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86 newbie 12-02-2011 10:37 PM

331 and 347 questions
ok i have a stock 302 block and wanna make a stroker. What is a 347? is it still the 302 block bored to max or is it another block. If its the same block then what makes it the 347 also whats the bore on it and a 331?

tinman 12-02-2011 11:19 PM

A 347 is a 302 bored .030 over and fitted with a 3.40" stroke crankshaft with the correct pistons and rods.
A 331 is also a 302 bored .030 over and using a 3.25 stroke crank with the correct rods and pistons.
You really can't bore a 302 block past about .060" and have any degree of safety as far is block life goes, even then not all 302 blocks can go that big......

86 newbie 12-02-2011 11:35 PM

ok thank you that helps a ton! is there a certain brand thats good for the 347 stroker kit?

86 newbie 12-02-2011 11:37 PM

also if you have to bore a 302 block out to a .40 over can u still use the 3.40' crankshaft and still be a 347?

Venomantidote95 12-03-2011 04:07 AM

U start spliting hairs then 348 349 lol you still basically have a 347...

Venomantidote95 12-03-2011 04:10 AM

You have 2 rods to choose from 5.4 or 5.315 that affects piston hiegth and choice.

AdderMk2 12-03-2011 05:07 AM

have someone build the engine for you.

86 newbie 12-03-2011 02:35 PM

thanks guys and adder i want to build it, thats why im asking,i asked because i wanna learn and so forth

tinman 12-03-2011 10:52 PM

There's a lot of good places to buy the kits from.
One bit of info however, someplaces will tell you it's a balanced kit or they will balance it for $75 or something.
Thats B.S. unless they have the harmonic balncer and the flexplate/flywheel that you're going to be using.
I would aviod the big mail order places like Summit and Jeg's simply because there prices are higher than than some of the smaller places.
I've done a couple engines and I got the rotating assembly from Coast High Performance in California. They have good service and fast shipping. They are part of a company that makes forged pistons so if you want a specail relief or anything like that they are good with it......

Venomantidote95 12-04-2011 07:57 PM

There are people here that can help u just ask if everyone paid someone else many of us wouldnt be here on the forums or have the cars we have.... Good luck! As stated dont get the kit prebalanced for many reasons.

tinman 12-04-2011 09:54 PM

Remember also that you'll need good heads and a cam that's different for either the 331 or 347 engines.
302 parts make 302 power and that is not what you're looking for.
Trick Flow, AFR, Edelbrock all make good useable heads for 331/347 engines.
Comp Cams has new stuff on the shelf for them also.........

86 newbie 12-07-2011 07:11 AM

ok thanks i looked at comp cams website and i think i might go with the 35-776-8 cam. its a good street high RPM hp and torque cam

89stang1 12-07-2011 07:22 AM

you will make very similiar power with either 331 or 347, im very pleased with the comp cam im running

86 newbie 12-07-2011 05:14 PM

ok, what kind of cam are you running?

im_stuck_in_iraq 12-07-2011 06:09 PM

ugh i want a stroker...

tinman 12-07-2011 11:18 PM

It's a very cost effective way to go IMHO.
Not real cheap but maybe the best.
Really figure about $5000 by the time it's all built, balanced and machined.
Price would be about the same doing something like a 408 instead of a 347.
I've included buying everything new in the prices, if you can find 'deals' someplace that's good too.......

Venomantidote95 12-08-2011 01:36 AM

Pending yr its not the same money doing a 408/347 not even close. The 776 is a great cam I used it in my buddies 331 he loves it. My 347 topend included 3500$.
im running the 35-556-8 and its awesome good n/a power and loves the gas!

86 newbie 12-08-2011 09:30 PM

alright sounds good, what cc heads do you guys think i should get i want AFR but im not sure yet what kind

Venomantidote95 12-08-2011 10:39 PM

347? Pending use 185s.

86 newbie 12-09-2011 11:32 PM

ok lol

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