im under the impression that the reliable stock short block rev limit is about 6500. but im concerned with what exactly gives out first. like on the ls1s its the rod bolts. is the crank too weak? or is is the fact that they are 2 bolt main or what?

 

rod bearings i do believe. they were to sloppy or something to that affect

 

Rod bearings are the most common fasilure but it is likely caused by the rod bolts allowing some wiggle. The crank and 2 bolt mains are the least of the concerns.

 

what is the common fix for this?

 

Rebuild it, or a good Oil Pump to help..

 

+1 on that. New bearings and good rod bolts are the way to go.

 

i def hear more about spun rod bearings. most just upgrade to arp bolts. mine had a spider arm bend and spun a lifter. only found two other people that its happened too though but might be something you would want to check carefully or replace.

 

^^That's out of the ordinary..lol

 

+1, better to overbuild then underbuild IMO. My shortblock was built to handle way more stress then it will likely encounter, but that means I can take some of my worries away from the engine and worry about the tranny and rear instead.

Aftermarket rod bolts are def a suggested upgrade. The L19 ARP rod bolts are honestly overkill for most builds but if you can get them to clear then thats one less thing to worry about. They are like 1/16th" or something taller then factory rod bolts...just large enough that many people have hit water clearancing for them when using larger rods with less clearance like eagle H-beams.

 

"mine had a spider arm bend and spun a lifter" Mine did this also I replaced the spider with a new one and mixed and matched stock and ls7 lifters threw in speeddemon24'c LE2 cam in and RAN it! SORRY to get of subject

 

Yep, its more the rod bolt then the bearing, the bolt stretches, bearing spins.

 

mine ate a few connecting rod bearings

 

Putting a higher pressure spring in the stock pump seems to be a somewhat effective bandaid. Have to understand that the oilpump moves a certain volume per rpm and the higher pressure spring just delays the rpm at which the bypass valve opens and bypasses oil back to the pickup rather than sending it though the bearings. High volume pumps will just hit the rpm at which the bypass opens and sends some of the oil back to the pickup sooner.

Good to understand that oil pressure does NOT support the crank or rods either, they are basically hydroplaning. The higher pressure basically results in a little more volume making it to the bearings which may help keep the bearings and crank apart when the rod caps wiggle around from the bolt stretch.


Far as "fixing" this, sort of a slippery slope. By the time you pay a shop to press off the pistons, rebuild the rods and reinstall the pistons you will have probably close to $250 into it. Getting near the price of a Scat rod that would be a little better. Then again if buying rods why not buy more........................................

That is why a lot of guys just make due with the stock shortblock and keep it below 6500, if you spin a bearing a replacement junkyard shortblock is easily had for $500 or less. Keep in mind the b-body shortblock is idential and likely less abused so unless you want the extra aluminum heads it is a waste to pay a premium for an aluminum head motor, even then watch that the price difference is less than you could buy core heads here for.

IMO people should not be doing these "budget" engine builds, just stick with the stock shortblock till you can afford to do a GOOD shortblock. Too big a hit to the budget when a $200 POS cast crank breaks because it was WEAKER than stock. I would not build a motor with anything less than Compstar/Mahle stuff. Just see too many guys have trouble with the cheaper stuff. Yes some have good results, but not a gamble I could afford to lose.

 

+1 - build it right the first time.

Racing is expensive enough without having to go back and fix mistakes down the road.