347 vs. 351

[LuckyWinner]

If all engines have 400hps, is there any difference in the way they drive? Also what about the life span of each engine?

[Mike N]

The bore is essentially the same on the 3 engines you noted so the fundamental difference is the stroke. A longer stroke will naturally give you more torque, just think of using a cheater bar to break a bolt loose. A longer stroke will also put more stress on the bottom end due to the increase is rotational inertia. So the 347 and 351 will tend to have a better torque curve than the 306 with same heads, cam and intake. Also the 306 will tend to be more peaky than the 347/351 to be able to hit 400 HP. In fact a 400 HP 306 is probably a borderline streetable engine. But hey if you are going 351 why not make it a 408? It won't cost any more and you will have power and torque to spare.

[AJ Roadster NJ]

The old saying..."There's no replacement for displacement."

I was in exactly your situation when I planned my build. My paper target was to get 400 hp. I actually bought a 302 block with the intention of building a 347 stroker. But then I sold the 302 and went with a 351W. Why did I do that?

First, a warmed-up 351W is going to suffer a lot less internal stress from rod angle than a 347, which is a stroked 302. This affects, among other things, oiling issues.

Second, achieving my 400 bhp target was relatively simple on a 351W. I am an old believer that a motor is a complete system, not just a collection of parts, but here is what I ended up with;

Stock crank and main bearing caps, cleaned and magnafluxed
ARP fasteners throughout, no exceptions (this, at times, made my credit cards beg for mercy)
America Eagle rods, weight matched within 2 grams, "stock appearing"
Keith Black hypo pistons with full floating wrist pins
Speed Pro moly rings
Dart Pro1 heads, fully assembled
Comp Cams; retrofit roller lifter spider, hydralic roller lifters, pushrods, small-base-circle retrofit hydraulic roller cam
Weiand Stealth intake manifold
Barry Grant Speed Demon 650 cfm carb, no choke, mechanical secondaries
K&N round air filter.
MSD; 6AL ignition box, distributor, Superconductor wires

I'm sure I'm leaving something out.

I built mine. It has been pointed out to me that I could've bought a crate engine a lot cheaper than doing this build. Doesn't bother me. I enjoyed assembling this motor so much, and got such a huge thrill from hearing it run the first time, it was worth every penny. And I get to say I built it, and that matters to me a lot.

Don't know whether I hit the 400 target or not because it hasn't been dyno'd yet. But I'm pretty sure I'm over, more likely in the 420 range.

Good luck!!

AJ

[Wayne Presley]

the 351W block is also much stronger than the 5.0 block, if you ever want to make 475-500 RWHP the 5.0 block will split in half right down the lifter valley where the 351W will do just fine

[CraigS]

The 351, as Wayne said, is a stronger block.Head bolts,main cap bolts,oil pump drive shaft and others are one size up from the 302.Since the 351 is a taller block,the headers need to be different than the 302 so i think the plan is to start w/ a 351 so you don't need to change later.As a reference, my Engine Factory 351/400 hp is a plain stock block,crank and rods w/ Edelbrock Performer RPM heads and intake and a real mild cam.It is super easy to drive on the street.