Hand picking a set of rods. How to.

[dr_hunt]

I'm going to use sbc as an example, but this applies to all oem rods.

 

When choosing to use oem rods, it's best to hand pick a set. Things to look for are.

 

1. small balance pads on both ends of the rods.

2. Absence of copper colored coating on either the big or small end of the rod.

3. Semi-smooth parting line along the beam of the rod.

 

Explanation of why;

 

1. The factory makes the balance pads overly large during production and when the rods are weight balanced the pads are ground off until they achieve weight. Rods with small balance pads have more meat in the rod than rods that have large balance pads. You want more meat in the rod rather than the balance pad, makes for a stronger rod.

 

 

OEM Small journal rods sometimes used in stroker applications are not desireable IMO. Small journal sbc rods are not as strong as large journal rods IMO.

2. The copper colored coating is a plating that is used when the rod was oversized. It is dipped and then resized. Scrap those rods IMO as the copper plating can cover imperfections otherwise visible on the rod.

 

3. Some people polish the beams and then shot peen them to identify cracks and releive stress risers, while imparting uniform stress on the surface of the rod.

[grumpyvette]

while all the above are good points to know,its been my experiance that use of most chevy stock type rods is wasted time and effort, and a bad waste of money,

WHY?

ITs mostly due too ,cost VS strength

most stock rods are not 4340 forged steel

most stock rods use a 3/8" rod bolt and nut design which is WEAKER than the 7/16" ARP cap screw designs available in even the lower priced rods

 

look

 

http://www.scatcrankshafts.com/

 

http://cgi.ebay.com/ebaymotors/Eagle-6-0-H-Beam-Connecting-Rods-SB-Chevy-CRS6000B3D_W0QQcmdZViewItemQQcategoryZ33623QQihZ009QQitemZ190193051211QQrdZ1QQsspagenameZWDVW

 

http://cgi.ebay.com/ebaymotors/NEW-SBC-CHEVY-5-7-H-BEAM-CONNECTING-RODS-350-400-SET_W0QQcmdZViewItemQQcategoryZ33623QQihZ007QQitemZ170188121520QQrdZ1QQsspagenameZWDVW

 

 

you can buy matched sets of 7/16" ARP rod bolt equiped rods made from 4340 steel for under $400

 

most are FAR STRONGER than any of the stock 350 connecting rods and will cost less

[dr_hunt]

Very true grumpy, aftermarket rods are certainly my pick, probably not scat or cat products, but very true. There will continue to be members that use oem rods and this is certainly usefull information for that instance when HP levels are 500hp or lower IMO.

[grumpyvette]

your totally correct,about making the best of a bad situation, but having gone the rod sellection route both ways and having seen the cost and results Ive gotten with reworked stock rods and aftermarket rods, I now pitch stock connecting rods in the dumpster rather than waste the time and effort.

rods normally fail when the rods rod bolts stretch, at high rpms, and a 7/16" cap screw rod bolt is easily 20%-100% stronger than a similar 3/8" rod bolt(remember theres several differant quality rod bolts like the L19 alloy, 8740, 8740 heat treated, ARP2000, etc.)

 

http://www.arp-bolts.com/Catalog/Catalog.html

 

Id also point out that many (ROD FAILURES) were not rod failures at all,

but the result of detonation damage breaking a piston and the resulting damage when the rods forced to try and compress a solid slug of aluminum

or a bent valve when valve float occures, or lack of proper luberacation when the oil systems not set up correctly,

no rods going to do that well, under those conditions.