331 vs 347..???
10-02-2013, 07:42 PM
#1
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331 vs 347..???
Hey folks, in the distant, distant future I'm considering getting a better engine for my '65, and have been looking a lot at some of the crate engine offerings (such as from Bueprint Engines). The 347 Stroker sounds like it would be a blast in a '65 coupe, and they also have a 331 Stroker. Both are similarly priced. So...other than "personal preference", are there any technical/mechanical reasons why someone would choose one over the other?
10-02-2013, 08:12 PM
#2
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347s 'used' to have compression ring in the wrist pin issues so depending on the kit pay attention to that.
331s are historically a couple hundred more when pricing kits because (most likely because they sell less of them).
There are some who believe 331 will have a longer life span than a 347 for a number of reasons that people like to argue about in discussion forums (rod ratios, piston rock at the bottom of the skirts, oil usage) etc....
With all that said....I have a 347 sitting on the stand that I'm installing in my 67 hopefully tomorrow
331s are historically a couple hundred more when pricing kits because (most likely because they sell less of them).
There are some who believe 331 will have a longer life span than a 347 for a number of reasons that people like to argue about in discussion forums (rod ratios, piston rock at the bottom of the skirts, oil usage) etc....
With all that said....I have a 347 sitting on the stand that I'm installing in my 67 hopefully tomorrow
10-02-2013, 09:06 PM
#3
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Yeah, engine longevity is really about the quality of the parts and the way it's built. Similarly done, a 331 or 347 will last just as long.
So what it comes down to is use, if you plan on turning a lot of rpm frequently, let's say a lot of road racing...then a 331 might be better for you. If you can't afford the heads for a 347, then a 331 will make power at a higher rpm than a 347 with the same heads....so that's a matter of gearing and what heads you use.
In the end though, more cubes = better, and if you spend the money on parts for performance, then you can turn 7k in a 347 on pump gas and still get a couple hundred thousand out of it.
Or you get an aftermarket block and build a 363 or 374.
So what it comes down to is use, if you plan on turning a lot of rpm frequently, let's say a lot of road racing...then a 331 might be better for you. If you can't afford the heads for a 347, then a 331 will make power at a higher rpm than a 347 with the same heads....so that's a matter of gearing and what heads you use.
In the end though, more cubes = better, and if you spend the money on parts for performance, then you can turn 7k in a 347 on pump gas and still get a couple hundred thousand out of it.
Or you get an aftermarket block and build a 363 or 374.
10-04-2013, 07:09 AM
#6
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Hi,
A 331 is capable of making more than enough TQ and HP for you to squander. It's about paying attention to the quality, the proper combination of heads, cam, and intake. Mine will spin to 7K, with 6800 is usable and makes 400 RWTQ at 4200. The quality and installation of the cam, valve train, and heads allows this. It's a full roller, as well. Don't forget a 3.55/3.89 rear is nice too. This is, if you're running an T5 or AOD. Happy trails.
A 331 is capable of making more than enough TQ and HP for you to squander. It's about paying attention to the quality, the proper combination of heads, cam, and intake. Mine will spin to 7K, with 6800 is usable and makes 400 RWTQ at 4200. The quality and installation of the cam, valve train, and heads allows this. It's a full roller, as well. Don't forget a 3.55/3.89 rear is nice too. This is, if you're running an T5 or AOD. Happy trails.
10-05-2013, 08:23 AM
#8
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Interesting. I assume your 331 has a forged crank if you're turning it that high. Did you build it yourself from scratch, or is it a crate engine? The reason I was looking at crate engines is that I calculated how much all the necessary parts would cost to build one from the block up, and places like Blueprint Engines have almost-complete engines for not much more. Plus..I don't have a shop or the necessary tools to do it all myself. I can do all the minor stuff here in my carport (changing intakes, water pumps, etc.) but to build a complete engine, I'd have to pay somebody..hence more expense.
And yes....had planned to go with a hydraulic roller cam, for sure...aluminum heads, too. My transmission is a wide-ratio Toploader 4-speed that was just completely rebuilt last week, so it should be good to go for a long while. By the way...got all my parts from David Kee in Texas, and am really pleased with the quality, price and customer service (in case anyone is planning on re-working their Toploader!). Rearend ratio is 3.50. What I will eventually be looking for is something about like what you have....a solid, strong-running 331/347 turning out around 350-375 HP, with no more than 10:1 comp. Nothing overly extreme or too temperamental to run on the street.
And yes....had planned to go with a hydraulic roller cam, for sure...aluminum heads, too. My transmission is a wide-ratio Toploader 4-speed that was just completely rebuilt last week, so it should be good to go for a long while. By the way...got all my parts from David Kee in Texas, and am really pleased with the quality, price and customer service (in case anyone is planning on re-working their Toploader!). Rearend ratio is 3.50. What I will eventually be looking for is something about like what you have....a solid, strong-running 331/347 turning out around 350-375 HP, with no more than 10:1 comp. Nothing overly extreme or too temperamental to run on the street.
10-05-2013, 01:44 PM
#9
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You can turn 6,500rpm safely with the Scat cast cranks, the block will fail first. Some people say they rate them conservatively and turn 1,000 more rpm with 100 more hp than they're rated, without issues.
If you're building an engine from scratch, just go 347 unless you plan to race in a class that has displacement rules, or you want something kinda mild that you can turn high rpm on the track all day with a lower budget.
And spend the money on good parts if you want to make power and have it be reliable, don't expect a $5k crate engine to last long on a track if you run it hard. $10k will get you a 500hp 347 that will last a really long time and take a ton of abuse.
And don't be afraid of compression either, 10-11:1 on pump fuel is easy to do these days with a well built engine. More compression means more efficiency.
FWIW my next engine is going to be a track reliable 363 ~550hp. But that's down the road, and costs $$$.
If you're building an engine from scratch, just go 347 unless you plan to race in a class that has displacement rules, or you want something kinda mild that you can turn high rpm on the track all day with a lower budget.
And spend the money on good parts if you want to make power and have it be reliable, don't expect a $5k crate engine to last long on a track if you run it hard. $10k will get you a 500hp 347 that will last a really long time and take a ton of abuse.
And don't be afraid of compression either, 10-11:1 on pump fuel is easy to do these days with a well built engine. More compression means more efficiency.
FWIW my next engine is going to be a track reliable 363 ~550hp. But that's down the road, and costs $$$.
05-03-2014, 01:23 PM
#10
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Hey Dodgestang....did you ever install that 347? If so, how is it? Like I originally posted way back..I'm still in the process of deciding between a 331 and a 347. So far...am leaning towards a 331. Probably one from ATK. Still at least a year down the road, though...you know...$$$..!!