Car started slowing down and then at a test night recently we broke a valve spring (no other damage), so after 200+ runs we knew it was time for a freshen...

Rod bearings on #1 #2 #3 and #5 were trashed...down to the copper in many places and had been hot enough to color the rod caps and the crank journals that lovely shade of blue/black/brown.

Here's the odd part: #4 #6 #7 #8 rod bearings looked very good for the amount of time we had on the thing, actually looking almost new!

Bearing clearance was all set at .0028, done by a VERY competent machine shop (and re-checked twice when I assembled it, and NOT with plastic gauge...lol!) and it ran good enough go a best of 10.14 @ 128. Looking back at the log books, at one point last year we made 68 straight laps between 10.22 and 10.28, so for a long time she was very healthy.

We did run a high volume pump, and with Valvoline race oil 20/50 it would show oil pressure well past 100# on cold start up and 80# warm in gear. Driver was telling me the gauge was in excess off 100# through the lights. After dwelling on this for quite some time (maybe too long?) we changed to a lighter oil (10/30) and that did knock some pressure off, but we were still over 90# cold and nearly 100# at the stripe.

I'm wondering if the excess pressure was the cause with those rod journals not "seeing" enough oil, or something else. If so, why only those rods I mentioned?

OR, was there oiling systems mods that I should have considered? I ask that because when I tore down the 300+ run 340 that was in the car prior, Rod bearings #1 #2 and #3 had MUCH more wear than all of the others.

Discuss...

Doug...according to all old reference material I have, you must
do the oiling mod to slow the oil delivery down the left side oil
galley by plugging it at the front of the block and using a Cross
over pipe from the rear of the left galley by the passage that
feeds up to the rockers to the right side galley by the front passage
to the right side rockers. This mod slows the oil delivery down
the left galley, increasing the pressure to the mains and prevents
the bearing starvation symptoms you have described.

I have a beautiful diagram of the mod I described along
with the relevant text, if you pm me your email address
I'd be happy to copy it from an old book I got back in the
mid seventies called the smallblock Mopar hand book.
Excellent reference guide for the time it was published.

By plugging the front of the left oil galley, you slow the oil flow
down increasing the pressure to all the mains..except no. 1
which is now fed through the crossover pipe to the rightside
galley. Believe me..this works and is reliable to high engine
speed.

What do your wrist pins look like. Especially on the bad rods? Are they tight? Discolored or even bent?

Wrist pins are all free. The rest of the motor looks real good.

Dart man is that pic taken from the front of the motor??

Unless you are pushrod oiling or running a juice lifter you can just block the oil to the left side lifter galley at the #1 main.

Sort of like that Dartman..it looks backwards
to me from the view of your shot, but I
Suppose the net result would be the same.
This mod maintains oil supply as designed
to both sides tappet bores, but reverse feeds
the #1 main journal from the left side galley
supplied by the crossover tube.

Here is another good oil mod tutorial from Herb Mccandless. https://board.moparts.org/ubbthreads/show...ge=9#Post522730

You should buy the drill bits from good tool supply --I forget now but I think the point angle is different and the flutes are like 120 degrees??There is a trick to the bit so it will do that specific job right. I have some of the bits and just can't remember what Herb told me before I bought them way years ago but that needs to be looked into.
The other thing Herb figured out was that Melling drilled the hole for the relief valve to shallow by .100 so it acted the same as shimming the thing up thus the monster pressure--use a std volume on SB and you never have issues. I had an original S&M 10-12 qt off one of the small block cars and it used a std volume housing with Milodon extension and longer rotors ( I am guessing No longer made) we always use std volume on SB's to avoid that plus 100 lb deal

Here is a pic of the crossover tube.

BTW.. This is a solid roller cammed block
Notice no bushings in tappet bores so this
will work with any type cam / lifter combo.

One of the things I find really interesting about this modification is that I've built literally 100's of small block stroker combo's over the years and none have this mod done to them. Noteworthy is that none of them exhibit unusual wear on the bearings, nor do they have unusually high oil pressure with a high volume pump. Of those engines, most see no more than 7800 rpm and many likely see only 72-7400 rpm at the stripe.
I believe that mod may be more beneficial to the higher rpm combo's that may run in the 8000+ rpm range. I wouldn't tell anybody not to do it, but I do question if not doing that mod is the real problem with the OP's engine.

True that.. No telling if not having this done
was the cause of the issues that developed
in that engine. Just the description of the
extreme oil pressure made me think the
mod might help. Likely the clearances were
tight and .003" might have helped with that
super high pressure too. The oil doesn't
want to make the turns down into the mains
under that high of pressure and this mod
is designed to help that issue.

Indeed thats true, but with the modern profiles introduced for street/strip use with hydraulic rollers..this mod can be very beneficial. Not everyone wants or needs solid roller cams, or solid lifter setups. And, even if they do, this mod will work for them. So, it looks like a good idea for anyone not contemplating full competition setups, but still requiring dependable street/strip performance for the long term between teardowns and rebuilds.BTW those aren't 90 degree
elbows for the crossover tube. More like 60*...