: Had to take the engine out again, #6 rod let
: go! Any good suggestions on cause and
: effect? Here's what is in the engine (bottom
: end) now: 3 core hole block 0.065" over
: 1291 Silvolite pistons cut 0.130 off the top
: for about 10.5:1 comp. ratio using 35cc head
: Std crank with cross drilled mains, F-M
: bearings.
: 198 rods using F-M bearings. Balanced bottom
: end.
: Mellings oil pump w/std. spring
: Detailed block, over drilled oil passages,
: risers in lifter galley, fully deburred and
: cleaned.
: Stock pan and pickup with windage tray. Using 6
: quarts 10-30 with 51515 Wix filter. Riser
: pipes in galley and bigger filter hold about
: 3/4 quart up in engine.
: Partial groove on last cam bearing journal for
: more oil to topend. Grooved rocker shaft
: under each rocker.
:
: We think that the piston problem from before
: may have bent or kinked the #6 rod and we
: did not see it when the engine was
: reassembled. All rod bearings have some edge
: loading marks on them, and the #4 main
: smeared the babbit but did not cause any
: damage to the crank. Looks like a
: 0.020" cut on the rods will fix the
: crank, and we have another set of 198 rods
: for a rebuild. Oil pressure runs at 50psi
: all the time, and we really don't know what
: could have happened.
:
: Car ran 15.7 @ 87 in 90° heat the first time at
: the track with a low 2.3 60 foot time,
: shifting 1-2 with the trans and 2-3 manual
: shift. Need tach or lite because we think
: that the trans is shifting at only 4000-4500
: rpm, and the cam wants at least 5200-5500.
: Headed for mid 14 sec at 92-94 in a street
: driven 4 dr car.

: This engine has bad karma. (I have a few like
: that, I'm working to get one of these back
: together now, hopefully I've scared-out the
: demons)
:
: As for your rod bearing failure, usually one of
: two things, clearances or oiling.
:
: Check everything twice, measure everthing
: carefully, rod bearings should have .001 to
: .002 clearance, mains .002 to .003 for what
: you are building.
: Check the rod journal to be sure it is sized
: correctly all the way accross, right up to
: the edge undercut.
: DD

: Thanks for the reply.
: Talked to the machine shop today when I dropped
: off the parts. They questioned the use of
: cross drilling the crank, as all of the new
: race motors they build are not cross drilled
: or even have full grooved bearings. These
: are of course Chevy & small Ford motors,
: and the mains are so narrow a full grooved
: bearing affects the total surface available
: for the mains to ride on more than a 6.
:
: Another thing that was discussed was the oiling
: system, which in a 6 is really pretty good
: compared to some of the Ford and GM engines.
: Is the long rotor std. pressure pump enough?
: Was diverting too much to the top of the
: motor the cause of #6 rod going bad? This
: engine still had 40 psi pressure with a rod
: bearing almost completely gone. Would an
: accumulator by Moroso help? Really don't
: think that lack of oil is the problem, just
: oil clearance.
:
: Looking at the rest of the rod bearings and the
: mains, we decided to use a new set of 198
: rods with ARP 142-6002 bolts all correctly
: resized and fitted to the crank @
: 0.0015"±, regrind the crank to
: 0.010" on the mains and 0.020" on
: the rods and fitted to the main bores @
: 0.0025"±.
: Any further thoughts? Thanks again.