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I have a used LS1 long block that I want to swap in to a older 4th gen. Went to check the bearings in the bottom end this morning, and 4 of the main bearing bolts almost snapped coming out. By that I mean the only thing holding part of the threads on was the external part of the thread. Is this common on removal?
From searching it does not seem that the main bolts are TTY. I am thinking I should replace all the bolts just to be sure though. What is the best source for them? Thanks
Hello how's it going ? I suppose not the best. Yes the main bearing cap bolts are TTY ,,,,,,,I probably should have looked around because I spent $90 on the main cap bolts and a harmonic balancer bolt from a Chevy dealership .
And Wow thats kinda weird sounds like You're situation may be somewhat unique although I don't believe the main cap bolts are as course a thread pitch as the cyl head bolts which are 11mm / 2.0 pitch which is extremely course ,,,,I can't believe the head bolts don't strip especially the aluminum blocks given the amount of TTY or the yeild part which is almost 1/2 turn after first torquing them to 22 lb. ft. . Well anyway Summit racing or if You have a penny pincher type of auto parts retailer in You're area or there are quite a few poeple that have purchased head bolts and rod and main bolts from E-bay and many sware They are quality and many that don't trust the quality ,,,,,,,They are inexpensive ,,,,,anyway good luck
Need pics.
Main bolts torque via the angle method. But they are not TTY bolts.
Almost sounds like a prev owner way over tightened them and the threads pulled out.
But can't tell by your description.
I don't think the threads pulled just because there is no aluminum on the threads, came out clean. The motor has jasper stickers on it, so maybe they over-tightened them?
I have done some work on Northstar engines in the past, and it is pretty common for their main bearing bolts to snap off on removal. Figured this was pretty normal for LS engines too but after doing some google searches couldn't find anything out about it.
Those bolts were over tightened. They yielded in the un-engaged threads.
Time for a new set from GM. OR pony up the bucks for a set of ARP studs-which are waayy better.
Makes sense. What's the best place to get a new factory set?
Originally Posted by bbond105
If going with ARP studs some say the block will need to be line honed.
That is the main reason I would probably not go with the studs. I only pulled these caps to check the bearing condition. Just want to get the thing back together to run it.
I agree, they were almost certainly over tightened.
I've only checked a few blocks with the OEM bolts vs. ARP studs and from what I've seen with the ARP studs, it's hit or miss. Sometimes the main bores are on the loose side of the acceptable limits and the ARP's will just push them over so a line home is needed. Most shops just automatically line hone when using the ARP's.
I agree, they were almost certainly over tightened.
I've only checked a few blocks with the OEM bolts vs. ARP studs and from what I've seen with the ARP studs, it's hit or miss. Sometimes the main bores are on the loose side of the acceptable limits and the ARP's will just push them over so a line home is needed. Most shops just automatically line hone when using the ARP's.
I think I will probably just go with stock bolts for now.
Originally Posted by RonSSNova
Wow. I bet you are happy the thread didn't break off in the block.
New bolts and you should be good to go.
I'm going studs in mine. My guy will line hone. I think he would line hone a lawn mower if he was rebuilding it.....
Haha sounds like a good builder. I am glad they didn't snap off, but have been there, and done that with the Northstars. Not that bad really. put a cup of tape around the hole, center punch the bolt, drill it and use a easy-out. Usually comes right out.
Originally Posted by Paul Bell
I guess I've been lucky. The times I've stepped up to studs my measurements were all still good.
Of course, always measure to be sure.
Yeah I don't really want to deal with all that right now, so stock bolts it is.
Makes sense. What's the best place to get a new factory set?
That is the main reason I would probably not go with the studs. I only pulled these caps to check the bearing condition. Just want to get the thing back together to run it.
Iv got some used factory main bolts if you want a few
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Broken Main Bearing Bolts 
