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Easy choice , 850 double pumper

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A friend is getting ready to run his fresh 422 (4.00" stroked) 340 on the Dyno. It's got ported W2 econo heads that flow 275 at .550, 295 at .600, pump gas compression (9.60 comp or so) a single plane single 4 cast W2 intake, and a stout (550 ish) hyd. cam. He's got 3 carbs to choose from, a newer rebuilt Holley 4781-5, a freshly rebuilt (stock) 1972 340 Thermoquad, and a new Thunder Series 800 Edlebrock AVS. He plans to run all 3 on the dyno to see the HP differences between them. His planned use is for street with a little strip action. Car is a 340 4 Speed Duster with 3.91 gears. Any guesses on:

Which carb will produce the most HP?
Which carb will have the smoothest power curve?
How much HP difference will there be from one to the next with no jet changing or special tuning?
Which carb will be the most streetable (somewhat subjective I know)?

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After you decide what carb your going to use after running the three. Which my vote goes to the 850
as long as you have it jetted right. I bet your best gain will be putting a 2 inch super sucker carb spacer on it, than between carbs. Entry into the intake at the 4 corners of the spacer are important here. Transition,transition. Are they going to advance the cam 2 degerees or straight up ? Sacrifice the top end for the low end torque by advancing the cam. He's running 3.91 gears so he can take more advantage of it during his strip use. I like those 2 figures.

logan426

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Of those choices... the 850dp... even the 850 wont
produce the max HP on the dyno... it could use a 1050

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Maybe with a bigger cam and more comp. a 1050
would make the max HP. The cam isn't all that
big, just a hyd. and only 9.6 comp I think the
850DP will be plenty big, if it's not junk.

Some one go borrow him a 1050 Dom and let's
find out!

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Concerning spacers, he's concerned about hood clearance, also hoping to run a stock air cleaner but not the end of the world if he can't. The Holley came with a spacer and the intake, it seems like the natural choice to me as well (4 corner adjusters, etc. pretty nice carb) but again, he's targeting a look closer to stock so it's not at the top of the list right now, actually leaning toward the TQ for use regardless of what the dyno shows. I'm not sure on the cam setup either but top end will likely be the goal since street traction will be wishful thinking at best no matter what. I'll post the numbers when he has it done.

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Street traction was going to be an issue regardless with 3.91 gear, so he needs to look at the benefits of running it at the track and using soft compound DOT tires on the street and at the track. That's my 2 cents now I'll rub them together.

logan426

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He will be running a DOT (barely) legal street slick on a stock Rallye wheel.

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You must be talking the ones with 2 lines in the
center of the tire

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what do you think the jetting would look like if he were to use a 850dp?

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J/K...