On Thu, 29 Jul 2004 13:42:52 -0500
"Barr, Scott" <sbarr@mccarty-law.com>
Wrote: Subject: ARP Bolt Failure?
I pass along the following for whatever interest it may generate. A couple
of weekends ago at Road America, my new Spitfire motor blew up in a pretty
impre$$ive manner. My first thought was that a rod bolt on #2 had broken --
the
#2 rod cap was seriously damaged and one of the bolt holes in the cap is now
D-shaped -- clearly, the ARP rod-bolt was not in its hole when that damage
occurred. But, these being ARP rod-bolts, I concluded that there must be some
other explanation -- that it had been starved of oil or something.
On disassembly, however, none of the other bearings show any real wear. My
dad (with 40-some years of experience in the engine building business) took a
look at the mess and concluded an ARP rod bolt broke. He showed the mess to a
Caterpillar Certified Failure Analysis Instructor, who concluded an ARP rod
bolt broke. See below for that discussion.
Anyone else have experience of ARP rod bolts failing?
Scott
Hi Scott,
An interesting story.
What puzzles me though is your choice of Spitfire 1500 engine for racing?
According to my recollection, the 1493cc engine has heavier Crankshaft,
heavier (TR6) Con-Rods, heavier flywheel, a longer stroke and wider (TR6)
bearings
with increased drag, none of which lend themeselves to high RPM.
In this particular case, bigger is not always best.
I would recommend that for your replacement engine, you seek out a 1967-1969
Spitfire Mk.3 1296cc engine, (FE engine prefix in the USA?), perhaps bored out
by 40 thou to accept GT6+ pistons, (this raises the c/r to 10:1).
A decent camshaft from say Ted Schumacher, (running in cam bearings), an
alloy flywheel from perhaps Fidanza, a tuftrid-hardened crankshaft, plus duplex
timing gear, a free flowing exhaust and a fresh set of ARP bolts etc would
produce an engine of around 100 bhp+ at 6,000 rpm, with much more relaibility
and
an eagerness to rev.
MSD ignition stuff is always useful.
In Short, use all the strongest bits, build it very carefully, get the (cold)
air in and out efficiently, lots of (cool) gas, and good strong sparks and
you will have it sorted.
Best Regards and Good Luck
Leon
(been there, done it)
ps. just bought a set of Aviation grade X-rated bolts from Coastal
Fabrications for my Vitesse Driveshaft/Propshaft. (as recommended by Chris
Kantiarjiev
in SF). In the interest of increased reliability. They certainly look to be of
very high quality.
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