i have a 406 in my car (sbc) and it threw a connecting rod, now heres my ?, a 400 sbc's rod length is 5.7 inches right? and a 305 or 350's rod length is 5.7 right? so there for i could use a 305 or 350 rod instead of buying 8 more right? i just wanted to confirm this, thank you

 

No, they are a different length. 400's use slightly shorter connecting rods (stock).

 

Stock 400's use a 5.565" rod.

 

thanks guys, i have another question, should i take and buy a used stock rod from my machine shop, or buy 8 new stage 1 rods from summit, my mods are in my sig, and im not planning on revving this motor over 5500-6000 rpm, also the rod that broke was one i got off of gables machine shop in akron, and was screwed over by them on many things, so i think that rod might have been junk since i got it, thanks again for your quick replys

 

I would buy 8 new ones. Is the crank okay? I would personally feel better knowing I had 8 new ones, or reconditioned, than 7 old, and 1 new.

 

If you are changing the rods then go to 5.7 rods it will help add some extra life to your block

 

If you change to 5.7" rods you will need new pistons.

 

ME is correct.

Remember when you replace the rods, to not skimp on the hardware. Get ARP, the insurance is well worth it.

 

i dont want to change pistons because i just bought 8 new pistons. If i bought 8 stage one rods from summit, wouldnt they come with arp studs and nuts? thanks

 

I believe that you need pistons to match the rod length on a 406...don't forget that the rotating assembly is different from any other small block...

If I were you...just get some decent stock 400 rods and have them magnafluxed/shotpeened and prepped with ARP rod bolts...use them with what you have...or spend the money to do it right...

HTH,

 

ok, i got it all apart, the cam is broke into 2, and 4 lifters are in multiple pieces, anyhow, i got another rod and the guy at the machine shop thinks the rod bolt was stretched bolt or a rod bolt came and that caused it all, and i was wondering what you guys torque your rod bolts to? i torqued mine at 45, thats what summits website said. thanks

 

45 is really too much; when I build a 400, I use 35.

Too much torque distorts the cap and makes the cap and rod dig into each other where they come together, as well as putting all sorts of strange stresses on everything.

Usually a rod bolt breaks first, that's what makes everything let go. The single most common scenario is a rod bolt that breaks right after the motor is built, sometimes wven a piece will be left laying in teh bottom of the pan; this overstresses the other one on that rod; then at some later date, sometimes MUCH later, it gives out, and what happened to you happens. Overtorquing the bolts is the usual cause.

Don't use a clicker type torque wrench when building an engine, use a beam or dial type.

 

Doesn't the torque specification depend on what type of rod bolt is being used and also the lubication applied to the threads? (Oil vs. ARP lube) ??

I researched this when I torqued down my ARP bolts on my stock prepped rods...

I don't exactly remember what I went to...but 40 ft/lb sounds about right...

 

i was stuck in the same situation about the torque specs on my scat rods......

when i had my kit balanced i had my rods pressed on there as well.. but i forgot to keep 1 box that had the torque specs... well i called scat at they said 45ftlbs......

if unsure call the rod manafacturer and see what they say.. hell they make the rod so they should know....

btw, mine were the 4340 i beams that had 3/8 arp cap screws