Michael D. Porter wrote:
>
> paul lacroix wrote:
> >
> > Hello list,
> >
> > I've been following with much concern, the discussion about which
> > REPLACEMENT rod bolts to use during a TR6 engine rebuild. I say concern,
> > because I've just completed buttoning up the bottom end of my first ever
> > engine rebuild, and I simply re-used the original rod bolts after cleaning
> > them and applying some locktite thread sealer. I torqued them down to spec
> > without incident and never considered for a moment using NEW fasteners.
> > Have I missed something important here??? Could someone please enlighten
> > me.
>
I have followed the thread on the replacement of rod bolts and thought I
would make the following comments.
I have rebuilt a lot of engines over the years and never believed in
replacing rod bolts until I was the victim of spending a lot of money on
replacing one of my twin chrysler engines in a high performance boat due
to a broken rod bolt. I have also had the same thing happen due to a
piston cracking at the wrist pin journal (the other engine - makes extra
breathing hole in side of block).
I still don't believe in replacing them in engines operated in a sensible
manner. I have never seen stretch bolts used on the mains or rods so
they don't need to be re torqued. There may be some of the new high tech
engines today that use them but I haven't heard of any. Head bolts are a
different story on the newer engines anyway. One time use for them.
One thing that hasen't been discussed much is the rods and the
distortion they endure. When doing a complete rebuild I ALWAYS send the
rods out and have them resized on the big ends and on the piston end
install new bushings and fit them to the new replacement piston wrist
pins. The rods will stretch and become egg shaped due the force exerted
on them by the crank. Just checking the clearance is ok a lot of times
but for a good rebuild the extra cost is worth it.
There has also been a lot of talk about replacing original pistons with
oversized ones and unknown source or from another engine. Remember the
engine is balanced to the original pistons rods and bolts. If pistons
are replaced it would be a good idea to weigh a new rod/piston and bolt
set against the originals. I have seen several replacement pistons that
were suposedly of equal weight but wern't and required re balancing the
engine. A lot of them have the weight stamped on the top of the piston.
I purchased a set of 86/87mm pistons & liners back in 62 (so long ago I
can't remember size) for a 60 TR3 that were supposedly a exact match.
When Crower in San Diego checked them they were off quite a bit. I was
already going to balance the engine so it didn't matter. By the way he
sure did a good re grind on the cam for it. I used to wipe out Jag
XK 120/140's and 4 banger Porshes at Pamona drag strip back then.
Joe Worsley
80 TR8 DHC
Tupelo, MS
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