All spitfires having three main bearings. This means that the center main
must feed oil to both #2 and #3 rod bearing. Opening the main galley is
only half the answer. After chasing this problem longer than I like to admit
on my 1147cc race car, I came up with this crank mod in addition to opening
the main galley.
1. Main galley in block - drill one drill size larger than existing hole to
remove all rough casting burrs and smooth for better oil flow. The
restriction is actually the crank not the block.
2. Center main of Crankshaft - From #2 and #3 rod journal use #8 drill and
drill back to center main - stop just short of breaking through to main
journal surface. This requires special order (long) drill bit.
3. Center main of Crankshaft - Use #K drill to open up the main leading into
the two rod oil holes. Then spoon for oil pickup.
This has solved ALL my bottom end problems for over 15 years. This applies
to 1147 and small journal 1300 engines. I've never calculated requirements
for the 1500. I have always felt the problem with the 1500 was the weight
and stroke of the crank. But if you are seeing #2 or #3 rod failures it is
probably due to lack of oil.
I was burning bearings - not breaking rods or cranks - but then those are
modified also. Balancing the rotating mass (crank, flywheel, pressure
plate, front pulley, rods, pistons,pins, rings, and rod bolts) is as
important as improving the oil flow on a three main crank !! I use to rev
up to 10,000 rpm and finish races before SCCA allowed alternate
transmissions.
Tech tip of the day.
Ron
ReK Racing
----- Original Message -----
From: Mostrom, Paul <Mostrom.Paul@principal.com>
To: <spitfires@autox.team.net>
Sent: Monday, February 21, 2000 10:55 AM
Subject: RE: 1500 head modification questions and others (kinda long) and
getting longer
>
> Michael,
>
> Drilling out the oil gallery feeding the center main and rods #2 and #3 is
> documented in the Triumph Spitfire 1500 Competition prep manual. It is
> intended to increase the oil flow to rods #2 and #3, it does not increase
the
> oil pressure. If your bearings are loose, your oil pressure will be low,
if
> your oil pump is worn - etc. etc. etc.. Pumping more oil may postpone the
> inevitable, but so will 5w50 Castrol Syntec!
>
> ( see 1980 Ford F-100 TSV below - 4 years on rattly rod bearings &:o)> )
>
> I have run into several 1500 engines in the past few weeks that have spun,
> thrown or otherwise mangled #3 bearing/rod/block. I have two 1500 engine
> builds that I will be doing this year and I plan on drilling out the oil
> galley on each one, the rod bearings will also get special treatment.
>
> I would not do this procedure without tearing the entire engine down.
Even a
> small metal shaving left over could ruin your whole day (not to mention
the
> engine). Check out the 1500 Prep manual, read it a couple of times.
After
> reading it (and the number of bad 1500 blocks I have seen lately) I came
to
> the conclusion that the lower end of the 1500 engine is inadequate for the
> stresses put on it. I believe (flame retardant coat at the ready) that
this
> is not only a design flaw, but it also relates to the way that people have
> used and abused these cars. I know I do and I love every minute of it!
>
> I won't be going to the all out race specs contained in the manual, but I
will
> be using the parts that 'beef-up' the bottom end. I want my engines to
last
> as well as perform well (on the street and on the track).
>
> Thanks,
> Paul Mostrom
> '77 Spitfire 1500
> '80 Ford F-100 (Triumph Support Vehicle)
>
>
> 'Black holes, where God divided by zero......'
>
>
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