Heres my problem. I'm going to rebuild a engine sometime next year. MY three choice are the original 307 cu, which has been bored out .030. My other choice is a 350, right now it has lt1 heads, a huge holley 750cfm carb, which is too big. And the last choice is a 327cu. It will be going in a 1969 camaro backed with a th350 tranny. I also plan on installing diff gears in the rear, possibly 3:7:3's. It is a daily driver. Thanks Jon

 

Well, since I'm not too familiar with 307's, I can't say much about it.

If it were me, I'd definitely work with either the 327 or the 350, but personally I'd go with the 350. A 327 will be a high-revving motor and can put out lot's of HP, but the 350 will give you a lot more torque, and with more torque comes more HP. Honestly though, it's your call, and it depends on what you want the car for. If it's going to be a highway cruiser car, go with the 327 since it will like to sit at higher revs better than the 350, but for a predominantly street/strip driven car, I'd say the 350 would be the better all-round engine.

A TH350 and 3.73 gears are also a nice combination behind a 350. And with the right cam and a little tuning, there's no reason you couldn't stick with the 750 Holley you've got --- it may need smaller jets or something, but it should work ok for ya.

Hopefully this is somewhat helpful to ya. I know it may be a little vague, but at least you can maybe get some direction.

 

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Hopefully you get it all together, I would go with the 350, for standardization purposes. However, why is it that you say the 750 is way to big? I have read Hot Rod atricles disspelling the myth about "too big" carbs. They say that when it all comes down, an engine is only gonna suck in what it needs, and can never have to much, but maybe not enough.......what do you think? Makes sense to me Just wanted to see your thoughts

BamaZ28

 

don't bother with the 307 - you will have a hard time finding performance pistons for that engine.
I'd do the 350, or even stroke it to 383. Lots more power than either the 307 or 327.

As for the carb size, you can have too big. It is true that the engine will only suck in what it needs, but the carb needs a good vacuum signal from the engine to meter fuel effeciently and provide good throttle response. When you put in the larger throttle bores of a bigger carb, the vacuum signal gets dampened because the air is flowing through a larger area. That's why q-jets have such tiny primaries - better throttle response and economy.
Some of this will be controlled if the carb has vacuum secondaries, because you won't be able to totally bog the engine as easily, but a properly-sized and tuned carb should always run better than a too-big one.
Of course, you can always build up a 350 to make good use of a 750 carb - a 350 that revs to ~7000rpm would be about right.