???351w or 347????

67staaang · Dec 31, 2006

Hey guys i am having trouble deciding whether to start building up a 351w or a 347. Im not looking to do much strip racing, but i plan on going to get my times and all. It is mostly going to be driven on the street but im looking to get roughly 450hp to the wheels. what block and parts would you guys recommend to get me there? i currently have afr 185 heads that i want to use, is it possible to work around those heads to get 450 to the wheels? let me know if any more info is needed.. im a newb at this just trying to gain more info.. thanks again guys..:SNSign:

A67auto · Dec 31, 2006

I vote for the 351. You can go larger later if you feel the need.

dennis112 · Jan 1, 2007

dennis112 · Jan 1, 2007

450 hp at the rear wheels is quite a handful to drive on the street. Actually anything over 300 will be fun and much more is not really needed for a pure street car.

Although 450 rear hp can be done with either engine, I would opt for the 351w.

A properly built 347 is certainly capable of meeting your HP goals, but you really wouldn't have any margin for error. At 450hp, the 302 block would be at the end of it's strength capability and could split unless you purchase an aftermarket block. Your goals really don't support the $2k cost of such a block.

A 351w on the other hand, will easily handle your goals in strength and durability, most are good to at least 600hp. Properly built, it will also make 450hp at a much lower RPM than the 347 and have gobs of torque at lower speeds. The 351w will fit your 67' engine bay nicely without needing an expensive set of swap headers. They are a little heavier than a 347, but still not enough to warrant the aftermarket block.

The AFR 185's would be suitable for 450hp on a base 351w. Match them with a custom cam, a Victor Jr. intake, a 750dp Holley, and a 3:50 rear gear and you will have a nice street combo with good driveability. If you want more motor, you could stroke the 351w to a 408 or a 418 and make gobs of power. In that case, you would need more head to get the most out of the engine.

D.Hearne · Jan 1, 2007

Do a 351. No reason for a 347 in a 67 when there's room there for a big block to start with. A good block to start with is a 94-up F4TE casting. This is the only roller cam ready 351 block.

bnickel · Jan 1, 2007

450hp at the wheels is going to be pushing 550-600 at the crank. it's doable but won't be very friendly on the street, just keep that in mind

washMO66 · Jan 1, 2007

351W without question for all the reasons stated above.

I am struggling right now because I am trying to plan a new build for my 66 and while I want to go 351W block so I can stroke to 408 /410 I have a whole boatload of nice 302 / 347 parts.

PS - Dennis - I see you have accufab 1 3/4" headers, does anyone make a step header for a 65-66 351W? Say 1 7/8 to 2"? That is another reason I am thinking of just getting a Dart shortblock for my 347 and putting a Pro-charger on it or a big hit of Nitrous as opposed to doing the 408 / 410...

dennis112 · Jan 1, 2007

washMO66 said:
PS - Dennis - I see you have accufab 1 3/4" headers, does anyone make a step header for a 65-66 351W? Say 1 7/8 to 2"?

I don't know of any for a 65-66 351w with stock shock towers. I would say that nobody makes them because the transition from the header flange to the tube is too close to the shock tower to have a tube larger than 1 7/8". Really the 1 3/4"ers are pushing the limit due to the sudden bend required. Notch or remove those shock towers and you will open your car up to a world of possibilities.

nosub4cid66 · Jan 1, 2007

go with the 351w, everything being equal as far as type of pistons, rods, and crank, the 351w is a beefier and stronger engine. You also have the option to go even bigger like 393 or even 400+cid!!! I'm putting one in a 66 with a smaller engine bay and I think it's totaly worth it, in a 67 it will fit no problem, after all your car can have an FE big block without any problems.

67staaang · Jan 1, 2007

yea I think I'm really leaning towards a 351w. what internals would you guys recommend that would match my afr185s? I am thinkin victor jr for intake? comp cams? would I have to put in better suspension parts? thanks again guys

Max Power · Jan 1, 2007

67staaang said:
yea I think I'm really leaning towards a 351w. what internals would you guys recommend that would match my afr185s? I am thinkin victor jr for intake? comp cams? would I have to put in better suspension parts? thanks again guys

Stroker internals. Get a 408 kit and enjoy gobs of torque.

Suspension parts? Yah. Better brakes, stronger diff, better seats and lap belts, beefier trans, the list is endless. You cant push 500hp through equipment meant for half that and expect satisfactory results.

Edbert · Jan 1, 2007

The only advantages of the 289/302 engine is size/weight (not a big deal in a 67-70 on either account), and their increased ability to rev over the 351W. One thing that makes the 351W so strong is the hige mains, but they also make it not like high RPMs, so with both engines making 450hp there'll be a ~1,000 to 1,500RPM difference in where they make the power. One is better suited to the track (strip or road), one is more suited to the street.

I put a stock-stroked 351W in my 67 for those reasons, but am planning on more like 420fwhp. Also fun to think it weighs about the same as the 289 it replaced.

67Dylan · Jan 1, 2007

dennis112 said:
450 hp at the rear wheels is quite a handful to drive on the street. Actually anything over 300 will be fun and much more is not really needed for a pure street car.

Although 450 rear hp can be done with either engine, I would opt for the 351w.

A properly built 347 is certainly capable of meeting your HP goals, but you really wouldn't have any margin for error. At 450hp, the 302 block would be at the end of it's strength capability and could split unless you purchase an aftermarket block. Your goals really don't support the $2k cost of such a block.

A 351w on the other hand, will easily handle your goals in strength and durability, most are good to at least 600hp. Properly built, it will also make 450hp at a much lower RPM than the 347 and have gobs of torque at lower speeds. The 351w will fit your 67' engine bay nicely without needing an expensive set of swap headers. They are a little heavier than a 347, but still not enough to warrant the aftermarket block.

The AFR 185's would be suitable for 450hp on a base 351w. Match them with a custom cam, a Victor Jr. intake, a 750dp Holley, and a 3:50 rear gear and you will have a nice street combo with good driveability. If you want more motor, you could stroke the 351w to a 408 or a 418 and make gobs of power. In that case, you would need more head to get the most out of the engine.

That pretty much sums it up IMO

67Dylan · Jan 1, 2007

Max Power said:
Stroker internals. Get a 408 kit and enjoy gobs of torque.

Suspension parts? Yah. Better brakes, stronger diff, better seats and lap belts, beefier trans, the list is endless. You cant push 500hp through equipment meant for half that and expect satisfactory results.

Yeah, replacing broken parts is no fun either. Most of us have been there, done that. So much HP is going to cost, but is most enjoyable when complete.

68keyblr · Jan 1, 2007

+1 for 408 or 418 stroked 351 w. You will get the power you want with less radical cam and valvetrain, which means less maintenance and more reliability for the street.

???351w or 347????

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