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Old 09-16-2008, 02:30 PM
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what size carb?

hello, i have a...
350 bored .40 over
steel crank
forged pistons
202 heads w/screw in studs and guide plates with dual springs
streeet/strip comp h-cam with a .525 lift


what size carb should i put on?

whats a good brand?

thanks,richard

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Old 09-16-2008, 02:38 PM
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What do you plan on doing with it most of the time?
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Old 09-16-2008, 02:47 PM
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Richard, they're all good brands, you just have to spend the time to get to know how they work and be able to tune them to your specific combination. In my opinion, the Rochester Quadrajet is the finest carburetor ever designed, but you'll see guys calling them Quadrajunk and other things because they don't know how to tune them and won't spend the time to learn. Carburetors are like anything else in life. There is a learning curve.

To answer your question about CFM, let's assume your cam will make power to 6,000 rpm's and we use a volumetric efficiency figure of 90%. The formula is:
CID x RPM / 3456 x VE
357 x 6000 / 3456 x .9 = 557.8 CFM
Round up to 600 CFM
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Old 09-16-2008, 03:54 PM
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I can't say it any better than techinspector about the Qjet.

Qjets are gifts from the automotive gods when they're running right. The problem is that it can be daunting to tune for the first timer and that's why many people call them quadrajunk.

Edelbrock offers a nice carb, easy to tune, fair mileage. They look nice too. They aren't an overly accurate carb. If you were able to monitor the air/fuel ratio across several loads, rpms, and conditions, you would find that it misses the mark sometimes. Effective, inexpensive, adequate, pretty.

Holley makes excellent carbs. They can be a bit thirsty if tuned for max performance, and they tend to shine at WOT. They're great for the street. Changing jets requires removing the side-mounted bowls and draining fuel which can be a mess, but there is a reason racers prefer them. HP king, thirsty, top quality, side-mount fuel bowls can leak but rarely do.

Qjet is the most accurately metering carb ever produced; factory or aftermarket. When properly tuned they are the MPG and drivability kings. The secondary air door design makes them a flow-sensing carb and they only open as much as the engine needs. The same 750 CFM Qjet was installed on V6s all the way up to the Buick 455, and its accuracy made it an EPA approved setup for GM as late as 1989. MPG kings, flow sensing makes them suited for nearly any future application, great street carb, a little daunting for the newbie.

I've not had a lot of experience with other carbs. Many other carbs are basically built on the Holley architecture, and they have mixed reviews.

All of the above is mostly fact, but some is just qualitative opinion... just throwing my 2 cents in. If you have an engine with an Edelbrock carb and switched to the Holley, (hypothetically speaking) you would gain 3 hp and lose 2 mpg. If you switched to the Qjet you'd keep the same HP but gain 2 mpg.

In short, all of them will do fine if tuned right, and techinspector has the math just right.
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Old 09-16-2008, 04:16 PM
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In short, all of them will do fine if tuned right, and techinspector has the math just right
You might find a good used 3310 for a few bucks, and then you can say you have a 750 Holley LOL What intake manifold are you using?
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Old 09-17-2008, 09:19 PM
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Definitely not a double pumper mechanical secondary.
Stick to vacuum secondary or air valve like Edel.

Tuned is the key word.
Unfortunately that might mean that specific booster venturi are more suited to your application than others. There is more to it than changing jets and twisting screws.

AED or Barry Grant will custom make you an application specific carb that will work 99% of the time "right out of the box".
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Old 09-18-2008, 01:17 AM
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Quote:
Originally Posted by ScoTFrenzel
AED or Barry Grant will custom make you an application specific carb that will work 99% of the time "right out of the box".
Ditto... and Jet Performance will do the same thing with a Qjet. jetchip.com
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Old 09-19-2008, 07:18 AM
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Quote:
Originally Posted by rchrdcmcho
hello, i have a...
350 bored .40 over
steel crank
forged pistons
202 heads w/screw in studs and guide plates with dual springs
streeet/strip comp h-cam with a .525 lift


what size carb should i put on?

whats a good brand?

thanks,richard
If you will pm us some more detailed information on your combination we will be glad to make a recommendation for you.
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