The Stovebolt Site Forums The Shop Area Engine Shop aluminum pistons rods

Has anyone out there ever tried aluminum connecting rods in a straight 6, 292 in particular? Pros and cons anyone.

I don't think they are worth the effort unless you need / want to change the rod length (stroker motor or moving the pin up on the piston).

If you go with new pistons from Ross or Arias and get your stock rods reconditioned (Speed-o-Motive is a good shop) you will have plenty of strength for reving to 6000 rpm (which will require a lot more than new pistons).

If you decide to go with aluminum rods you will have to grind notches in your cam shaft for clearance of the studs / end caps. You will also need to grind clearance on the inside walls of the crank case down where the pan meets the block for room.

Aluminum rods also flex more than steel rods and elastically stretch at high rpms a few thousands of an inch requiring much more attention in the combustion chamber to make sure you dont hit valves or have too small a quench area where collisions might also occur.

The highest stresses a rod sees are at the end of the exhaust stroke / beginning of the intake stroke (decelerating the piston at TDC). If the piston you choose is lighter than the stock piston . . . your stock rods will have significant margin for about any application unless you are shooting for race only performance.

Thank you Ken,
I think I'll stick with my old rods. I don't plan on revving my six past 3500 once I'm done building it. By the way, what all is done to recondition Rods and when is it necessary to have them done?

Rods for a non race engine can be resized by your local machine shop for 15-20 dollars each.The rods are checked for fatigue and straightened if necessary,the cap on the big end is milled slightly and the bore is resized for proper bearing crush.If a forged steel rod is used for hi performance,you may want to have then shot peened or similar surface stress relieving treatment.

New rod bolts should also be installed during the recon process. Have shop pay attention to width of big-end, as it controlles rod side-clearance to crankpin and factors into oil throw-off. Rods, pistons, crank, flywheel and crank damper should also be balanced.

62 stepside,

You wouldn't happen to be asking this question because of this Ebay auction would you...???

What do major pro engine builders say from actual experience with alloy rods in a street engine.British bikes used aluminum rod for 40 years,they have their problems for sure, but conn rod failure isn't . I have no clue, dah.And about the rod bolts,how many of our 235/261's and GMC's have new rod bolts? Do they actually fail over time? Are all our old Stovebolts like ticking bombs? This could be horrible,235's throwing rods left and right, the price for replacement engines skyrockets as supplies dwindle.Soon all the newer six's and V-8 are scooped up and the whole Stovebolt experience implodes , the resulting black hole sucks in every vehicle in the world.Plunged into the dark age cause you guys won't replace your rod bolts!!!

Wow,
I'm grounded again, Thanks Tony!!LOL
BTW Tony, Less Caffeine!!
Take care all, and thanks for the input,
Bo