I'd recommend against ATK. I sell their engines at work and I haven't seen fantastic quality control from them. The last motor I sold to a shop had a dead cylinder caused by a bent valve. Another one that went to a machine shop had two cylinders bored .040 over, with the rest .030.

If you're not comfortable building it yourself, start talking to your local machine shops. They might cost a couple bucks more than a mass-produced product, but the peace of mind you get from an experienced shop checking for quality along the way is priceless.

 

The paint job took longer than expected....I am expecting to fire it up at the end of the month.

 

Hello;

sounds like a fun project. your gear selection is ideal for either engine imo.

The simple facts are that a 347 will not last as long as a 331. its not only simple physics, its my own personal experience of being in the business for many years. the people that try and argue about it simply lack experience and understanding if the physics. its a case where they a might have heard this or that or they might have had one of each at some point and neither one had a problem. well the problem with this is that they sold both cars after the engines only had 20k or so on them. well this is obviously not a longevity test. it might take 35k - 50k to see a difference in some cases, but yet, because of this one useless comparison they are suddenly experts. as many people say, "Well I read it on the internet so it must be true.", lol.

A 347 will have its power in a lower range than a 331.

if you want to feel like you have a ton of power then get a 347.

if you drive it every day and want long engine life then get a 331.

if you want max hp feel and just drive it on weekends then get a 347. its not like it will wear out in a year.

i too would not buy an atk engine.

as mentioned, don't be afraid of compression, you must have at least 9.5:1 static to get close to optimizing the engines performance ising 91 - 93 us rated ocrane gas.

the real compression you need to be concerned with is dynamic compression and cylinder cranking pressure. most people have no idea what these are and the budget ebay engine builders don't pay attention to these numbers and are sending engines out with less than optimal compression. thois is another reason it is best to have an engine custom built.

i general, the "bigger" the cam the lower the compression is. i know it does not make sense. this is because the bigger the cam, the later it closes the intake valve. the later the intake valve closes the less time there is for the engine to conpress the fuel mixture.

this is why cam mfg's recommend more compression for bigger cams.

 

Hey guys, thanks for the comments and advice. I'm still in the "research and decision" phase of this, so any and all info is more than welcome. It's going to be an expensive project, so I want to do it only once...and right!

Barnett...good points. I was already leaning towards the 331, and I'm now pretty sure that's what I will go with. I don't/won't put a lot of miles on the car, as it's only a weekend driver (maybe 4,000 mi/yr tops), but I still want soemthing that will hold up, and bark the tires whenever I want! The 331 seems to me my best all around option. And yes...do understand the cam/comp. ratio relationship. In fact, I once ran a 289 with 12.5 comp. on pump gas (for 4 years), but then it also had a cam with 300 degrees duration and lots of overlap (a Crane SSH-300NC grind if anyone is curious).

I also understand Starfury's point about finding a local shop to build one. In theroy he is right. But, my situation is, well, a little different. You see, here in Puerto Rico there's not many shops left that have any expertise with "old-school" V8s anymore. Here, most everyone is into those high-tech foreign jobs (like in those Fast & Furious movies). Plus...I've found that MOST mechanics here don't read English very well, and critical written instructions and specifications are frequently tossed aside. You know.."Instructions..I don't need no stinkin' instructions".

Then, if that wasn't enough...when local mechanics see a Gringo coming, they think "Ok..here comes money!" Prices get jacked up immediately. Sure ain't like back home in Tennessee! I do as much work on my car as I can (swapping intake, carb, water pump,etc.), but a full-blown engine build is beyond my expertise.

Hey..if anybody on this forum is actually in Puerto Rico, and knows a good shop, then do let me know.

 

My ebay- Tuff Dawg racing engine- is still in one piece after 2 years. I would buy from them again, but would prefer to go with a 351w base engine. Don't want to start a war, but I think a built 351 is a better bang for your buck. more cube potential (if stroked) and more power potential (N/A or power adder) than a 331 or 347.

Tuff Dawg sells a 331 and a 347. You can also have them further customize the engine to your liking. for instance I had a full ARP engine assembly kit sitting at home. I sent it out to them as well as had them change the cam. Very friendly and had great customer service.

 

Personally, I think what you stated is a valid point. Folks that want big torque potential, should start with big cubes. The smart money is choosing the correct combos, quality parts, and blue printing the assemblies.
Stating this, I built a 333, that dynoed 401 RWTQ @4200 Rs. it made 392 RWHP @ 6100.
needless to say, it's got enough "giddy-up" for me.

 

If your poring money into a new engine you might as well go all out and get a 363. They aftermarket blocks have put this motor above both the 331 & 347 as far as power and you don't have to worry about how much power you'll make down the road. It'll handle what ever you throw at it.