Diputado

Folks...have seen all kinds of buzz on these sites from folks who build 347 strokers out of 302s. I just don't get it...why go to all that trouble and expense, when you could just build a hot 351W instead? I know the 351 block is an inch or so taller and wider, but other than having a physically smaller (and only slightly!) engine, I just don't understand what the advantage is to making a 347 out of a 302....???

LCC

It's bigger and 100+ lbs heavier.
You can build lots of HP with a 347. What do you plan on doing, over 600HP? 302 can be had for cheap, all complete with the intake down to the oil pan. Most of the newer 351W came out of trucks. Different intakes and I believe the firing order is also different, so the cam is different. You can have a 302 already setup for a car or a 351W setup for hauling lumber??

Now if you just have a block and have to buy all the components, then yes, 351W. It can hold more power on forced fed applications. Carbed applications I don't know but would imagine what you gain in HP from the extra cubes, you lose from the weight. Someone can correct me if they please..

120mm

I would think that 347s are an affordable choice for performance, just looking at the cost of things.

If you're going to accept the weight and size of the 351W, you may as well spend some coin and stroke it to 393 or 408 while you're at it.

I imagine a 351W in stock form, or mild performance would have more longevity than a 347 stroker.

69mach1377

Compare rod to stroke ratios for an idea of longevity and then compare fastener sizes for an idea of strength...

69thunder

What does it matter? Why build a 408w stroker instead of dropping in a 390? Why buy a 65 instead of a 69? Personal preference has a lot to do with it, rarity, and some like me like to be just a little different. Arguments can go either way.

ajzride

If you have a 289/302 and you already have goodies for it, it makes sense to build a 347. But if you are going to be buying a new intake, heads, carb/EFI, cam etc for your build, then 351 makes perfect sense. A block can be had for under $200 and stroker kits are the same price. A 351 with aluminum heads and intake is only about 50lbs heavier than a similar equipped 347. For almost every argument you can make for a 347, you can make for a 408. The only real argument that stands up is that 347 do spin up faster than 408, on the other hand the torque curve from a 408 (starting about 1500 RPM) will make a 347 cry for it's momma.

69mach1377

Stroker kits are not the same price. In general, 408s cost more than 393s than 351s.
You can get a cast 393 scat crank for $300, rework some stock 351 rods and buy some 302 HE pistons for less than just about any 408 kit out there. I just went thru this exercise, but have forged pistons after all.

69mach1377

ooppss

67mustang302

302 block is lighter and smaller, important all around but especially for handling. 347 vs 351 built the same, the 347 will make a bit more power since the internals are lighter.

A lot of people build 347's because they already have 302 parts, headers, intakes, heads etc etc. If you're starting from scratch a 351 or 302 block depends on the usage, but either would work fine. The 351 block will make more power for less money than a 347, but money aside for the same displacement, 347's run a bit better. Larger 393/408/427 setups cost more than similar 347's, but make a fair bit more power too.

As far as longevity, with modern parts they both live just as long.

It really just depends on what you have laying around, what you have to spend, and what the goals are.

120mm

The only advantage a 390 has over any of the aforementioned options would be nostalgia.

Heavy, expensive to work on and just barely fits into the 1967-68 engine bay.

What's amazing is that a 351 and even a hot 347 will get it done and be lighter and probably cheaper. My cousin had a GT 390 back in the day, which I drove quite a bit, and I wouldn't go there if I could choose.

I'm delighted one can make a 302 into a 347 or a 351 into a 408. That just sounds like fun.