Clevelands and FE are done, will start my first 5.0 !

[blykins]

So what are your arguments against the 347? I've never sold a 331 or even built one. The 347 components are the same price and I've never had an issue with oil consumption or piston instability, even on 347 drag race engines.

I'll send you a price on a custom HR 600.

[westcott cobra]

Brent,
I just dont like the technical solution because I'm a nitpicker and born in May what means I'm a Taurus and have all the negative characters comming with this constellation

To be serious, I'm always do "robust engineering" during my job and do so for my private projects, even if there is no real issue with most 347 piston designs I won't do it that way. It is my way to add some theoretical safety not to go to the limits my engine border lines allow to do.

Too complicated german thinking? Maybe

Uwe

[blykins]

Originally Posted by westcott cobra

Brent,
I just dont like the technical solution because I'm a nitpicker and born in May what means I'm a Taurus and have all the negative characters comming with this constellation

To be serious, I'm always do "robust engineering" during my job and do so for my private projects, even if there is no real issue with most 347 piston designs I won't do it that way. It is my way to add some theoretical safety not to go to the limits my engine border lines allow to do.

Too complicated german thinking? Maybe

Uwe

What theoretical safety limits are imposed by going to a 3.250" stroke versus the the 3.400"?

The only time I would pass on the 347 for the 331 is if I'm building a stroker engine based on a 289 block that potentially has shorter cylinders.

There's no way of implying a safety factor into an engine where the cast stroker crankshaft will take more horsepower than the factory block that you're putting it in. I've seen factory 302 blocks split in half at 450hp.

[westcott cobra]

The 347 pistons are more to the parts limit then the 331. That's my own definition and view of the different piston designs.

I'm not angry about different stroke length, i just don't like the design of the 347 pistons, that's all.

The 331 has hands down.

I always appreciate different opinions and experiences others made to learn from, all day. I will also learn from all your input and I like controversial discussions but I definitely will not build a 347.

The nitpicker deep in me tells me everyday NOT to exceed my total budget for the MK IV restoration. I need a lot of money for the complete car to bring it to the standards i have in mind. If i allow myself exceptions here and there at the end the total will be some thousand USD higher then planned.

Look at this poor car, it needs a lot of love and for sure a lot of money.....

[blykins]

If pricing is a factor, the prices are the exact same between the 331 and the 347 rotating assemblies.

It's just hard for me to swallow topical arguments like this. If anyone has to worry about safety factor, it's a professional engine builder. If a part fails, an engine smokes, etc., it's basically a mark against their pocket book and reputation. With that being said, knowing that my engines put food on my family's table, I would always opt for the 347 over the 331. I would never turn down stroke and displacement for a street engine. A broader torque curve does nothing but help the cause, especially in a smaller engine.

There's nothing wrong with nitpicking, I just like to have a sense of logic behind my viewpoints. That may be the German in you, but it's the Mechanical Engineer in me.

I would consider changing one or more details of your build if you're looking for the power numbers that you're looking for. The 165cc heads combined with a super small camshaft will do a lot for torque, but won't give much in the direction of horsepower.

Of course I'm assuming that you posted all of this asking for help on achieving the goals that you've lined out for yourself. A lot of guys post, asking for help, but argue with everything that is said.

[westcott cobra]

Sure I asked for support, unfortunately 2 facts are given because they really exist right now.

1. 165 AFR KC CNC ported heads are here since 6 weeks, imported, taxed, paid, no one here will buy these heads because nobody knows AFR here They were planned to refurbish a full emissions "california" factory 5.0 HO from 85 in my Cobra.
I tried to sell them.... no way! So, they have to go on my new engine.

2. 331 short block was defined and is ordered, they work on it.

Everything else is not finally decided and can be changed to hit the target for a smooth idling small block with as much torque as I can get with the 2 fixed parameters above.

My Clevelands had different characters, the first one was build for torque the second one in different evolution steps was made for a rpm limit of 7k and it did so.

To be honest, i liked the rpm/hp Cleveland more because you could hunt Porsches on the highway up to 165 mph and you could fight with fast motorcycles on curvy country roads til they gave up.

I enjoyed the horses in the higher rpm range always because they where straightforward and predictable for me as the driver.

But ask me what made more fun without going real fast, always the Cleveland made for torque.

I'm far away from arguing everything and I hope this will not stop you from giving ideas and sharing opinions on cams, intakes, carbs and so on.

Uwe

[Mark O'Neal]

Originally Posted by westcott cobra

The 347 pistons are more to the parts limit then the 331. That's my own definition and view of the different piston designs.

No they're not.

But, assuming it's a worry to you, run a 5.315 rod in the 347 and then it's exactly the same piston.