[fiveliter8]

Allright,
I've been a gearhead for some time now and have always heard the term beam-ground, shot-peened, relieved and balanced rods. What the heck is beam-grinding and shot-peening and how does it help performance-wise? Is $200 dollars for a set of stock 351W rods with all this work done worth it? Thanks,

 

[LuisO]

I think shot-peened means that they actually shoot pellets or shotgun ammunition type media at the rods, like if they were sandblasting it. This "compacts" the rod material all around, making it less prone to cracks due to cast fault (empty spaces) when the rod was made.

Again, this is my understanding, I may be wrong though.

Luis.

 

[DragonSnake]

Here goes nothin':

Beam Grinding: A forged steel rod will have a raised forging mark that runs along each side of the rod beam. This can act as a concentration point for internal stresses, and can give cracks a place to start. Grind this off, and polish the beam with your die grinder to eliminate this stress riser.

Shot Peening: Basically, you "sandblast" the rod using steel shot instead of sand. This gives a more uniform surface hardness and density, also reducing the risk of cracks starting.

(Stress) Relieved: I'm not sure on this one, but probably involves heating the rod at moderate temperatures to releive internal stresses created when the rod was forged.

Balanced: Making sure each rod weighs exactly the same. You also weigh each big end and each small end to make sure they are the same.

Are there any metallurgists out there that can explain the first 3 better?

$200 for a full set of rods, with all of this work done, and resized is probably a good deal.

-Joe

 

[Macho Toy]

Originally posted by DragonSnake:
Here goes nothin':

Beam Grinding: A forged steel rod will have a raised forging mark that runs along each side of the rod beam

-Joe

I thought that it was the cast rods that had this line. Doesn't forged mean that they are formed (pounded, ground, drilled, etc.) out of an ingot to a nice smooth finish?

Take care,

 

[DragonSnake]

Dan,

Forging is the process of "hammering" a piece of steel into a desired shape. Small block Ford rods are forged. The ridges that exist along the beams of the rods are where the two pieces of the forging die separate. Kinda like the "seams" in our FFR bodies.

Cast pieces will have "casting flash" which is essentially the same thing; metal that sqeezes out between pieces of the mold.

-Joe

 

[PSB]

Stress relieving is a heating process that reduces the internal stresses in a part. An unfortunate side effect is that it also softens the metal. So, you then shot-peen it to harden it back up again.