What size cam should you use on a 30 over bored 350 flat top pistons and a 9.5 to1 compression?

Answer 1

that depends on what type of heads you have, what type and ratio rocker arms you have and what length pushrods you have. some heads have sufficient clearance to compensate for higher lift cams by having larger combustion chambers. Stock rocker arms are a 1.5 ratio on most small block Chevy engines. However, upgrades are available to a 1.6 ratio rocker arm or roller rockers. I have used both. Another variable in question is what length pushrods you are using. pushrods are available in many different lengths. If you have a cam that is too big, rather than buying a new expensive cam or worse, new heads, just get a pushrod lenght measurement tool, find out what you need to get the right clearance and get shorter pushrods. I'm going to go ahead and assume that you have a stock engine, with shaved heads. Here are a few more things to consider before getting a crazy cam. If you have an automatic tranny, a stock torque converter isn't going to support a high lift cam. You won't have enough vacuum to support the brake booster, much less any of the other vacuum operated things like windshield wipers, heat and a/c controls and doors, and other things like your positive crankcase ventilation valve (PCV valve) if you have one. Also, if you drive on the street at all, get caught in traffic a few times with a stock torque converter and the transmission will bite the bullet on you. Another thing, a high lift cam, if it clears the flat top piston head, will shake the mess out of the car. sitting at a red light, you might seriously consider wearing a helmet and keeping a bottle of Ibuprophen with you. If i had to recommend a cam for your application, i'd say something along the lines of a 3/4 cam. Like a 286 magnum flat tappet cam. you get a 286 duration with about a .490 lift. that will give you streetability power and responsiveness with out losing vacuum or shaking you to death on the way to work, and will not interfere with other internal engine parts. let me know if i can help anymore.