347 Piston Rock Issues ?

KevinM · #1 (**permalink**) 10-29-2006, 06:36 AM

Over the years, I have been told by several engine builders that they like the 331 better than the 347 (In a stock 302 block) for a daily driver because of the piston rock issues with the 347.

Supposedly, because the piston comes a fair way out of the bottom of the bore and rocks, it causes more ring wear, etc. This makes good sense, except that I have never heard anyone actually report having any problems related to this.

So my question, for those of you with 347s that have a lot of mileage on them is: Have you had any wear problems of this type, or has the engine been fine?

Thanks,

Kevin

flyboy1997 · #2 (**permalink**) 10-29-2006, 09:10 AM

Not high milage yet,3000 maybe, but everytime You see the motor in a Catalog it says " Not recomended for a daily driver". I thought it was because of thinner walls & heating issues, mine does not like parades & have black magics super fan, two row alum., fail safe, & March System? Wendell

jmarsey · #3 (**permalink**) 10-29-2006, 09:43 AM

Kevin,

The issue with the 347 is the rod angle. As long as you are not road racing you should get plenty of life out of this combination as a daily driver. If you are looking for endurance and sustained higher rpm then the 331 is the best combination for the 8.2” deck height.

Good luck, John

olddog · #4 (**permalink**) 10-29-2006, 09:05 PM

I have never owned a 347, but given it a lot of thought. It comes down to this fact for me. Ford decided that they needed a taller deck when they designed the 351 windsor. Unless you have to use the shorter deck to fit the car or race rules, why not use a 351 for a lot less money?

No doubt in my mind that the 347 rod ratio is so poor that if ran hard it will wear the cylinders into egg shaped holes. Those who race them likely pitch blocks frequently.