For information...how much torque and Hp can a stock rod big block can handle ?

Dan

I went 9.80’s @ 2800 pounds over 25 years ago but I throw them on a he scrap pile now and buy better rods. I did change out the rod bolts for Dirrect Connection ones and did some grinding on the beams.

Rating connecting rods by HP and torque is completely a marketing trick.
What breaks rods is reciprocating weight times RPM as the piston passes through TDC on the intake stroke, and it would happen with the ignition off.

I’ll add that my engine had a stock crank and very heavy TRW pistons. We didn’t have many choices back then.

The stock rods are pretty good around 5800, past 6200 rpm things get worse. If you plan on higher rpms then that on a regular basis, after market rods for sure.

Sure they can be zinged up to 7200, 8000 rpm and survive, like in the water box by accident. But you surely don't want to race them at those rpms

4.56 gears, 14-31 slick. Never broke a rod but after 3 years of racing twice a weekend every crank I had magnafluxed during rebuild had cracks

I have an old 440 that was my first race motor in my 63 Plymouth, it is a cast crank LY rod engine with TRW's, belted the living daylights out of it running a best of 9.69 @ 135 with a small shot of gas. It has had a sleeve fitted to one cylinder after a pin walked but this engine still lives and is a 10.90 deal in my sons street valiant.

Cast Crank LY rod action
https://www.youtube.com/watch?v=nt4DpdAI7Fk

440 six pack rods fitted with .990" bushings using Ross pistons. 9.90's at 6,800 rpm with a four speed for many years. Never hurt a rod. I have broken DC rod bolts in the past. Wouldn't consider anything but ARP now.

'69 Cuda, 3000lbs 14x32, 4.88's, Stock blueprinted 440 6-pack motor, polished beams/shot peened good bolts on rods, turned 6600 NA, 7000 w/125hp N20, 7300 w/150hp N20 to run 9.96. No issues, had external oiling, but wouldn't hit that 7300 run more than once, didn't like the song the motor sang at those rpms.

Depends on piston/pin/ring weight and RPM. Light stuff below 6500 with good bolts will go a long time.
Doug

Steel rods can be tortured many times, and come back to fight another day.
An aluminum rod, once stretched, is a ticking bomb.

Stock rods break after many many runs in the 6.50s

Woww!
They are that strong ? So they should live long in a 650hp motor ?

440 source sells a set for 250$......hummmm what to do ?

Dan

But are the Source rods as good as the old LY's ?? Not sure.

If it was me I would spend a few extra bucks and see if Scat offers a big block rod. I had a set of Scat small block rods I bought in a package deal and they looked real nice. Very reasonable too. At least they come with 7/16 rod bolts. it cost a fair amount of money just to prep the old stock rods.

In case you missed Polyspheric's earlier post above.



Kevin

Also, what Poly left out, was duty cycles, miles/rpm over the rods lifetime. That's most likely a unknown. Are they at the end of their life cycle or somewhere in between.

So these new rods....what would they take in average 451 weight ?

Dan