capri debris

What have you guys who switched toARP main studsand rodbolts do? Do you have the rod bores honed out and crank bores line honed? The theory is, the new ARP fasteners position the rod/main caps slightly off and affect the bore roundness... so ARP recommends having all the bores honed to "true" them up again. This has to be done with the caps torqued in place. I thought I was ready to build my engine, but now I'm sendingstuff back off to the machine shop for another $350 worth of work. Has anyone just put the ARP studs/bolts in and NOT honed the bores? And how has it worked for you?

mjr46

It's a good idea no matter what your doing to be safe rather than sorry... is 350.00 worth possibly taking a chance on a expensive build??? not really, I've tried it all ways and in the end it bites me, so this build I'm doing now, although, it'll be more expensive than I want, it'll hopefully last longer than the other engines I cut corners on[:@]

cleanfitty

Well, I was reading about ARP stuff and from what I got from it is that I guess the rods and main caps are supposed to be machined with the bolts in them torqued to spec and then it is crucial that they then get reinstalled back in the engine with the same torque. (I guess they suggest that you coordinate that with the machinist)
I always get wierd vibes about that bolt stretch stuff... like measure the stretch of the bolt rather than torquing... andif they get stretched then dissasembled to get put back in the engine, are they still good, will they unstretch??? And the tighten and loosen 5 times to get a more accurate final torque... couldn't that ruin a head gasket???

Also, it seems the only time there would be an issue with caps not lining up after ARP bolts would be with the wave loc ones. I could be wrong though...
I suppose you can ask your machinist and pick his brain on this as well..

By the way, fantastic job on your teardown and rebuild... And it sucks to have small (but costly) setbacks like this additional machine work...

capri debris

Yea, I consulted with my machinist about honing and he said it's a MUST when changing the studs and bolts. He wasn't just trying to get more work, because he's pretty booked up as it is and really didn't want to do it for me, but I convinced him to fit me in. I'm concerned about the whole bolt stretch thing too... I mean, when he torques the rod bolts and stretches them to do the honing in the rod bore, how can it be good to loosen them and then re-stretch them when I install them in the motor? Also, I'm going to plastigauge everything and that means I'll be putting it together and taking it apart severaltimes... so will that fatigue the bolts and studs too? I think I need to call the ARP people and find out what the do's and dont's are with these fasteners. I'm finding out there is alot more to ARP fasteners than I first thought!

my77stang

yup. i just put the best 5/16 bolts ARP makes in my 289 rods. they chamfer the top of the bolt hole cause there is a radius between the head and shank of the bolt which the stock bolts dont have (a major weak point) and once they are fitted to the rods they need to be resized to ensure the big end of the rods are round and true (you should always recondition rods when rebuilding a motor anyways)

i'll get some pics up for ya's

cleanfitty

Exactly!!!

dimebag

yea, get it machined... the thing is... and ask your machinest, hell explain it too... when you tq 2 parts together, say rod and cap... with bolts, all the pulling force is in the rod, and the cap is pulled down... if they were perfect circles before tqing them down, they will not be now. thats why their bored assembled and torqued. when you switch to studs not bolts, the pressure compleetly changes its not longer pulling the block to the main cap, but now its pushin the cap down to the block... again, changing how that circle would be that they made when it was bolted down... thats why it needs remachined.... i hope that made sense

as for the studs and all that bolt stretch ****... so long as you dont torque to yield a bolt, you can reuse it... just tqing them used about 80% of their stretch, which will go back to normal, but when torqued and angled(tq to yield) the bolt is now at 100% stretch, and wont go fully back