331 vs 347 stroker motor

You need to SPECIFY that you want the 5.315/5.325 short rod version if you want it. Otherwise you'll get the less expensive but more popular 5.4 rod version of the 347 kit.

Whose piston did you use on the 331 - not much reason for that one to punch through - but the blower slugs will force the ring belt down to get clearance for a dish. Another good place for that shorter rod...
[addsig]

A friend of mine just did a 331 and the main reason this decision was that it did not require any block notching where as the 347 needs to have some block massaging for the rotating assembly to do its thing. The 331 revs nicely and has more power and torque than the 289 it replaced. If I still had my of '67 'stang with the 289/4 speed, I would have definitley gone with the 331 for the replacement engine.

Originally Posted by coolreed

The main problem with the 347 is that at higher rpm the piston puts higher than normal pressure on the side of the cylinders compared to a 331. This is due to the longer stroke and rod ratio.

And a 331 places 'higher than normal' (wtf is normal?) pressure on the side of the cylinder than a 302, and a 302 places 'higher than normal' pressure on the side of the cylinder than a 289.

I'm failing to see the relevance =).

Guess the 3.6" stroke 302 I was gonna do will be a pile of junk =D.

Better scrap that idea!

Cris

Cris, My rod is too long. It puts too much pressure on the sides of the cylinder. What you need to do is build your 3.6" stroke 302 with a 5.090 rod so it will run faster and last longer. LOL!

Originally Posted by leethal72

Cris, My rod is too long. It puts too much pressure on the sides of the cylinder. What you need to do is build your 3.6" stroke 302 with a 5.090 rod so it will run faster and last longer. LOL!

Hell, I'd be happy if I had a 5.09" rod!!





Anyhow...

Better yet, 347 via: Boss 302 block bored 4.125" X 3.25" stroke and 5.315" rod.

Larger bore = unshrouding the valves better.

Short stroke = better rod/stroke ratio (if you really care), and more importantly, shorter rod = better piston compression height.


Note: 331 piston for 5.4" rod is the same exact piston used on 5.315" rod 347.

Originally Posted by coolreed

The main problem with the 347 is that at higher rpm the piston puts higher than normal pressure on the side of the cylinders compared to a 331. This is due to the longer stroke and rod ratio.
But many have successfully utilized the 347. Personally, I have chose the 331 for my Mustang and had good results too. After doing alot of research and talking with many experts I decided on the 331.

I would say you have talked to the wrong experts.

Do the 347 and dont worry about rod ratios, build the 331 if you want less power.

Originally Posted by 87stang

Note: 331 piston for 5.4" rod is the same exact piston used on 5.315" rod 347.

Good Post!

Rod ratio.......Ya, there is something to be worried about! LOL

HE HE HEH EHEHEHEEHEHHHH You said rod HE HEHEHEHEEHH yeah yeah !

i also used the 331 and track resting proved to good <with over 50 passes at 123 mph and 10.67 on most ! strong and fast .