In the early 2000s, I was reading/researching 347 strokers because I was giving some thought about building one some day. Shortly thereafter, I also read/researched about the 331 and compared the pros/cons of both strokers. The pros of the 331 seemed to suggest (to me) that the 331 would be a better choice of the two for overall performance and longevity of engine life.

The following except is quoted from a guy who built a 347 for his 5.0L Mustang. In retrospect, he wishes he had built a 331 instead.

http://www.allfordmustangs.com/forums/5-0l-talk/210535-331-stroker-vs-347-a-2.html#post1850908

347 is about as far as you can punch out/stroke a 302/5.0L block. I suspect this is generally the primary (and maybe the only) consideration given in choice of stroker because of the bigger cubic inch number. 347 sounds more impressive than 331 but bigger doesn't always equal better.

My suggestion would be to thoroughly do your research of both and make a decision on what seems to give you the most for your money and which would give you the longest return on your investment, since neither stroker is especially cheap to build if you're using quality parts.

I would do it! (of course,I would!) Like already been suggested....check real close on clearances. You woul do all that any way. Check and double-check eveerything.
You only gonna use it in nice weather so its NOT an absolute daily driver. Sounds like all/most of the grinding work has already been done....you're gonna buy pistons anyway. 347 kits are cheap because so many guyz have built them.
If you use stock-ish heads you will choke down on the gas guzzleing anyway.
Being a nice-weather-car....I would cam"the crap" out of it to get that hot rod sound along with the tire burning torque from the extra cubes. You biggest worry will be what to do when you break the tires loose in THIRD gear too!!  YEE-HAWW!!  Go for it.....and give me a ride at the MSBB?? get together!!
6sally6

Piston oil control ring problems was the biggest issue with the 347, 10 or more years ago, because it intersected the wrist pin area of the piston. That problem has pretty much been resolved in subsequent years through different piston designs.

There's much opinions on strokers and 331s vs. 347s ....which is better and so forth. "Better" is a relative term that can only mean what it means to any given individual, at a particular time, and what their ultimate outcome or experience is with whatever the subject matter or particular situation may be.

As has already been talked about, oil consumption used to be a primary con of the 347 but, as stated, it's not so much a problem for the 347 any more. I'm not against 347s (since at one time I entertained the idea of building one). If you have one or are dead-set to build one, I say do what you feel best fits your needs and pocketbook.

Opinions are something that's variable from one person to another but, mathematics and geometry are subjects based on facts of absolutes. I look at it from the mathematical and physical (geometrical) aspect of these two strokers and see the undisputed (mathematical/geometrical) fact that the greater stroke of the 347 (3.4" for the 347 vs. 3.250" for the 331) has a much greater rod angle between the crank throw to the pistons wrist pin, --as compared to that of the 331.

This measurable difference places far more side loading forces on the pistons and those side loading forces are then transferred into the cylinder walls of the engine block of the 347, compared to what the 331 would experience.

There would be no way to change the physics of what is going to happen inside a 347 to get around this  ... other than to change the geometrical angle of the connecting rods to lessen the severity of that angle. The only way that can be accomplished would to build a stroker with a rod angle that's not as severe and would result in an engine with a longer expected service life.

....since the subject is strokers.... If a person is entertaining the idea of building a stroker but wants to keep it in the Ford small-block family, it would seem a more reasonable gain would be garnered from choosing a better basis to build upon. The better choice to stroking a 302/5.0L engine would be to stroke a 351W. The 351W is slightly taller than the 302/5.0L but is beefier in all critical areas and is already bigger, cubic inch-wise, to begin with before stroking it to a larger displacement.

Even with the added deck height of the 351W, it will still fit in the tighter confines of a '65/'66 Mustang (as compared to the larger engine bays of the '67-'70 Mustangs). Since the 351W will fit the earliest of Mustang models, the most bang for the buck would be had with a stroker based on it instead of a 302/5.0L based stroker.

http://www.badasscars.com/index.cfm/page/ptype=product/product_id=104/category_id=13/home_id=3/mode=prod/prd104.htm

http://www.hotrod.com/techarticles/hrdp_1204_the_363_the_hottest_ford_stroker/

Last edited by ultrastang (5/22/2014 7:53 PM)

For all the reasons indicated in the previous posts, I suggest that you compare the pros and cons of going with a 351W ... for me, this was an easy decision.

Well, I had my mind set I was just going to keep it a 302 and get this baby back on the road, especially since the pistons that I got with the deal were different than Iexpected and they work for my application on the high side of just right (resultant 11.6:1 static compression).  

But then I read the comments, which while a mixed bag generally are making me think 347...(or 331).  All comres down to how much time it will take me to get this thing on the road again.  Well, I have a long weekend to mull it over.