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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