Thread: cam advice for sbc

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First off, describe the piston crown configuration. Perfectly flat with valve reliefs or recessed crown with a narrow raised ring around the perimeter of the crown with valve reliefs or what?

Secondly, what is the piston deck height of your motor? That would be the distance from the piston crown to the deck surface of the block with the piston at top dead center. You can measure it with simple tools. Turn the crank so that #1 piston looks to be at TDC. Stand a steel rule on edge across the bore at the 3:00 O'clock or 9:00 O'Clock position as you're standing at the side of the motor. Just stand it up maybe 1/8th of an inch from the edge of the bore and use feeler gauges to measure the gap between the bottom edge of the steel rule and the top of the piston crown. Once you've done that, move the crank just slightly clockwise and measure again. Now,move the crank the other way just past where you measured first and measure again. Sometimes your eye can deceive you and if you move the crank slightly, you'll discover that you were not exactly at top dead center on your initial measurement.

The reason to use the 3 or 9 position for measuring is that if you use the noon or 6 position, the piston can rock on the wrist pin and you'll get an erroneous reading.

What I'm trying to find out here is if you have a good foundation for beginning a build.

My first reaction to the 350 heads is no. The chambers are much larger, resulting in a miserable static compression ratio that is already on the verge of awful, from a performance standpoint. The intake runners will be larger than the 305 heads, so you would really have to buzz the 305 to get any velocity for good cylinder filling. When you buzz the motor, you have to choose a cam that operates in a higher range, then you have to raise the static compression ratio to match the characteristics of the cam and there goes the streetability of the motor.

Well thank you alots! Finally i got a start on my mission. I have the weekend off so ill tear the heads off and get the spects on every thing mentioned obove and just realize that im a beginner at this. But i appreciate the motive for the rising of a turd so ill do my best with the initial measurments. ill be keepping you advice as soon as i get the info, thanks!

Hello Nathan80,I not sure but I think you asked this on another forum,that I was at.A few a those guys were not nice people,they talked to people like they were below them.I have only been here a few times,but I can tell you these guys here are cool.I glad that you are getting some respect here.

Originally Posted by Funderburg

Hello Nathan80,I not sure but I think you asked this on another forum,that I was at.A few a those guys were not nice people,they talked to people like they were below them.I have only been here a few times,but I can tell you these guys here are cool.I glad that you are getting some respect here.

Most everyone on this forum is easy to get along with, except me when I'm on my period