Welcome to the site,if you don`t want to notch the shock towers,I`d just stroke a 302.With an auto. trans. it is an easy swap and will be much friendlier on the street,won`t be any more expensive either.
Greetings from the Tampa Bay area .... I used to live close to Chicago. I have a 351W and shave shock towers. My exhaust headers are positively stupid, because the ports come out right where the upper A-arms want to be. Your air cleaner will be very close to the hood. Mine goes through it. It may be a motor mount issue in my case, too, but we notched the driver side tower so that the oil filter no longer rubbed. The weight difference between a 351 and 302 pretty much goes away as soon as you put an aluminum intake on it. Puts you only about 20 lbs heavier. Mine was all done in the mid-1990s. It is now soooooo easy to stroke a 302, and that was tougher to get then. The next time I pull the engine, if it needs more than rings and bearings, my goal is a 331. Do yourself a huge favor .... look at a 302-based stroker. There are really much better exhaust choices for them, and they really do fit these cars without real headaches. You can easily make your power goal. These cars are very light, and you don't need huge torque to get them moving. I want to explore the high rpm/5 speed zone next .... Oh yeah, as far as shaving the shock towers goes .... even with a 302, GO FOR IT! ... the shave makes working on it a breeze. Do a search here ... some guys have done really clean work moving the original towers in, making the cut look factory.
Captain Comet is right,331 is the way to go,will make just as much power at a little higher RPM as the 347,and will last a lot longer.
If it's built right a 347 will last just as long as a 331 and have more torque. Too many old wive's tales on the internet about rod-to-stroke ratio. The only important rod ratio is 8 rods to 1 crank.
Well I REALLY had my heart set on a 351 small block. But as my luck would have it, I was given a complete 302 minus oil pan, distrib, starter. Small crap. I think that was the universes way of sayin just use a damn 302!! BUT My plan is to, after it gets running and looking really nice, to save up for and fit a 460 in.
I would totally disagree with this statement. I have had identical engines built (bore, stroke, heads, cams, intakes) with long and short rods. My experience is with 351W based engines. I will guarantee that a 351 built with a 3.5" stroke and a 6.2" long rod will be a smoother, stronger engine than a 351W built with a 5.956" rod. The torque curve is flatter, the engine pulls smoother and the cylinder walls wear less. The piston is more stable, ring seal is better and wear is less. You can get too long of a rod, too, and the engine will feel lazy. We had a 351W with 6.5" rods and it required a totally different cam. You also have to remember that a longer rod requires a shorter piston for a given stroke and that has a very real effect on performance. It's not just the side loading on the cylinder wall, it also effects the piston dwell time at TDC. The 331 is actually the best combination for a 302 based block if you use a stock Ford block. The 3.25" stroke with a 5.4 rod is livable. I have seen several stock 302 blocks literally split in half from the main webs up thru the lifter valley on 347 strokers. Why do you think top dollar stroker small blocks come not only with main girdles, but lifter valley girdles? Properly built, balanced, top quality parts but the block simply won't take it. My experience is circle track based and we load a block much harder than a drag or street application will with twisting, heavy deceleration under load and repeated cycles thru RPM ranges lap after lap. I can point you to circle track engine builders that routinely replace stock 302 blocks after 12 nights if the rotating mass is still alive. It's done as a routine at freshen time. The 347 stroker problems are real if you stress the engine under true race conditions. Like I said, drag and street is different and they will live better under those conditions but not as long as a 331 will. SPark
I guess I'm lost on why anyone would stroke a 302 to 347. If you want to lighter block but more power why not turbo? Or am I missing completely the reason to stroke a 302??
If you need crank work to freshen up said 302, it is now close enough in price to put a stroker in there that it becomes a pretty attractive deal. Close to same price, mo' motor. Turbo is OK, too, but I think that is another issue, and a further investment. Also, in our case with limited underhood real estate, a 302-based motor means that you can have headers that really breathe, and it gets rid of other fitment headaches. If you have your heart set on something huge, a good option is to do a front suspension swap that eliminates the shock towers. I really question throwing a big block at one of these cars. When I had a 4.62 gear in mine, it was great on a prepped track, but traction on city streets was all but gone ... these cars are light. With a big block and milder gear, you are likely in the same range of torque and leverage that you are trying to plant.
That is exactly why my 351 Cleveland is now 393 cubes - my stock crank needed work and the costs were close enough for me to go the stroker route
Ok. You tell me your experience is with 351Ws and then you procede to tell me how a 331 is better than a 347. My experience is with 302s and 347s (I've had many 302s and two 347s). Top dollar 347s will use a Dart or equivelant block, not a girdled stock block. Main girdles and lifter valley girdles are useless for preventing split blocks, they only keep the rotating assembly from falling on the ground when the block does split. The stock block splitting problem isn't just reserved for 347s, I've seen it with 302s, 331s and 347s. 99% of the time it's with the later roller cam blocks that have very thin main webs. They move around a lot and the main caps with them. A girdle won't keep the thin webs from moving. As far as the rod-stroke ratio goes, I guess all those big block Chevys are dogs 'cause their R-S ratios are terrible. Same holds true for many factory high performance engines. The OP says he's building a daily driver, he didn't mention any form of racing. There are literally thousands of daily driven 347s around and they're holding up just fine. Now, the two 347s I had both used the shorter rods with the piston pins below the oil ring land. Not that I think that made much of a difference, it just happened to be the kit I bought. And yes, I did toast both 347s but it had nothing to do with long strokes, long rods, short pistons, or side wall loading. The first one, a '74 block, encountered a little too much nitrous and I cracked a cylinder wall. The second, a roller block, developed an oiling problem and spun the #4 & #8 rod bearings. The rods then broke and peeked out each side of the oil pan. LOL (Yeah, I laugh now but at the time I was pretty pi$$ed)
The reason I mentioned most of my "hands on" is with a 351W based design is so I let you know I DO NOT build 302 based racing motors. I do have several friends in the engine building business that do, and every one mentions the same weaknesses of the 347, you've included your observations on the same issues (or non-issues as you see them). I have built several 302 street engines for projects I've built thru the years but I don't go far from a good blueprinted, balanced engine with some dress-up items on these engines. That's all I needed for those vehicles. My other reference to what I built is that we have messed with several rod/stroke/pin height combinations over the years. I do have a lot of hands on experience in that area and I do feel there is a real, and true, reason to look at rod/stroke/pin height relations when building an engine. We saw real world gains in both horsepower and longevity. That translates to ANY engine, no matter what the size, stroke or brand. There will always be exceptions to the rule that "work" but they could usually be better. Factory engines are often limited to using existing parts as size grows thru the years and compromises happen along the way (due to finances, budgets, inventory control, etc.). In a performance engine, we need to be fixing those compromises and optimizing the combination. That is where, and when, R/S is corrected and optimized. I have been asked to build 347 engines, been asked to run other people's 347 engines and declined every time. They are an over-hyped engine, in my eyes. As you mentioned, they need to be in a good block to be any good at all. Then you end up with a lousy rod/stroke ratio, bad pin location and they are harder to build compression with the shorter stroke. In our arena, that could all be addressed with a 351W based engine in a stock Ford block or Motorsports G351 blocks and we were willing to accept the additional size and weight for those gains in rod/stroke and pin location, not to mention additional cubes yet again. To the original poster: If it's a daily driver, build a 302. You're not racing it. If you want the sound of a meaner engine, there are cams that will do that for you. My experience shows me (your mileage may vary) that nearly every street car/daily driver doesn't need a stroker for any reason other than bragging rights. We want the sounds and looks. Build a nice 302 and enjoy your car since you have no performance goals, you're not trying to pull trailers and you don't need the extra hassles of running a "built" motor. That's my opinion, if you want to build 347's have fun and enjoy them. I never wasted a single dollar on one because they didn't hold up over the same time frame that the 351W based engines did in the environment we ran them. Room wasn't an issue for us so the wider engine was fine. You don't really have that room in a Mav. Enjoy your day, SPark
