83gtragtop

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http://www.fordstrokers.com/

Norm Peterson

Just a few thoughts

347 is less than 5% bigger than 331. Maybe 0.2 seconds difference in ET and 1.5 mph trap speed. How important is 16 cubic inches?

For any given rod length, a 347 will make them run at slightly greater angles. The 331 may have a few more rpm between the peak torque and peak HP rpms (a good thing).

With 3.73's in the axle, you'll probably have traction problems on the street with either engine size.

Unless you're rpm-limited by the valvetrain, a street or dual-purpose 331 is probably good for about 300 more rpm than a similar-duty 347 (based on mean piston speed).


Norm

urban_cowboy

I agree with Norm. I tend to not push the stroke and rod length to the extreme. You can make big torque improvements with a 331 over a 302. Same for a 351 stroker...I built a 383 instead of going 393 or 408. Frankly, I would have to build a tube chassis car with a link suspension to handle more than my 383 is producing.

Something to consider. I know they are expensive, and I do not know what your torque and horsepower goals are but Dart and Ford make a mean aftermarket block. They are super strong and can really give you piece of mind when you are building serious power.

MBDiagMan

From reading his original post I got the impression that he is looking for something more streetable and NOT a high RPM screamer. Making your torque peak at a higher RPM does not make up for less displacement as far as streetable torque goes.

Again, "there's no replacement for displacement." For a race motor there is lots of merit in a properly built 331, but for a street motor that is not to be expected to last hundreds of thousands of miles, the 347 is tough to beat.

Again, don't overlook the fun of having low speed torque. Nothing embellishes low speed torque more than a longer stroke or small diameter, full length headers.

AGAIN, it's very important to consider the engines USAGE. For a strong motor for the street, a properly built 347 would be really tough to beat.

Low and midrange torque makes a car fun to drive. Horsepower wins races. Take your choice.

JMD

I have checked into this a little. There are some folks who think that 302 blcks have cylinders that are .02" longer than a 289 block, others have measured this and do not believe this to be true.

.02 is 1/50th of an inch, IMO, even if the 302 blocks are .02 longer it won't make an appreciable difference anyway, in any case some have considered any difference of .02 in cylinder length to be within casting tolerances anyway.

I want to think that this is an urban legend that may have had some of it's origins in Ford parts departments...... (you can't use a 289 block for that 302 you want to build, you need to buy a new block).

I posted a thread about this a few months ago intending to spark some discussion...

Starfury

I've talked to people who have mic'd 289 and 302 blocks side by side and found no difference.

As far as streetable torque goes, the 331 setup I recommended is very streetable. I drive mine with 3.25 gears and a close ratio toploader. 1st is pretty tall, but with 3.73's and a T5, there won't be any issues with driveability. The Rhoads lifters really do improve low-rpm torque.

MBDiagMan

I believe that where this statement of same cylinder lengths comes from, is the fact that the last year or so of 289 production, they made the change to the cylinder length in preparation for the 302 coming along. Another variable in this is the fact that it is a cast edge, so due to normal core shifting it will vary slightly on both blocks.

Some time ago I measured a 302 block from a 70 1/2 Falcon and a 289 block with a date code in 1963 and found there to be almost an 1/8" difference. Was this simply from core shift? I don't know, it would take MUCH more data than the measurement of only two blocks to be able to say with any level of certainty. If I were more of a scientist, I suppose I would have written down the measurements and measured other blocks as the past few years have gone by.

It might very well be that folks that do such measurement in preparation for a stroker project are only interested in six bolt blocks. Research might show that the extended cylinders coincided with the introduction of the six bolt block. If this is the case and could be determined for sure, then all anyone would have to look for would be a six bolt block.

My $0.02,