Just looking for opinions, im rebuilding a roller block 351 for my 1993 F350 cab chassis truck. Its a tow truck so im looking for good low end. I also dont wanna get into a maf swap, plan on keeping it speed density.

I was planning on just freshing the block, boring it .040 over and decking the block to .010 in the hole. The rest of the bottom end would be basically just a stock rebuild, fresh hyper 9.20:1 pistons/bearings/rings/etc, stock F4TE roller truck cam. The top end would consist of a set of GT40 heads cleaned up/valve job with 1.94in/1.50ex valves, 1.7 pedistal rollers. Again I plan on keeping it speed density so im restricted to the stocker 19lb injectors.

My question is, how restrictive is the 351 truck manifold? I know my 302 truck manifolds flow pretty well being a rectangle port. But the 351's are oval and seem smaller? Anyone else have any opinions on how to better the rebuild?

 

The stock intake will be the choke point on your motor no question, I have heard of people porting the 5.8 lower to match the 5.0 upper but I'm not confident that is worth the effort as it does nothing to address the sharp bends in those ports. If you got a few bucks to spend the Typhoon 5.8 upper/lower combo with a 70mm single TB will fix all that, if not open up the port exits where they meet the heads at the very least, the motor will run into a wall at 4000rpm but that may be fine for your purposes.

 

I figured as much after looking at the port size, wasnt sure how an aftermarket intake manifold kit with single throtle body would behave on a SD setup. I am going for more of a "stock" rebuild but would like to get close to 270-280HP with peak torque around 3-3500rpm.