LS Gen 3 head bolt length question; the short bolts.

rebuilding a LS L33 5.3 engine.  

I screwed up and got a kit where all the headbolts are the same 100mm length. Seems I need 4 shorter bolts ( 2 per head)

Unable to find actual lengths of the shorter bolts.

Can I cut down the 4 long bolts to make the shorter ones? 

4 bolts from summit ( if i could find specs to be sure) are the same as a new bolt kit, so that sucks. You know, cause Canadian shipping exchange and taxes.

If I can, I will just go to the local bolt supplier and order the right grade of bolt with the right dimensions, just not sure of the length.

Pete

Eight long ones ought to be 155mm and there should be two short ones at 100mm, from what I can find. The data I saw says they are M11 bolts , which seems odd, and are TTY items. I would have expected M10 or M12.

What year is the engine? I think the 2004 and later engines used ten 100mm bolts, and earlier engines used the ones in the picture.

Edit: Internet says the L33 was a 2005-2007 option, so I think it should use all 100mm bolts.

Why not just reuse the bolts that came off the engine? The small ones really don't do anything and there's been plenty of instron testing to show that reused LS head bolts are actually stronger than stock and stronger than the Chinese studs. 

In reply to DeadSkunk (Warren) :

Welcome to my state. Of confusion.

I thought I ordered bolts for an L33. The engine is a 2006 as far as I know. All of the  bolts  in the kit are  100 mm. Pretty sure that the outboard bolts are meant to me shorter and torqued ( angled?) to a lower spec.

So since buying 4 bolts from Summit is pretty much the same cost as buying a full kit of 30 bolts, does anyone have any dimensions on the short bolts as far as length?   Can I juust cut a bit off the end of the 4 4xtra long ones I have?

Might be able to source them from a local supplier. Bolts is bolts no? I know they are grade 10.9 based on what is stamped on the head of the bolt.

In reply to NOHOME :

Will the 100mm bolts not all work? I found them listed as 100 or 101 mm. Nothing shorter in kits for post 2004 engines. They should all be the same. Are any bottoming out? If they are, is there a possibility there is a broken bolt stuck in the block? I asked Calvin and he concurs that they should all be 100mm.

Edit: Do you have the old bolts?

DeadSkunk (Warren) said:

Eight long ones ought to be 155mm and there should be two short ones at 100mm, from what I can find. The data I saw says they are M11 bolts , which seems odd, and are TTY items. I would have expected M10 or M12.

Probably they are 11mm to dissuade someone from using hardware store bolts.  A lot of head bolts are 9mm or 11mm.

Put the old bolts against each other thread to thread to check if they are stretched.  If they are, it will be plain as day, since they only stretch in one spot.  The threads will be offset to one side and then the other.  If the threads line up perfectly, they are fine to reuse.

IIRC the reason for the short bolts is the coolant passages in the block.  The bolts go way down to the base of the block, which is good, but the coolant passages at the front of the engine are in the way.

In reply to DeadSkunk (Warren) :

Funny you should ask if I have the old bolts.

I have 17 of the old bolts.  They are all the same length. No idea where the other 3 went since the heads were off the engine when I bought it.   There should have been 16 long ones and 4 short ones ( roughly 1" shorter).  The 17 of the same length does not make any sense.

Somewhere on line there has to be a picture with dimensions comparing the two bolt lengths. If it is just a matter of cutting a few threads off the 100 mm bolts then that is easy to do.

In reply to NOHOME :

Pete, as far as I know, there are no LS engines that require bolts shorter than 100mm. Post 2004 engines use 10 bolts,all 100mm, and pre-2004 use 8 bolts 155mm long and two short bolts that are 100mm.

And just to add to the confusion"

The engine is question is an L33 alloy block.

A search on Summit racing under L33 heads has the following specs for head bolts. This would kinda explain why the original bolts did not seem to include short bolts on the ends. 

It would also mean that I accidentally bought the correct wrong bolt kit for the job.

It would appear, based on having 17 old bolts at 100 mm long, that all of the bolts for the alloy block are the same length where the bolts for the non allow block are longer and the 100 mm bolts ARE the short ones used in the outboard positions.

Gen 3 blocks had the 2 different lengths the L33 is  an odd bird but you have to treat it like a Gen4 engine physically even though it runs a Gen3 engine management. It should be all one length on the bigger bolts. 

Chase those threads, reuse the original head bolts, torque to 65ft-lbs and call it a day. There's plenty of guys out there making at least twice the power you are going to make with this method and they reused their head gaskets too. 

In reply to RacetruckRon :

Kinda where I have landed. I try to figure out why things are done as suggested by the manual, but as you say, the L33 is an odd duck.

I do have new head bolts and I do have the angle gauge so if I can find the spec I will go with that. Else it will be 65 ft lbs and done.

In reply to NOHOME :

Yeah it's pretty much an LS6 casting that's machined like a Gen4 block.
I'd cut a groove in the threads of one of your old bolts length wise to use as a thread chaser if you don't have deep metric thread chasers. Those aluminum blocks are not as forgiving as the iron blocks when it comes to dirty threads. 

The L33 is a Gen4 block, but all it's other specs are the same as the Gen3 LM4 engine, with the added bonus of an extra half point of compression. The block is the real difference that dictates the bolt length required. You already appear to have the correct bolt kit, so I would chase all the threads like Ron says, and use the new bolts. For my Challenge engine I'd reuse the old bolts, but that's a different case.

Edit: The torque sequencing is really odd,too. LS Head Bolt Torque Specs and Sequence – Rx Mechanic