258 ROD CASTING NUMBERS

[streetpirate]

i was told there are two casting numbers for 258 rods.
i know dino said he used the "707" rods

what are the two different casting numbers (needed to get some at the engine dismantler) and is there any difference? im thinking its just the rod bolts that are different between them, but i dont know

 

[tealcherokee]

i was told there are two casting numbers for 258 rods.
i know dino said he used the "707" rods

what are the two different casting numbers (needed to get some at the engine dismantler) and is there any difference? im thinking its just the rod bolts that are different between them, but i dont know

all the deminsions are the same

why not get the rods w/ the crank?

 

[Dr. Dyno]

Yes, there are two different casting nos. for the 258 rods. The 707 casting appeared on '71-'81 rods while the 352 casting appeared on '82-'90 rods. Physically they're both exactly the same (including the rod bolts) so there would be no problem mixing the two casting nos. in the same engine. Just make sure they're all weight matched and have the same side thickness because there are variations in production tolerances.

 

[streetpirate]

I already have the crank, and rods are $10 each at the dismantler.

is the side thickness just the width of the rod at the bearing end?

is it important enough to take a caliper with me when i go to buy them?

 

[Dr. Dyno]

Yes, take a caliper (a micrometer would be even better) and measure the width of each rod at both the big end (rod bearing) and the small end (piston pin).
Since the rods are only $10 each, I suggest you buy more than six (12 would be ideal). After you've measured them, you can weigh each one on a digital scale, select the six rods that are most closely matched for weight, and evenly polish the rod beams of the heaviest ones until they're all the same weight as the lightest one in the set.