i have a 306 with vitor jr intake, 650 speed demon carb,afr185 heads,1.6 roller rockers,comp cam XE274. i was wondering on how much horsepower and torque difference a 347 with this same setup would make. i have the option of bolting this setup on and am just wondering how much the horsepower and torque numbers would change. thanks

 

God Damn man thats a silly questions thats like comparing a 302 to a 351 with the same setups! YOu are going to gain a crap load of torque and hp prolly around 20-30 At least at the wheels at the very least

 

That's a fairly good size cam for a 302 and those heads would defiantely be more at home on a 347. I think you should be right in the area of 1rwhp/ci. If both shortblocks are the same compression (for a fair comparision), I believe you'll see closer to 50rwhp gain and 50+rwtq. You'll have a better gain than compared to a 351 shortblock because you'll be spinning a lot lighter rotating assembly.