Yes you have the seq uence correct, but, even grade eight bolts are not
HARD enough for really high torques (my belief and experience) I used bolts
were not just strong but HARD. That means they do not stretch. Usually grade
5-8 are stronger but thius just means they won't break as easily not that
they don't tend to stretch. I used a cheap skate bolt thaat wes made for the
hold down plates on a milling machinme table. I unfortunatly don't remembe
the number or anything but as I rfmember a box of them was dead cheap, like
about 15¢ each. That would make them abouyt 40¢ in todays markets. Generally
you do need to take a little material off each face of the cap and the rod
so that the re-sizing of the big end will take off a small abount of
material completly around the big end. Clear as mud???
----- Original Message -----
From: Barr, Scott <sbarr@mccarty-law.com>
To: 'R. Kastner' <kaskas@earthlink.net>
Cc: <fot@autox.team.net>
Sent: Thursday, March 23, 2000 6:14 AM
Subject: RE: preventing loose rod bolts (was a couple questions)
> Ok, to summarize a part of this discussion:
>
> 1. If I'm replacing the stock rod bolts with higher grade bolts (ARP
> in my case), then I need to torque those bolts to a higher torque spec
> or risk having them come loose, and
>
> 2. if I had the rods machined on the Tobin-Arp machine with the stock
> bolts in place and torqued to the stock torque, then I need to send them
> back to be Tobin-Arped again (with the new ARP bolts in place, torqued
> to the higher setting) or risk having the big end out of round?
>
> Is this a correct summary?
>
> Scott
>
>
> > -----Original Message-----
> > From: R. Kastner [SMTP:kaskas@earthlink.net]
> > Sent: Wednesday, March 22, 2000 9:17 AM
> > To: Henry Frye
> > Cc: fot@autox.team.net
> > Subject: Re: preventing loose rod bolts and post rebuild break-in
> > of engine
> >
> > That's really very cool that you have a machinest that is helpful. I
> > hope
> > you remember to have the big end resized after you increase the torque
> > cause
> > the big end will definatly be out of round.
> >
> > ----- Original Message -----
> > From: Henry Frye <thefryes@iconn.net>
> > To: R. Kastner <kaskas@earthlink.net>
> > Cc: <fot@autox.team.net>
> > Sent: Wednesday, March 22, 2000 5:13 AM
> > Subject: Re: A couple questions
> >
> >
> > > Kas,
> > >
> > > Thanks for the great information. My machinist called Carillo, the
> > rod
> > > bolts I found in this engine are the best Carillo makes, their
> > torque
> > chart
> > > says the bolt can 100 ft lbs of torque. We were a bit leary of the
> > stock
> > > rod taking that kind of torque, so the shop tested the bolt in the
> > rod. At
> > > 80 there was no stretch at all. At 90, they measured .006 stretch,
> > so I am
> > > going to torque them at 90 ft lbs. The machinist gave me a packet of
> > > special grease to use on the threads, as a bolt that size under that
> > much
> > > torque will not torque up properly due to the friction on the
> > threads
> > using
> > > regular oil.
> > >
> > > No wonder one of these bolts was loose when I tore down the engine.
> > There
> > > is no way the other 7 bolts that were still under torque were even
> > close
> > to
> > > 90 ft lbs.
> > >
> > >
> > > At 09:22 AM 3/21/00 -0800, R. Kastner wrote:
> > > >I have had a lot of experience with loose con rod bolts in the
> > early days
> > > >of Triumph engine modification. You were just a very short step
> > from
> > having
> > > >that rod out the side of the block. The fretting you see on the
> > surfaces
> > of
> > > >the rod are from the cap MOVING around due to the clamping not
> > being high
> > > >enough. I went to larger ( in your case Carillo) rod bolts that
> > were
> > very
> > > >hard and therefore did not stretch, then increasing the torque to
> > 60
> > pounds
> > > >instead of 45. When I did this I first took a small amount off each
> > side
> > of
> > > >the rod surfaces, then drilled out and tapped for the larger bolt,
> > then
> > > >tightened to the new torque value, then had the rod bored to the
> > stock
> > > >diameter to make it round again. When after this everything stayed
> > togeather
> > > >and never had another loose bolt or block ruined becuase of rod cap
> > comming
> > > >loose.
>
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