500 or 600 cfm carb?

[jasray]

I have a stock 289 in my 66.

I was wondering if I should go with a 500 or 600.

I do plan on building the motor up in the next year.

Any help would be appreciated!

Thanks.

[PKRWUD]

If you want to run a 2bbl, go with the 500. If you want to go with a 4bbl, go with the 600. Either one will be fine.

Take care,
-Chris

[MetalHead]

I have a 67 with a 289 and i when i had this decision about a year ago i went with the 600 cfm edelbrock. there was a big improvement in power and top end speed, just make sure you have an exhaust that can handle it and make sure that you set the idle mixture properly, mine ran way too rich in the beginning and bogged a lot off the line. good luck!

Jason

[Rev]

My advice is to get a 600 Holley with vacuum secondaries and then tune it as needed for max performance. Get a Holley book to learn how.

Rev

[jasray]

Hey!

Thanks for the advice on the carbs!

I will definately go with a 600.

Should I get a performer intake or a performer RPM model?

I really dont know the diff.

Thanks!


Jason

[Clark Rodgers]

The Performer is a good stock replacement intake it fits and looks like stock but saves alot of weight. It is good up to 5500 RPM where the RPM is good from 1500 to 6500. The RPM is also taller but if you are planing more performance upgrades I would go with the RPM.

Don't underestimate the previous comment on the exhaust, what comes in has to go out, so headers and a good dual exhaust are a must. Your stock 289 will have a hard time using all that fuel and will give you that all familiar black smoke when you get on it.

[MetalHead]

It sounds like you don't just want to replace all your parts with stock replacements, but are looking for a more power. In that case I would go with the Peformer RPM, it will go well with that 600 carb. The Performer intake is stock replacement and the RPM is for better performance. I went with the Performer PRM Airgap intake, its the same as the RPM intake but it uses the airgap configuration that they use on their victor series carbs. It keeps the runners from the base of the intake so the mix stays cooler. just my opinion though. good luck

Jason

[jasray]

Thanks guys!

I will definately get the rpm manifold.

Thanks again!

[thehorse]

just a lil horsepower rule: around 2.0 cfm per cubic inch of engine. so i would have to say 600 cfm and if you get the rpm manifold, you might want a little spacer between it and the carb, you'd be amazed of the difference. hope this helps and good luck

[jasray]

Thanks for the input!

Will a rpm manifold and spacer fit under a stock hood?

Jason

[Rev]

Spacers don't always help. They are cheap though ($15-20), and so are worth a try even if they don't help. Do measure the under hood clearance though to make sure you can fit it in before you buy it.

Rev

[MetalHead]

Why would you want to put a spacer between the carb and the manifold? what purpose do they serve and what are the effects? How do you know if they are good or bad for your engine?

thanks
Jason

[Clark Rodgers]

Jason,
without getting into a physics lesson, the spacers help increase the velocity or speed of the air flowing through the carb, but this is hard to judge how much effect it has, especially if it's thickness is under a inch.

The biggest help is dealing with the heat, I use the one like the boss 302 came with it is a composite type material and helps stop some of the heat transferring into the carb which helps it perform better.

[thehorse]

the spacer can be properly used mainly on dual plane manifold(performer RPM) with a mediocre flow carburetor will make the manifold function more like an open-plenum design and increasing the plenum volume under the carb will improve airflow and reduces fuel distribution irregularities. It's not that complex.