Originally Posted by 347Vert
Just do the research on why Ford Racing chose the 331 over the 347 in their all out 530hp crate motor. You can argue with me, but I'm just supporting the philosophy of Ford Racing and I happen to think they know what their doing.
These are the kinds of statements that should NEVER be allowed in a technical forum. Ideals that are based off of regurgitation and no practical experience. ie Opinions. Opinions should be kept in the Lounge.
The 331 that you eloquently talk about is 4.125" bore x 3.100" stroke. This is 331 in^3 and that is the latest thing they are preaching.
Now, I worked for the Grandfather of 347, Mr. Ronnie Crawford. We built as many as 10 x 347's per week and the vast majority were with Wiseco pistons, cast cranks that were turned down 351W pieces and Crower Sportsman rods. Yes, 351W cranks widdled down. In 1992 - 1997 there were no cranks as you all have today. The point is, I have been around this junk for a long, LONG time.
For those of you who do not know who I am, I then went to work for the best Ford guys on the planet,"The Glidden's". The 3+ years I was there coupled with what I am still exposed today would boggle your mind. I saw more junk at Glidden's in 3 years than it would take the average guy 20 years to duplicate.
Anyone, and I mean ANYONE, who wishes to talk about rod length or rods to stroke is in over their head. The way IT IS DONE on the high end is you know the stroke, you know what the piston C/H must be, and WHATEVER IS LEFT IS THE ROD LENGTH
. If you put any more thought into than that you have wasted your time. The key to making power is the piston design.
Now if this guy wishes to speak with experience about pistons, then start a thread and let's go.
The folks who do not understand these engines basically are new breed types. They don't understand that the 400 SBC had a 5.565" rod from the factory with a 3.75" stroke. That is a 1.484 R:S for those keeping score at home. This was done in the 1960's, 1970's and into the 1980's with JUNK cast pistons. Funny how trucks, vans and passanger cars accumilated millions upon millions of miles with such a poor R:S ratio.
Then we have the most popular "performance" engine of all time, the BBC. Yes I am a SBF guy, but if you do not recognize this, then you are a fool. A 454 BBC was a 6.135" rod with a 4.00" stroke. That is a 1.534 R:S ratio. Boy, don't see GM fixing that problem either.
How about a 393 351W stroker? 5.95 rod and a 3.85 stroke for 1.546 R:S.
I can keep going.
This is classic misinformation and it leads to internet myths. These kinds of threads are where the mods should jump in and squelch the poor information. But when the mods don't understand this stuff themselves, then how can that happen?
Is there more side load with a 347 vs a CONVENTIONAL 331? Sure there is, don't be a fool, but can anyone in this room tell me how much side load is bad? What is the DELTA change in side load from a 4.030" x 3.25" x x5.400" with a conventional pin vs a 4.030" x 3.40" x 5.400" with an off set pin? And remember, the 400 SBC and the 454 BBC examples.
To continue with that, how many of you know that a 1.090" C/H piston has an off set pin? Not many I bet. Then when you using a support rail, when the oil ring fails, it is on YOU and NOT on the design.
If you have never done it, trust me you WILL fail as I failed the first 2 times I tried it back in 1993. But you know what? I learned from my mistakes and I fixed what I was doing wrong. I did not run to the internet and make false statements just to make myself look better.
If you have an engine that -16- in^3 smaller, then you are making less power. That is a fact. The only time to build a smaller engine is if you are racing in a class where a weight/in^3 break is in effect. Then sure, smaller ~may~ be better. But for the street, take the cubes.
That is why a 331 gets a bad rap, its not as good of engine.
Now you asked.......
IMHO, Opinions are for the Lounge.
Experience & factual data are what is needed in the technical areas.
If you allow opinions [such as the ring land on the 347] then that is what leads to misinformation. Talking R:S is for bench racing with Corona and has nothing to do with an engine, per se`. A short rod accelerates quicker, resists detonation better, fills the cylinder better, and all around is a better deal.
I am still searching for a vendor so I can sell a 357 in^3 in a 302 block. This would be an 1.040" to 1.050" C/H which is STILL BETTER than a SBC 434 piston which is a 1.000" C/H.
Magazines are comic books are nothing but ads. I have been there, I have been on that side, I know the crud that goes in there.
There are those of us who do it and those of us who read it.
I speak from first hand, experience.