Well, disaster struck while disassembling my LS1 engine from my 01 Supercharged Corvette, I discovered a crack in the block where a head bolt mounts to it. My car has ported 243 heads and ARP head bolts. I have no clue how long the crack was there given it didn't leak coolant. I can speculate it occurred from too much power, the shop who had installed the heads over torquing that bolt, not cleaning the bolt hole out, etc.

It doesn't matter at this point. I have called around and been told by 5 engine shops I would be rolling the dice if I could find a shop willing to weld the crack and none of the shops were willing to do the weld.

I contacted a shop who specializes in LSX builds and they told me they believe they could find me a bare, clean, LM4, LM7. L33 or comparable block for 2-400$. My rotating assembly from my LS1 was clean, I would be having a machine shop going over it and the block assuming I can find one. Question is would my rotating assembly drop right in with some machining? Would any of those blocks drop into my car and allow me to bolt up all accessories including the supercharger? Any fabrication needed I should be aware of? Thanks guys.

 

Pics of the carnage on my LS1, any guesses as to whether it will sell on craigslist for a couple hundred bucks?



Picture of the crack from the bottom of the block...



Picture of the crack from the top of the block...

 

NO, your rotating assembly will not drop right in. The LS1 (5.7L) you had has a bore diameter of 3.898". The LM4, LM7 and L33 engines (5.3L) are small bore, 3.78".

Your pistons no fit.

You'll need to find a LS1 or LS6 block.

 

These engines are starting to get old and "good" ones may be hard to find. They can still be had new from GM, part number 12561166 for an LS6 block. It can be had for about a grand.

You'll sleep better not worrying about some used block with an unknown history.

 

Thanks for the heads up for some reason I thought they were the same bore, it might be most cost effective to go with a new LS1, found summit racing offering a brand new one for 1100 shipped. Will the rotating assembly not fit strictly because of the bore size on the cylinder or are there differences in the fitment for the crank as well?

I inquired about a cast iron LM7 iron block for 200$ on craigslist. I just read up that the max bore size on the LM7 block is 3.910. If I could pick up the block for 200$ get it bored to size I should still come out fairly far ahead versus the LS1. I would be incurring the 75lb penalty but would have a stronger block. Thoughts on this approach?

 

I have a nice lm7 block that has been cabinet blasted and looks like new. good shape std bore will need machine work. id trade for your aluminum block. if you are less than a few hours away. pm me if ur interested, im n 43440 nw oh

 

I wish you were nearby, I'm in the Denver-Metro area in CO.

 

Tommy, check you PM's.

While the iron block is strong and you can usually bore it to LS1 specs, it's weight adds what would be like adding two full sized batteries to the nose of your car.

Unless you're boosting and hitting +800 HP, the aluminum block is all the strength you'll need. And personally, I can't see a Corvette with a heavy iron block in it.

 

Thanks Paul, I just sent you a reply. For more context, I was making 651whp on my tune spraying meth after 3000 rpm running 10psi probably had me in the neighborhood of 725-750hp corrected. My tune was fine and the engine was handling the power great, I'm at almost 6000ft above sea level, so while my corrected numbers were 651 I was making 550ish uncorrected to the wheels.

 

woof that's some good numbers! Good thing you don't roam around my streets!

 

I have an ls1 block from my 00 SS but I'm in Michigan.

 

You sure an iron block is only 75 lbs heavier?
https://ls1tech.com/forums/generatio...ls-blocks.html

 

Just looked at your thread and you're right that the difference is going to be closer to a 110lbs gain in weight if going to an iron block. At the end of the day if I went with a 5.3 did all the machine work I'm only going to save a couple hundred bucks and be taking on significantly more risk.

A friend of mine was telling me a story today about picking up a used block. He said the block looked good, however he found that there were several bolt holes stripped out on it requiring helicoil kits and in one case a machine shop's intervention to repair. His point was that when the margin is so slim in going used over new, pony up and go new.

With that in mind I'm going to go with a brand new LS1 short block. It's going to run me a grand shipped. First thing is first though I need to finance the new short block. Tomorrow I'm going to pull my Z06 seats and put them up on craigslist in hopes of fetching a few hundred bucks and going back to my coupe seats. Also hoping to get a 100$ for my cracked block, maybe someone is looking for an ls1 coffee table. I hope to have ordered the block by the end of the month, will post back when I have pulled the trigger.

 

I'm not really trying to sell my ls1 block, there's not a thing wrong with it. Well I'd probably sell if I got a decent enough offer. I'm surely not giving it away. I never listed it & got some $200 offers from people that knew I have it. I know shipping costs are an issue also.

I spun a bearing in the ls1 & wanted to go bigger & was looking for an ls3 block & looking at different aluminum & iron short blocks on ebay. I found a used ls3 block on Craigslist, wanted $800 but I didnt jump on it soon enough. I decided to spend a lil more & buy an ls3 block for my build to keep the weight the same. Glad I did cuz I seen some guys that added an iron block complain about the front end sitting 1.5 inches lower. That would've been a bigger problem since my car is lowered. Easily fixable with some springs but I just didnt wanna add 100 lbs my car is close to full weight as it is (3400 w/ drag wheels, spare & jack)Summit seems to be the best deal on ls blocks, it was $1520 & free shipping.

 

http://www.gmpartsdirect.com/results...umber=12561166

 

I hadn't considered by switching to an iron block that very likely could require a suspension change to accommodate the weight. That would also be another cost in going to an iron block. Honestly going to an iron block is drastically cheaper than going for a new block.

The cheapest I've seen a used iron block locally go for is 200$, if you have to drop a 100$ in springs, 500-600$ in machine work to fit 5.7 internals. At that point you're already at around the cost of a brand new ls1 block. Not to mention you could be out the cost of the used block if the one you selected comes back too thin in areas from sonic testing.

Thanks for the heads up.

I'm currently in the process of selling my cracked block, found an engine builder willing to give me 150$ for it that wants to run it in a stock configuration. Got my Z06 seats going up for sale today and also put up for sale my old exercise bicycle, with any luck if this stuff sells I will only have to pony up a few bucks out of pocket.

 

That didn't take long I have just about raised enough funds to pick up a bare block. Is there any difference between the block jegs, texas-speed, summit or gmpartsdirect sells? I would like to select the cheapest one assuming it's an apples to apples comparison. I read a thread regarding summit's 6.0 blocks and it sounded like they were actually used blocks machined by ATK, which has made me apprehensive about purchasing my bare block from them.

If only one of the companies assumedly, gmpartsdirect, offers a brand new block I would spend the extra few bucks and go with them if there is a difference in quality. Any opinions on which company to purchase the best bare block I can for my money with the least amount of quality control issues would be appreciated. Thanks guys.

 

Anyone advertising the engine block under GM number 12561166 should be selling a brand new never used block.


I don't see anything in any of the sale offerings from the various sellers that would lead me to think it's a used or reconditioned block.

I do know that unless an ad says differently, it's brand new.


Short or long block assembled engines usually use seasoned (used) engine blocks.


I don't think you have anything to worry about when buying GM part number 12561166, you'll be getting a brand new un-used block. You can always contact the seller and confirm.

 

Thanks paul, reading of 'seasoned' blocks made me think that I might not be picking up a brand new gm block. I'm going to call summit tomorrow to make sure. Thanks.

 

Summit was indeed offering a brand new block from chevy for item number 12561166.

Placed my order and am having it shipped directly to the machine shop. Going to stop by in a day or two at the machine shop and drop off my rotating assembly and stripped down heads. Hoping to have all my parts back by the 1st of October so I can begin the process of getting my car running again.

In the interim I installed a new slave cylinder and tick remote bleeder. Praying it won't leak when getting it back together.