Hmmm,
I must admit that I've never seen nor even heard of a
Spitfire con-rod bolt failing, at least not as the
primary failure.
These are 3/8-24 x 1-1/2 bolts.
My FSM lists two bolt types, phosphated at 46 ft-lb,
and color dyed at 45 ft-lb.
According to the Carrillo connecting rod installation
guide, 3/8 bolts should be torqued to between 45-65
ft-lb, depending on the bolt material.
The torque wrench method is subject to variations due
to thread finish, thread lubrication, the finish of
the underside of the bolt head and of it's mating
surface, etc.
The preferred method is to measure the amount that the
bolt stretches under load, about .005-007" for ours.
This preloads the bolt to approx. 80% of the tensile
yield value.
Here's a couple of URL's, for the curious:
www.carrilloind.com/install.html
www.eaa1000.av.org/technicl/rodbolts/rodbolts.htm
Note that 1500 big journal rods have an access hole
neatly drilled into the cheek of the rod at the root
of the blind bolt hole, perfect for measuring rod bolt
stretch.
I was rather surprised at the weight of the Spit 1500
pieces, 750 g for the rod (with bolts), and 475 g for
the piston (with rings and pin). That's awfully heavy,
lot's of V-8's are lighter.
Like I said, never seen one fail .... but maybe weak
stretched bolts allow the cap to seperate and flex
under high loads, contributing to early bearing
failure.
Carter
--- PorscheRcr@aol.com wrote:
> In a message dated 07/09/2001 12:56:55 PM Pacific
> Daylight Time,
> jjcon2@yahoo.com writes:
>
> << I wouldn't think it would be an issue on a con
> rod. >>
>
> Not an issue? The head is stationary, the big end
> bolts hold several hundred
> grams of piston/rod mass from going through the
> head. Seems kind of
> important to me :)
> Bill J
> '68 GT8
Get personalized email addresses from Yahoo! Mail
http://personal.mail.yahoo.com/
/// spitfires@autox.team.net mailing list
/// To unsubscribe send a plain text message to majordomo@autox.team.net
/// with nothing in it but
///
/// unsubscribe spitfires
///
|