Where did you guys get the blocks? I have seen them on Jegs for 8g's. I'm wondering if it is better to build them or go with a crate motor. I'm not too familiar with the 347, it's a stroker right? Does this mean you can start with a 302 ci block, get it bored and use a different crank/rod/piston setup? Just curious...I finished my first build and want another project. Figured I want to get the motor built and why do the same one...upgrade me!
Yep, it's just a 302 block that is bored over .030" and has a stroker crank in it. Still fits like stock and you get the stouter internals when you buy the stroker kit...i.e.-better rods and pistons.
Thats another point of discussion, I wanted to build a 347 and my machinist said he wouldn't do it for a street engine, but he would build me a 331. I trust him with what he says, he's been at it along time.
Interesting article a few months ago in "one of" the car mags. They chose the 331 for the above reason, longevity an streetability.
I have heard that because the stroke on the 347 is so long that it brings the bottom oil ring down too close to the bottom of the cylinder and this causes premature wear and the 347 engines will start sucking oil a lot quicker than the 331 stroker. How true it is ???? I don't know for sure but it certainly makes sense in my twisted head
There's about a billion of them out on the street...yeah, I counted! LOL But it's pretty common with the fox body crowd. I will admit that there was a time when the 347 wasn't as reliable, but parts and technology have come a ways since then. They were also reputed to use more oil because of the oil ring placement, which might be a detriment to street driving...but then I've seen cars that use a lot more oil and shouldn't even be driven. All things being equal though...there is no substitute for cubic inches. I mean if you're really serious about going fast, consider a stroked 351 (408 or 427). Of course then you get into header problems and plug changing problems. But you can do a search on here and hear all about those arguments.
quote from a guy i know at JE Pistions i asked him the same question before. "Regarding the piston for the 347 combination...we have found the solution in the skirt design. Many companies with less experience and racing knowledge (such as Probe, DSS, etc.) had problems with oil control due to the skirt design. Our Ford Specialist, Randy Gillis, has been running a 347 configuration in his daily driver for a long time with no issues. Let me know if you need any more information." long story short first time 347 had that issue. most likely other companies have followed what JE has done. i have JE in my motor. and have JE's in the motor i will build next... but it will be a 331... twisted wedge too lol!
Aint a dang thing wrong with a 347. If it's honed with the right stone, the right rings are used and clearances are set up right, it WILL last a LONG time. Any of ya'll ever been into a 600cc motorcycle engine? The pistons on those things are even shorter than, say, a 347. 3 rings and a pin...and not much else. The same goes for a 450cc race quad. Especially the Honda. It's nothing more than a ring holder with a pin through it. VERY little skirt area. It's all in the clearances. Too loose and the piston will rock back & forth, which pulls the rings off the cylinder wall as well as wear the ring face round, which over a period of time will start to use oil and have some blowby. JE has fixed the problem. So has SRP (same pistons as JE for the most part). Mahle has some super duper nice pistons and I don't think there were any issues with them. I have 2 sets right now...one is right here in front of me (shelf stock 331 flat tops that go in my 414"). I like Mahle because their kit comes WITH rings, so there's no guessing as to which rings to use. Plus, most of the time they're 1.5mm top ring, 1.5mm 2nd ring, and 3mm bottom ring. They have a LOT less drag! I mean a TON less drag compared to, say, a 5/64-5/64-3/16" ring package. That in itself can be worth 20-40 HP..... The oil consumption is a internet rumor that was started by people who used the very early Probe pistons combined with the Probe rings and a 120 grit final hone. Well hell...even a 302 with cast pistons is going to use oil with that rough of a cylinder wall! Both of my 414's are honed with 400 stones and then I go back in with another little tool I made to really slick 'em up. It was worth about .05 in the 1/8 mile and almost 1 full mph. And it uses no oil. If you want the extra cubic inches, go for it. The overall torque & power increase is worth it, as well as the fact that a 347 using short light pistons usually revs a LOT faster than a 302 with it's heavy pistons. That in itself makes for better street manners and sometiems even a little better fuel economy
It depends on the rod and rod bolts you use. Some have to, some don't. Even if it's needed it only takes about an hour with a die grinder and a stone to notch a block. It's not a big deal.
