dfw

blownaltered · 12-03-2013, 08:17 PM

Originally Posted by Toby

I will agree the ls gets better mileage, but apples to apples they cost about the same to build with similar hp results. I have built a bunch of both, my ls1 in the truck actually ended up costing more then My 347 in the mustang. I doubt he is much worried about fuel mileage if he wants a big hp car. It's is nice but doesn't always come with the territory. Different strokes man.

A short stoke 347 with the proper cam, heads, intake with a little boost from that monster blower will easily make 600-700 and drive smooth as can be.

What rods and pistons would you use with a short stroke 347? Would that be a 331 rod with the bigger 363 pistons?

**Toby** · 12-04-2013, 01:06 AM

Originally Posted by blownaltered

What rods and pistons would you use with a short stroke 347? Would that be a 331 rod with the bigger 363 pistons?

Yes and no. A 347 and 331 both use the same rod but the compression height is different thus different pistons. normally you would use a 3.25 stroke crankshaft, along with a 5.4 rod and a 4.125 bore piston. Personally I would use a 3.25 stroke crankshaft, a sbc 5.7 rod, along with a set of custom built pistons that have the correct xompression height that will put you at a zero deck and 4.125 bore. Reason for the sbc rods, is because they are readily available and having the longer rod gives you a better rod angle thus less side load on the pistons and less pressure and friction on the cylinder walls which could equal a smoother runing engine that will last longer and make more power. but you will need to get a crank that has the rod journal cut to fit the 2.1" sbc rod journal rather then the conventional 2.123 sbf journal. most of the parts will be easy to get ots parts except the pistons. they may need to be custom made but i would have to do the math to figure the compression height needed along with the correct pin size, and ring placement and thickness for the application. I will have to do the math later but it would make a killer combo IMO!!

**STROKD** · 12-04-2013, 04:05 PM

What Toby said... i have basically that setup going in my car but it is a long rod big bore 351 instead of a 331... (374 cid vs 347). same concept, just larger block with a tad more stroke 3.5 vs 3.25.

blownaltered · 12-05-2013, 01:09 PM

Originally Posted by Toby

Yes and no. A 347 and 331 both use the same rod but the compression height is different thus different pistons. normally you would use a 3.25 stroke crankshaft, along with a 5.4 rod and a 4.125 bore piston. Personally I would use a 3.25 stroke crankshaft, a sbc 5.7 rod, along with a set of custom built pistons that have the correct xompression height that will put you at a zero deck and 4.125 bore. Reason for the sbc rods, is because they are readily available and having the longer rod gives you a better rod angle thus less side load on the pistons and less pressure and friction on the cylinder walls which could equal a smoother runing engine that will last longer and make more power. but you will need to get a crank that has the rod journal cut to fit the 2.1" sbc rod journal rather then the conventional 2.123 sbf journal. most of the parts will be easy to get ots parts except the pistons. they may need to be custom made but i would have to do the math to figure the compression height needed along with the correct pin size, and ring placement and thickness for the application. I will have to do the math later but it would make a killer combo IMO!!

Now that sounds like something I would be interested in. I like the sound of that combo. How hard would it be to find a crank with those specs?