Thread: Intake Help?

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So i have a sbc 350, it is bored .60 over, has a mild cam, and 305 heads. The compression is about 11/1. It was just rebuild about 300 miles ago, and it has a single plane intake on it. Ive been told that this is the wrong intake for stock heads, and that i should put a dual plane on it. Is this true? If so what would be a good intake/carb setup for this motor?

600-650 cfm carb of choice- Edelbrock Performer or Performer RPM intake - buy used intake $50-$100

Single planes are for wide open throttle.

If you're actually driving it, a dual plane is better.

Originally Posted by 29chev

has a mild cam. The compression is about 11/1. has a single plane intake on it.

Wrong plus wrong equals wrong.
11.0:1 static compression ratio plus mild cam equals detonation on pump gas.
Single plane intake equals inferior cylinder packing and less power than a high-rise, dual-plane under the torque peak where you do most of your driving with a street motor.
Further, if you didn't know any of that, I'm pretty sure you don't know anything about the block deck height, piston deck height or squish of your motor. If the squish is excessive, you'll never get it to run on pump gas even with a cam change in my opinion.

Here's a tutorial that I wrote for another forum, after extensive research into the camshaft/compression ratio question.....
http://www.crankshaftcoalition.com/w..._compatibility

Well, I was thinking about responding to this post last night. This is a whole lot bigger than a carburetor/intake question. Tech beat me to the “punch line” but he went exactly where I would have. Maybe we can backup a bit here and help you out. I would also recommend you read this thread to understand/appreciate the wisdom on this site – especially where Tech is involved:

355 build HP and Torque?

Adopt Rollie’s mind set and you’ll find that we can give you a lot of help and get you where you want to be with your ride. So let’s start with some questions:

What is this engine in?
What is your rearend ratio?
Automatic or stick? If automatic, what is your stall speed?
Which 305 heads? Do you have the casting number(s) and why did you go with 305 heads?
What pistons are in the engine?
How did you determine that you have 11:1 compression ratio? As has been mentioned, at 11:1 you’d be hard pressed to have this engine running on pump gas.
What make and model is your camshaft?

These are the basic questions – let’s get through these and see where you’re at. You’re certainly at the right site to begin your “engine education” but it’s up to you. Know-it-alls don’t do well on this site, but those who have a desire to learn and want to take advantage of the deep knowledge the people on this site represent can come out as real winners. It’s your move

Regards,
Glenn

Thanks for all the help. This is a learning experience for me because im 17 and this is the first engine that ive actually got into.
This engine is in a 1929 chevy, which is usually just my weekend driver, and im not really sure what the rearend ratio is because i havent really got into that yet. But it came out of a 1978 camaro and it has an automatic transmission. The casting number on the heads is 376450 and it has flat top pistons. the cam is a performance .447 lift. I used these heads because they are the ones that came with the engine when i purchased it. This engine was rebuilt by a local shop, and they told me that it had about 11:1 compression with these heads, and i would have to run 91 octane in it.
Thanks again for the help!