Woodsy, 50k miles is not a good service life for a street engine. For a *****-to-the-wall weekend driver, maybe, but a lot of us like to drive our cars, and quite a few of us (me included) use them as daily drivers. If I only expected my 331 to last 50k mi, I'd be over halfway done with it, and I only built the thing about 5 years ago. But it's a long-rod 331 instead of a short-rod 347, so I expect it to last well over 100k mi, even with me beating the crap out of it.

 

My customers 75% Fox body guys, the other 25% are older mustang / AC Cobra guys and the first thing I ask them, what are your goals, aspirations and how many miles per year. 99% tell me, maybe 5k miles per year. "It's just a weekend toy / weekend warrior" For a weekend warrior / toy which 99% of these cars are, 50k is a very long time. My pizza delivery customer, daily driven fox body, one of the dreaded 5.400 rod 347's I built for him, 67k miles and ticking. With all that stroke and that horrible piston pin in the oil ring 347, it should be about done by now, puffing away eating oil. Alas it does not. There is an overwhelming amount of bad info in regards to small block fords on the internet its unreal. Same nonsense day in and day out.

 

I like my 383. It has a slightly increased stroke so you can get nice torque but still spin it to 7000 with good quality parts. I did go with a Dart Sportsman block, which is totally awesome. Once it is seasoned and I get tired for playing with 475hp/475ft*lbs, I will bore it out to 4.1+ and possibly increase the stroke. 383/393 is a good combination stroker, IMO. With a large stroke motor, you are limited by piston speed as to how high your can spin it. For a street/strip motor, I like to have both torque and some high end horsepower. As you increase stroke, you decrease the redline. Remember that when you are considering what you want to do with the motor.

 

vegas the GT40 heads will work although you'll have to drill the head bolt holes bigger for the larger 351 bolts. problem is those heads will choke a 400+ c.i. motor.

 

So why are you still building 347's unless it's a 3.25 x 4.125 combo? The 3.4 stroke w/5.4 rod and an 8.2" deck height is about the worst stroker combo in the aftermarket from a design and function standpoint.

 

I know there just horrible, I build about 75 of them per year, funny how all the mythical internet problems with this engines are based off of rumor and hearsay, especially all the internet engine builders. Let me guess the poor rod ratio?

 

50k mi out of a 347 is pessimistic. I might hazard a guess at something like 100-150k, depending on how it's abused, but in the end it will have a shorter life than a 331, and 16 cubes aren't going to make that much difference in how much power you can make. Let me know when you see a 347 last 200k mi.

 

most of the problems people have with longevity and hi performance engines is in the quality of the build. if decent (note i said decent, not the best) parts are used, it is balanced, and BUILT PROPERLY IN A CLEAN ENVIROMENT it will last a long long time unless its getting the sh*t kicked out of it at ever stop light.

 

I hear this out of the 331 guys all the time, they are always finding a way to justify building the 331. How many have you built? When you get to 150k miles on your 331 let me know, and with said thinking above, the 289 GOTTA last atleast 300k miles correct? Also howmuch shorter of a life?

 

When I get there, I'll be sure to let you know. I've known several people with 200k+ miles on their 289's and still running strong.