Quick question

[Garys1969RR]

Wow, I just looked up the weight on those 2355 pistons, they're coming in at a whopping 1097 Grams with the pin! Ross dome pistons, with a Chevy pin, for a 451 weigh 696 grams. That's one nice thing about reduced C Height. No wonder that motor will rev to 3000 RPM almost instantly! At 3000 RPM, the piston is changing direction 100 times a second. Reduce reciprocating weight as much as safely possible.

 

[wyrmrider]

The six pack rods never came with a cast crank or a cast crank never came with 6 pack rods
I agree with the suggestions to go with LY rods
I built one motor with the 6 pack rods and it did not rev freely
there is a member here who has a stroked 400 out to 451 and evidently it revs really well, which has been my experience with stroked 383, 400, 440's
stock stroke 440 should rev like a 440 crank in a 383 or 400 which is, to say, good using LY rods and light pistons
have you tried the rear gear swap yet?

 

[Garys1969RR]

The 440 has a Compression height piston of 2.067, best case. So that makes for a large, bulky, heavy piston. Put that same 3.75" stroke crank in a low deck block, with the 440 length rod, and Voila! You have a C Height of about 1.320". So the piston resembles a (dare I say it) lightweight small block chevy piston. And we know how well those things rev! That's just one of the many benefits of the 451 type motors.

 

[Garys1969RR]

440 piston with 2.061 C H.

Now that's a BIG PISTON!

 

[SimDog]

Actual picture of the SP pistons

 

[Garys1969RR]

Yes, the long skirt of the 2355 is not only heavy, it also increases friction on the cylinder walls, robbing horsepower.

 

[mopar 3 B]

Yes, the long skirt of the 2355 is not only heavy, it also increases friction on the cylinder walls, robbing horsepower.

Really! Ford had more than its share of problems with short skirt 460 pistons. GM has always had problems with cylinder wear do to short skirt pistons.
You want to shorten the skirt decress the displacement.

 

[Garys1969RR]

Yep! Less friction, it only makes sense. Of course there are other issues that can arise. My 451 with a relatively short skirt Ross piston, had no issues and ran great!

 

[mopar 3 B]

Yep! Less friction, it only makes sense. Of course there are other issues that can arise. My 451 with a relatively short skirt Ross piston, had no issues and ran great!

Like the way you stated that. "AND RAN GREAT"
Has it quit running?

 

[Garys1969RR]

Still running great after many hi way miles, and almost a hundred low 12 second passes down the 1/4 mile .

 

[wyrmrider]

where the short skirt pistons have a greater challenge is with a short rod/ long stroke

 

[Garys1969RR]

where the short skirt pistons have a greater challenge is with a short rod/ long stroke

Yes, I agree. The question is, what is an acceptable rod length to stroke ratio? 1.8 seems to work well, but 1.6 and less seems to create problems with a short skirt piston. I like the 6.76 LY rod with the 3.75 stroke, rather than the shorter 383 length rods. The 440 rod gives a nice 1.81 ratio with the 3.75 stroke. The 383 rods place the ratio closer to 1.6.

 

[wyrmrider]

You are absolutely correct- much less side thrust and easier to dial in a cam
only place short rod works is as a crutch- maybe 2 bbl or restrictor plate or something else special

 

[dvw]

Pick your stroke. Find a piston that works. Connect it with a rod that fits. Rod ratio is pissing in the wind. Look at some BB Chev stroker rod ratios. You'd fall out of your chair.
Doug

 

[wyrmrider]

That's one way to do it
keep your revs down or it won't last
You are really head limited with those builds which helps so you build for a big fat torque curve
what's not to like
tires and rear end and tranny
great for wheelstands