331 or 347?

[daveSanborn]

This is always a good topic. Let's get something going here about the pros and cons of each.

My thoughts are to go with the 347. So what that it has a propensity to burn a little bit more oil and there's an increased piston wall side load. When it wears out, replace it. Get the most bang for the buck and if/when it goes "bang", fix it.

What are your thoughts/preferences?

 

[Waffles]

408.

 

[Fast68back]

I've heard that oil issue had been resolved, that it was mainly the earlier stroker kits that had that issue? If I were building from scratch I'd build a 427.......It just sounds cool. 331 sounds kinda gay. 347 is ok, like people would say wow, its almost a 350 or something. I usually tell people I have a Briggs&Stratton, 4 stroke, you'ld be surprised, most folks are impressed by that..

 

[daveSanborn]

I've heard that oil issue had been resolved, that it was mainly the earlier stroker kits that had that issue?

If the depth of the wrist pin intersects the oil control ring groove, it's going to burn some oil. To get around this, slightly shorter connecting rods are being used. A standard 347 rod measures 5.4". This rod usually intersects the pistons oil control ring groove. Slightly shorter rods are available to move the wrist pin out of the oil control ring groove, 5.35" is an example. With a shorter rod though comes less stroke, less stroke = less cubic inches.

 

[Starfury]

Eh, it's not as big of an issue now as it used to be, even with the intersecting wrist pin. Piston/ring manufacturers came up with some pretty cool new oil ring designs that prevent a lot of oil bypass. The other options are to relocate the oil ring land above the wrist pin bore, and to use a shorter rod. The downside to relocating the wrist pin bore is that you end up with a VERY short piston, which reduces piston stability and can lead to piston slap later in the engine's life, especially if it's a high-hp engine. The downside to a shorter rod is that you now have an even worse rod ratio (already crappy on a 347), creating a lot of wear on the sides of the piston/rings and cylinder. Shortening the rod, however, doesn't change the stroke Stroke is strictly a function of the crank.

I have a 331 and I love it. I also have 5.4" rods and special pistons on my 331 because a) the price was right, and b) long-rod engines build more torque at lower rpm's, which is what you want for a street motor. It does burn some oil, but oh well.

If you want to build a street motor, 331 is the way to go. It will wind up slightly faster than an equally-built 347, power difference won't be much, and it'll last longer due to the improved rod ratio. With my longer rods, my rod ratio is is even better. I built my engine to last

If you want the most power you can get and don't care much about engine life, go for a 347. I'd recommend sticking with the standard 5.4" rod and using the special oil-control rings, due to the downsides of the other options I listed above. With a good build, you can still wind the piss out of a 347 and make some scary power.

 

[68EFIvert]

Heck who needs to stroke it. Jut put a blower on. I have a fairly mild 302 with over 400 rwhp and rwtq. I don't have to worry about rod ratios one bit. Now that I said that. If I ever blew the motor I would go with a 408 or 437 stroker and put the blower on. That would be one crazy fast ride. ;D. I think I have traction problems now I could only imagine what 550-600 rwhp would feel like.

I would place my vote on 331 over a 347. Mainly on what I have heard about reliability and running a blower would put much more stress on the combination than NA.

 

[Sluggo]

I've heard that oil issue had been resolved, that it was mainly the earlier stroker kits that had that issue?

If the depth of the wrist pin intersects the oil control ring groove, it's going to burn some oil.

You mean like this? my shit don't burn no oil.