i have a engine built for my evo 9 it has AMS spec oliverrods, AMS spec Ross

Racing Pistons. ok here it the problem when we put together the engine

we sent everything to the machine shop to have everything checked out to

spec. we get it back from the machine shop and put to motor together with brand

new everything from the bottom up acl main bearings, clevite rod bearings, new oil

pump, gaskets, BSR the car even has a new head on it. The motor spins #2 rod

bearing the other day and when i pull the oil pan off the rod looks to be a little

miscolored burnt on the side closest to the #1 cly this also happened on #4 Cly

but the bearing did not spin on that particular cyl. we checked the rod clearence

with a feeler guage and could only fit .007 between the rod and the inside of the

crank journal on the #2 cly and #3 and #4 but on cyl #1 we could only fit .006

between the rod and the journal. i called up oliver and tim said i should have .012

side clearance and something is wrong. the motor only had a little over 4300 miles

on it and it had a very nice breakin of like 1800 miles with 10-40 and then

i changed oil after miles 50-150-300-500-1000-1500-1800. but i noticed after i got

it tuned that the oil light would flicker and the rpms would drop a little idleing after

the car is warm. i am really scratching my head for this one i do not know what

went wrong is it the little flickering light that spun my bearing ? or do i not have

enough clearance between my rods and journal edge ?. oh yeah my crank was

re polished for this build also everything was on a fresh surface. and when the

bearing spun there was no damage done visually to the crank but it is still getting

re polished after this mishap. i appreciate all the help in advance i hope someone

has the answerers i am looking for.

Jeff

Precision Psi

 

difficult to diagnose failure with out actually seeing parts. can tell you .006 side clearance would not cause bearing to spin.

 

tim at oliver said i need to have .012 that is why i was asking about the side clearance. and the rod heated up on the 1 side of it you can see where the heat started to change the colors.

 

A friend of mine had a very similar occurrence, it turned out that the machine shop polished off the nitrile coating on the crank. Don't know if that is possible for you but something to consider...

 

Did you plasti-gauge the bearing clearances?

Sounds like it could be either too tight to too loose if you spun a bearing this quickly. My guess its loose dropping oil pressure. I don't think you're supposed to touch the crank on these cars due to the nitride treatment.

I'm sure you could just call up AMS and ask them for advice too you know. Its their parts i'm sure they will recommend you the best possible way to put it back together.

 

Mitsubishi cranks are not nitrided. And even if they were nitride penetrates at least .002 deep but usually much deeper. When I treat cranks they ask me how deep I want the treatment, .004, .008, or .016. This is done by increasing time of treatment. 4 hours, 12 hours, or 24 hour.

factory stock side clearance is .004
.006-.008 is good for high performance.
.012 would just allow the rod to move back and forth more than it needs to.
rod to bearing clearance is .002 so that is all the side clearance that is needed to not impede oil run off from bearing. I have seen engines built that tight witout issues.

 

Im with 94awdcoupe. you miss the first and most important step ,plastigauge.also check your oil pickup screen have the gasket and check the balance shaft bearings.also did Clevite has the extra clearance .001 bearings like ACL and Cosworth?

 

Ah didn't know that the evo cranks were not nitrided. I believe the 2g cranks were though and that's probably what sparked the idea the evo crank was as well.

 

I just got a crank back from being nitrided becuase of all the "mystery" surrounding these "unservicable" cranks.

I am having to rebuild again because I had flipped one of my rod caps causing a bearing to spin. It's easy to do, there are NO markings on manley rods. This time I've engraved a very small mark on one side before taking them apart the first time.

I also had a bad BCS which caused detonation and the piston skirts to scuff up. I didn't know the BCS was bad (Stock everything except an AMS stroker kit and a wideband) until i installed a boost gauge post-rebuild and it was spiking off the 30 psi gauge.

It's VERY easy to miss something putting an engine together. I've done a couple and this is the first major failure on my part. I've decided to go with off-the-shelf parts this time so that if something else happens i don't have to order 4 more of everything.

 

Can you not reference which way the cap should go on the rod by matching up the tangs for the rod bearings?

 

You can. I spent a lot of time checking and double checking. The problem is that aparently the last time i checked i flipped it. Super easy to do. I remember thinking that it didn't look right. There was a hairs worth of mis-alignment visable on the rod between the cap and the main part of the rod. i remember taking the cap off to check, thinking something and putting the cap back on. It ended up being wrong when i pulled it apart.

The moral i got was that having to pull the caps to check leads to disaster. It's better to have markings on the outside. I checked probably 5 times because i wanted to be SURE. I did the build over several days so i could check everything. If i had markings on the outside (not the tangs) i could have just looked at them and felt good about it.