosters. There are several Holley, Edelbrock and Summit carbs in this category and each has it's fans and it's detractors. The smaller the CFM the quicker the carb responds to throttle changes due to the velocity of the air flow through the carb.
Vacuum secondary’s with a manual trans? I was always told vacuum secondary’s with automatic and DP with a manual trans.
 

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Vacuum secondaries work fine with a manual transmission.

I you can find a 6 cyl. Pinto or Maverick they will have 8" rear ends with 3.55 +/- gears.
 

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I was always told vacuum secondary’s with automatic and DP with a manual trans.
And I always heard that "a 750 Double Pumper is the best carb ever". Nothing could be farther from the truth. Most cars that actually need a Double Pumper of any CFM are on the race track, not the street. And the last thing a 302 with a mild cam needs is a Double Pumper because DPs have mechanical secondaries and there's no way a mild 302 can handle all of that gas.
 

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And I always heard that "a 750 Double Pumper is the best carb ever". Nothing could be farther from the truth. Most cars that actually need a Double Pumper of any CFM are on the race track, not the street. And the last thing a 302 with a mild cam needs is a Double Pumper because DPs have mechanical secondaries and there's no way a mild 302 can handle all of that gas.
Bingo. Get yourself a Holley Street Avenger or Edelbrock.
 

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I second the Edelbrock suggestion. I also have a mild 302, fooled with Holleys for several years, frequently having to tinker with them. Bought a 600(?) Edelbrock and haven't had to touch it in 8 years.
 

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Discussion Starter #16
I second the Edelbrock suggestion. I also have a mild 302, fooled with Holleys for several years, frequently having to tinker with them. Bought a 600(?) Edelbrock and haven't had to touch it in 8 years.
Thanks for all the reply’s.
 

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The engine doesn't know what kind of secondaries the carb has. Yes double pumpers are more touchy on the street but the engine is not overly carbed with 600 cfm. You have bigger fish to fry if you want to make it quicker. As originally posted gears would be the biggest bang for the buck.
 

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Discussion Starter #18
The engine doesn't know what kind of secondaries the carb has. Yes double pumpers are more touchy on the street but the engine is not overly carbed with 600 cfm. You have bigger fish to fry if you want to make it quicker. As originally posted gears would be the biggest bang for the buck.
Thanks for the reply, I agree. Talked to a rebuild shop yesterday and will be taking it in next week am going to have true lok put in just not sure on what size gears yet 3.55 maybe.
 

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Dialing in the right carb is in the noise right now, if you moderate your right foot, you can keep from dumping too much fuel if that's the problem. Play with different ways to ramp into power with your right foot. With a DP, you may have to add nuance, with other carbs you can floor and go. The other downside to a DP is it is adjustable in a ton of ways. Its taken me years to figure mine out. You can flip the ramp on the accelerator pumps to get a different rate. Worth playing with but you really need to be at the drag strip or somewhere where you can feel nuanced differences. If you get a SUmmit or EB its bolt on an go...

I run a 650 dp on a 351, probably eats a lot more fuel than anything else but hey, I didn't buy my car for the gas mileage although I get 17.

First off, we need some calibration. What do you consider fast vs slow, are you comparing your car to your brother's Hellcat? NFW.

Good running 302 with mild package shoudl be fun to drive, drop to 350s and it will awaken that car right up. If the motor is not going to change much, send the distributor out to get curved to the motor specs. Folks say it makes a big difference, mine was done before I got the car so...
 

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There seems to be a fair amount of Holley bashing for street purposes. Their Street Avenger line is as reliable and “set it and forget it” as any Edelbrock or Summit. I’ve had one on my car for 12 years based on the recommendation of a friend of mine who builds drag cars and I’ve never been disappointed. I’ve driven my car all over the Midwest. Hell, I once drove it 2 hours to the drag strip, raced all day (7 passes I think), and then drove it 2 hours home - I was the only one there who didn’t trailer their car.
 
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