but I went with 347 just because it sounded cooler I would imagine both are just as reliable and durable as the other if theyre built the same more or less. but I would think the 331 would last longer since its not such a radical motor? all depends on how hard you run it and how well it was built I would say. if you cut corners in the build on either motor youll be sorry so I think as long as you build either one with quality parts theyll both last a good while for driving I would say racing the 347 is going to give more performance but as far as how long it lasts I have no clue I havent finished mine yet.
Save the money and spend it on some good heads and cam combo and spin the 302. Been there, done that, wont do a stroker again. Also a stroker without good heads is pointless also.
Age old debate, I figured it cost the same to build either one so I chose the 347, costs the same to build either. There are lots of 347s out there that are daily drivers that have lots of miles on them. If you are really concerned about it lasting then go with the 331 and put you mind at ease, you wont be disappointed with it
This is very true, to do a stroker right you can get pretty deep into you wallet. A nicely built 306 can get you good bang for your buck
Actually it costs very little more (if any) to build a stroker today vs a 302. You can do the short block for about $1500. You can easily spend that on rebuilding the shortblock of a 302, depending on what you keep and what you replace. On the other hand you can also do it on the cheap and not spend $500 on a 302, then put the money saved in heads and induction. I did a 331 simply because everyone else was doing 347's. It's been together 9 years now in two vehicles.
I've always heard 331's lasted longer cause they have a better rod ratio and put less stress on the cylinder walls or something like that. But assuming you won't be driving it every day you'd probably be ok either way.
While that's true to a very small degree.. it's not even so much the rod ratio as it is the pin placement/ring package from squashing all that extra stroke and rod length into such a short deck package. This is why some builders(especially N2O and squeezed applications) prefer using the slightly shorter 5.315 rods instead of the 5.4 inchers as it helps avoid ring encroachment issues and allows more piston meat where it counts(thicker crown/top land). It's also well known that lower rod ratios combined with larger strokes require better heads since the "pull" is stronger and taxes them much more quickly during the beginning of the induction cycle. Personally speaking.. I like to spin my motors more than most folks are comfortable with so I would prefer the 331 over the 347 in most situations except for an all out torque production in a heavy car/truck. Course.. at that point it's far better to just move to a taller 351 rather than trying to squeeze more out of these little motors. I'm seriously debating on building a long rod 289 setup(destroked 302 crank with a small journal Chevy 5.7 rod).. or 302 with Chevy 5.565 rods to run around 8,000 rpm on the street. With really short gears and 5 or 6 speed.. it sure wouldn't be slow. I've seen a few others through the years(on the street and track) and those little motors are much easier on parts while still pushing 450-500 horse due to making up for their smaller displacement with sheer rpm related airflow. You can get by with a lot less head too. A bigger motor will obviously make more power at a lower rpm.. but try spinning up a 347 well past 7,000 rpm and see what the price tag end's up at.
I have always had Fe engines (390, 427 and 428).I never messed with but 2 302 s so I am weighing in on what to put in my 72 Thank you all for your input.I too have a habbit of reving my engines pretty hard.I hadve a set of GT40 heads a guy had a lot of work done on, so the bottom is what I am thinking on.I hope to get it together and in my car by August. I still have 31 Mavs and Comets but I am cleaning up.
If you're just going to use gt40 heads then it is probably not worth doing a stroker unless you are planning on getting different heads later.
Having built and owned both a 390 and a 427 (stroked to a 454) I can tell you one thing: build a heathy headed 331 like what I did and you may never go back to the FE's. Especially in these lightweight cars. First thing I did to my Comet was trim the shock towers, after having experienced both the 390 and the 427 in a 67 Stang and all the clearance issues they had with the towers. Next thing I did was go with the 3x2 setup on the 331. Had both a 3x2 (on the 390) and a LR 2x4 (on the 427/454)
I've been running Trick Flow Twisted Wedges since late '99, they'll be going on the 331 short block I'm assembling now... Why did I choose the 331??? I guess it was because of all the hoopla over the oil rings intersecting the wrist pin bore... Was approx four years ago when I bought the stroker kit... There's a race shop in TN that selling the Pro Comps on ebay for $680 to your door, that's complete ready to bolt on, just need studs, rockers and push rods... Claim to have had zero failure with the valve/spring/retainer package they use...
The Canfields on mine are the equal to AFR165's with the 1.94/1.6 valves. I've never regretted not going bigger on the heads. With these heads, the Z303 cam (with 1.7 rockers) and the 3x2 setup, the power band starts at 1500 and pulls to 6500.
Pretty much anything other than stock iron. But the general rule is.. the more you want to cam it/spin it? The "better flowing" they need to be to move the power peak up. Which for an "as-cast/stock port location" head.. usually means slightly "larger ports" at the small sacrifice of some low-end range. But it's not like you won't want to add more gear to make up for slight loss down low and help capitalize on the extra rev range anyways, right? Otherwise.. when it comes to wider powerbands(more average power under the curve).. you may need to spend the extra cash on a CNC version of a smaller port to have your cake and eat it too. Not to say that the smaller heads those guys just mentioned above are not decent enough.. just that the mfgrs rate them by CID and RPM range for a reason, is all. The disclaimer I'll add to avoid potential arguments is that the 160 to 170cc heads just peak earlier unless you get out the grinder, is my point here. For a 331.. a REALLY good "average power" as-cast/stock port location head would probably need to be in the 180-200cc range to get really nice "fast daily driver" results. Whereas a bit more cam duration(rpm) would need larger ports/compression to be as good.. or a more efficient CNC'd version of a smaller 180/200 head would give you plenty of cake again.
