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Old 10-07-2005, 01:56 PM
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Carb question revisited

Thanks for all the help on my last post, but I still have another question.

This was the last post.

I have a 283 with a tunnel ram and two holley 650's. Being as this is too much carb for the motor, I need someone to explain something to me.

If the carbs produce too much air for the size of the motor, why does the motor run rich and not lean. If you turn down the fuel it won't run at all.

I don't understand the theory about the air and fuel mixture. Hopefully someone can explain that to me.

I know the carbs are too much for the motor so I'm not looking for advice on carb size, just the theory about adjusting the air and fuel.
Lots of great replies to this, but unfortunately nothing really worked well, so here is my next question.

I'm looking at a couple of holley 390 cfm carbs. How do you think those will work on my motor (283 bored .030 over, heads ported and polished, mild cam)

Thanks for any help.


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Old 10-07-2005, 02:21 PM
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It's all cfm

I don't have a fully ported 283 ci, I have a fully ported 173ci.

This engine is fed by a single 390 cfm carb. All it really needs is 360 cfm.

So if you do the math, your engine likely only needs 1 of those 650's.

It will run rich because with 2 carbs you have so much idle and jet available for your cubic inch capacity. Is it bogging on you? Seems like a good candidate when I think about it.

If you really want a dual carb intake, I'd seriously look at 2 small 2 barrels. But if it was my engine, I'd be looking at about one 600 double pumper as the biggest carb I'd put on it. Just my .02

Good luck with it.

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Old 10-07-2005, 04:32 PM
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I would only go with a single carb. A 600 CFM Holley 4010 will work best.

You can try the 390s, but overall you will never get the performance of a single carb.
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