theinstag8r

iTrader: (3)

Has anyone had the same bad luck as me. Spun another rod bearing at 500 miles on a complete rebuild. all new internals, fully machined. The motor is back at the builders
apart but is scratching his head as to why. Says detonation was a factor but i dont think so. Car was in low octane table and had no timing and wasn't running lean. Just trying to find out about other peoples bad luck and if you ever found a cause.

68 RS Convertible

iTrader: (1)

You said spun "another rod bearing". Is it the same rod that is spinning bearings? If it is the same rod was the big end checked out after the first bearing spun, and was it resized? Just some thoughts. Did your builder provide you with the bearing clearances? If so what are they?

KCS

iTrader: (20)

Engines don't spin bearings for no reason.

We need more info so tell us the whole story, like why it spun the first time, how much work did the machinist/mechanics do, how much did you do, which bearing(s) spun, etc. Then we may be able to help you out.

theinstag8r

iTrader: (3)

#1 spun this time. I Did a head cam swap and within 100 miles the 2 in the back spun last but the motor had over 100,000 miles. i contribute them spinning the first time due to hard driven miles. The car always had good oil pressure even after the bearings failed. Pump was ported and shimmed .100. Every inch of the motor was machined on rebuild with all new everything ( stock gm crank, gm rods, diamond pistons, clevite bearings. Clearance on the rods was set at .0026. The only thing that is weird right now is the #1 exhaust port is completely clean with no carbon residue. I drove the car light for 500 miles before it was brought to the dyno. 1st pass car can 350hp up 4000 and dove after that. AFR was 14.5ish. put injectors in car pulled 400hp afr 13.5ish but still was diving after 4000. checked fuel pressure which was good but the gage was tweaking a little so i decieded to change the pump. on the way home the bearing spun before i got to the highway. I had the oil filter that was changed right before the dyno pulls. Cut it apart and found copper in it. The motor was broke before the pulls.
it was the 3rd oil change before the dyno. Compression 10.8:1 and i run 100 octane. I dont know what else to say so ask away.

Shawn @ VA Speed

iTrader: (3)

did you put in new gm rods or reuse a set of old ones?pistures of the bearing would show alot if you can get some.No 1 rod bearing shouldn't be a oil problem-it could be a clearance problem or possibly a detonation issue-if you had a bad or plugged injector on the cylinder-it could lean it out enough to do some damage,got to remember the wideband only shows an average afr.

ATwelveSec02Z28

iTrader: (17)

BINGO....

the OP mentioned there was no carbon at all in the #1 exhaust port? Sounds like that cylinder had no fuel or fire.

Id lean toward no (or too little) fuel but you mentioned changing injectors.

If there was no spark Id imagine the cylinder might still fire from heat and compression but I could be wrong... If it didnt fire at all and was getting fuel it could get into a hydrolock type condition and pound out the bearing.

theinstag8r

iTrader: (3)

rods and crank were new GM. I'll see if the spun bearing is still around and try to get pics up tomorrow.The injectors were changed after 2 or 3 pulls on the dyno to 42#'s. I could have driven the motor with a clogged injector and would have never known. I have solid mounts and true duals so i cant hear or feel anything. i am going to have to keep a closer eye on the motor when it comes back in a couple days. I never questioned something being wrong with the motor because it seemed to run good.

nkautz1

iTrader: (1)

Solid motor mounts combined with cylinder 1 not firing causing imbalance. Engine vibration originates at the crankshaft and solid mounts can't soak it up. The crank can move about 0.0015" before it makes contact with the bearing so if the vibration force is enough to overcome the oil film, like being down an cylinder , then you have a very limited amount of runtime before a bearing gets knocked loose and hitches a ride with the journal.

G Atsma

The OP hasn't been here for over 4 years, plus the thread is over 9 years old.

Ls7colorado

iTrader: (3)

Geeeez and I just read through all the posts........

LilJayV10

iTrader: (39)

Old post police on the scene.....

Your post count is getting impressive Sir.

Z28SteveA4

iTrader: (16)

I did the same damn thing lol read through it all and was so disappointed it was from years ago

G Atsma

It's a dirty thankless job, but somebody's gotta do it.... lol
I notice about 95% of the ones that do it are 1st time posters. They learn eventually....

LilJayV10

iTrader: (39)

Yeah because of a lot of people actually "USE" the search function and research a problem before posting.

Yeah they learn don't come to LS1tech and ask questions because there are ******* d-bags that bash them when they do.

Keep up the good work.

G Atsma

I would hope what I do isn't bashing. Just making sure they know how old a thread is being responded to, giving them a reason the OP won't respond.

LLLosingit

iTrader: (4)

I don't see anyone bashing people when they bring up past posts when it relates to a problem they are having and need help. But digging up old posts where the OP is long gone and adding to a dead topic get's old.

G Atsma

The first thing I do when checking out an old thread is check the poster's Public Profile. It says when they were here last. If pretty recent, they might reply to exhuming an old thread.