resizing connecting rods?


This last 25% is foreign territory at this point
Founding Member
Nov 29, 1999
picking up a 306 disassembled shortblock tommorow. seller says it has 15k on it, but thats too many miles for me so as soon as i can, im going to send it off to the shop along with the stock crank and a set of forged speed-pro's to get everything lined out and balanced etc. my question being, assuming i use good hardware(ARP) am i ok to have the stock forged rods resized or should i invest in a set of eagle H beams? im not attempting to cut corners, just trying not to spend unnecessary i know the future plans for the motor have a lot to do with it and right now im just planning to build a fairly stout N/A 306and then put the juice back to it down the road. motor will see a good amount of track time and i want something i wont have to worry about breaking. Trying to build this on a reasonable budget :D
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The question is how much juice you're gonna put to it, as well as the RPM range you're shooting for. Too much punch and too much speed will break them, but you'd have to be throwing a lot.

500-550 horsepower at 6000 rpm? Stockers should do just fine. But I wouldn't push them much beyond that.
the stock rods will hold long after your stock block lets go.

that was my thinking as well.

i dont plan to spin it past 6k, and im running a 125 shot on the current motor, but i cant say for sure how much ill put to the new one.

Im just thinking that the stock block will reach its limits before the crank/rods do :shrug:

Just going to have my machine shop check everything out and hopefully wont end up costing a fortune
for a re-size, grind/polish of the crank, and a balance you will probably spend 3-400 dollars. Worth every penny IMHO too.

You could most likely throw everything together and it will run fine, but the cost to have everything balanced and in perfect order is to me cheap insurance that everything will run like a top when I get it all assembled.
basically the guy tore the 302 apart, had it worked over to a 306, ran it for 15,000 and took it apart to swap in forged pistons and turbo it (seems like a lot of people dont get past the teardown stage) and then found a 351w. So it still has everything to put it back together, and im sure it would run fine, but im not comfortable cutting corners.
$400+ is worth it to me knowing everything is fresh and functional.
I figure ill save some money by assembling it myself