bufmatmuslepants

iTrader: (3)

Who has actually done it? I'm talking rod bolts, something snapping, etc, who has spun it too high, what was the failure, how long, what rpm? Excluding rockers, just bottom end.

joelster

I spun a bearing in my original 350 shortblock. It still ran, just had near zero oil pressure and would stall at an idle. I only took it up to maybe 6300rpm. After I let off and coasted to a stop, the engine just died. It fired right back up and I noticed the oil pressure was around 5lbs at 1200rpm.

Catmaigne

iTrader: (6)

About 12k hard miles on the street with a cc503 and 2 track days was all it took. Stock shortblock had 99k on it when it went. Never overheated it, never missed a shift. Oil pressure wasn't even that bad after it went, only lost about 10 psi across the board. Sounded like a lifter tap at first but then the engine started stumbling at low rpm. Tore it down and found a trashed rod bearing, one on its way out, and a main that was so bad it burnt and grooved the crank journal.

96capricemgr

iTrader: (1)

Ate a rod bearing on one short block that saw 6800 a bunch of times BUT had also had some fueling issues that might have contributed by way of detonation. Next motor still alive and has raved higher, true junkyard stuff.

IMO once going over say 6500rpm you just need to accept how far outside the design spec you are and that you are risking damage. A junkyard long block cost about as much as good pistons much less the rest of a build so many of us throw the dice.

94LTZ

iTrader: (5)

I spun to 6800 RPM with about 15-20 bottles on a 125 shot with a stalled auto, never had a issue until I had tranny issue (tune related) and twisted/bent the crank on a over rev.

Puck

iTrader: (17)

It wasn't a catastrophic failure, but too many trips to 6300rpm on my stock shortblock build wore down the bearings enough to cause a low hot idle oil pressure. Ran a H/C build as a daily for 2 years, and the build was installed on a motor with 145k on the clock LOL. Motor has 160k now and is still strong and doesn't make any noises yet, but it definitely caused some damage.

This was over the course of 2 years daily driving and many trips to the track, and I have no idea what kind of maintenance the car was given before I owned it, so of course YMMV.

Mine lasted similar miles, about 15k, but had a lot of track days on it...and even on the street I wasn't too nice to it .

fex77k

iTrader: (2)

Put a msd dig 6 box on my motor when it was nearly stock had the hard limit at 5800, snapped a wrist pin but didn't kill the block. Spun the next motor to 6800 but it had the clevite H bearings.

bufmatmuslepants

iTrader: (3)

Lets keep them coming, I tried searching for failures and couldn't really find a spot they are documented, a lot of people ask what the safe rpm limit is, I wanted to try to get a thread to refer them to.

Fex77k, I'm debating putting your 230/240 in my 110k motor while I'm changing the timing cover seals and seeing how long it will last until I rebuild the other motor.

To add to this I had a 130k mile shortblock develop a knock after 30k miles of driving with the oil pickup tube fallen off the pump laying in the pan, oil pressure dropped to 0 every time I hit the brakes hard and oil sloshed to the front of the pan, starving the pump. Shifts were at 6000, no track passes.

joelster

My next 350 was a stock rebuild, never bored, never re-ringed, just new bearings, and cleaned. It is sitting on an engine stand waiting for a new home. It has been to 7k hundreds of times. I ran that motor for years and went 11.11 at 121.65

Dirty_Bird

Spun my stock bottom end to 6500 or so for 2 years with no problems. Had arp rod and main bolts though

ahritchie

iTrader: (1)

I had a catastrophic failure when a stock rod bolt let go after a missed shift and being spun to 6500-6600 RPM when it was cam only, it was freshly rebuilt recently before that happened at around 140K

93M6Formula

I spin my 119K mile motor to 6400 with a CC503. I only have 30 passes and probably 1000 miles of this abuse though. Runs great so far with no wierd noises. I do notice my oil pressure is a little lower at hot idle than it was with the stock cam. I assume warn cam bearings possibly. I've owned the car since 87K miles and it's been some hard high RPM miles with well over 200 track passes and WOT pulls and street races. I don't expect it to last forever, i'm already building the new motor on the side for when the time comes. It's been a great reliable car considering how i've treated it lol.

fex77k

iTrader: (2)

When I started to run the progressive with a the small jets (100-125ish) I shifted at 6500, just as fast and less heat at the end of the run. I also started to carry the wheels off the line so it was making a lot more power on the bottom end. 5k stall on the transbrake helps too.

moehorsepower

iTrader: (3)

not built like the old daze, I know we are talking about our LT's but why back when, I would spin the old Z28 302 to 8000 rpms! Yes finally a rod decided to peak out the side of the block, but that motor took hell...

JoeliusZ28

iTrader: (2)

110k on mine it sees 6300 shifts all the time. (Cammed it at 92k). Back when i put the cam package together i noticed a lot of bottom end failures seemed to be rod bearings. So i changed to the gm white oil pump spring for additional oil pressure. Not sure if its saving anything but i know it isnt hurting. I also got rid of the BS oil "cooler" and started using a taller oil filter for more flow/capacity. Engine has really good oil pressure, cruise RPM and up it reads at least 50 psi

myltwon

iTrader: (1)

I had a rod bolt stretch around 130-140k, but that was after 50-60k miles of regular abuse in a 180 shot car (with basically a stock tune) and then a CC503 setup.

Casey96SS

Hey Joel. Just wondering if you pulled the motor when you put your white spring in? I am considering doing the same thing. Sounds like a PITA to do it with the motor in the car.

JoeliusZ28

iTrader: (2)

I did it in the car. But trust me, i could have pulled the motor in the same time and invested 1/4 of the curse words.

BOLO

iTrader: (40)

I've ran my stock bottom end LT1 to 7000+ rpms many,many times. The motor finally blew, but it was because of a weak pushrod and it took a piston with it. Opened her up, and the rods, rod bolts, bearings, and crank were still good to go. I had a FREAK bottom end is all I can say.

bowtienut

iTrader: (1)

Well, I've been rolling those dice for 6 years with stock bottom end parts, and I rolled them for the last time last week at ISSCA Nationals. Something in the bottom end let go crossing the traps with a 2nd round win at the strip. BUT........not before lots of laps around NCM track and taking 1st in our roadracing competition
Hundreds of dragstrip passes spinning to 7000+ are nothing compared to hours spent in the 6000-7000 rpm range in these past 2 years of roadracing it. I shift ~6800 rpm on the roadcourses, but still hit 7000 on some tracks to avoid a shift just before a braking zone.
I'm calling it a year. Too many other things to do while the weather's good. I'll do the autopsy later and report back.
I've been prepared for this cheap little motor to give it up for a quite a while, especially since I put it on the roadcourses. Been carrying those chains and come-a-long in the truck for the past 3 years