Does anyone know where I can get some grade 8 header bolts? I've been to ever store in town and can't find any.

 

Have you tried any high performance places? You can get them from Summit,Jeg's,Scoggin Dickey,etc. if you can't find them locally.

 

try speed inc. - I hope this link works:
http://www.ls1speed.com/catagory.cfm?catagory=Exhaust

Scroll to very bottom page

 

Jegs.com has Moroso and ARP header bolts Summitracing.com has some

Do you mean 'Stage 8' with the locks...didn't see those at those sites.

 

Threaded machine bolts in fractional (inch) size are graded according to a standard put out by the Society of Automotive Engineers (SAE). These grades run from 1 through 8. Grades 1 and 2 are considered a "hardware" grade and have no "heat treatment" marks on the heads. Beginning at grade three, the bolts have heat treatment marks which are used to identify the SAE grade as follows, add the number 2 to the number of marks on the head (some nuts are coded this way too). Grade 5, the most common grade for many years would have three marks on the head. Grade 8, would have six marks on the head. Again, this only applies to fractional sizes like 1/4 X 20, meaning a quarter inch in diameter and twenty threads per inch. This is a standard size for a "National Coarse" bolt (abbreviated NC) which is typically a hardware grade (1 or 2) bolt (but not always). Most grade 8 bolts are National Fine or (NF) bolts and thus have very fine threads.

Now, all of the fasteners (nuts, bolts, studs) on domestically produced vehicles in the last several years (at least 10) are fully metric and use a metric thread designation set up by a foreign standards agency like DIN (stands for Deutsches Institut fur Normung or the German Institute for Standards). Here in the US, the American National Standards Institute, has adopted the DIN standards for fasteners which have fine and coarse versions of thread pitch all measured in millimeters. High grade metric fasteners are typically a 10.8 grade.

The exhaust manifold/header bolts are metric 8 X 1.25 which is 8 mm in diameter and 1.25 threads per mm. In fact, many of the fasteners on the LS1 series engines use this size (the water pump, the cam retainer, the cam sprocket, the oil pan, the front and rear covers, and the upper row of head bolts to name several). I use the Stage 8 brand of bolts on my headers, but there are a couple of other aftermarket fastener companies who make header bolts, too. I like the Stage 8 bolts because they have special tabs which prevent their loosening up. I think that the best way to go on replacement bolts is to run a tap in the head to clean out the thread locking compound and use either an assembly lube or anti-seize compound on the threads and under the head and torque the bolts to 18 pounds feet. Do this two or three times (about a week apart each time), then apply the retainer clips after the last tightening.

I'm sure that this is more than you might have wanted to know, but it is good information.

All my best,

Steve

 

ARP doesnt make header bolts for the LS1. They make studs but the are ungodly expensive.

 

Dont you think those are a little overkill

 

It might seem to be overkill, but I have already broke one bolt and there was one already broken (drivers side by the firewall). I have read a bunch of post of broken header bolts on these trucks. Someone even mentioned there could be a factory defect on the bolts near the firewall. When I had to get a new bolt for the one i broke i went to the dealership and had to order some. When I received the bolts they were the same size but a little different shaped. The new ones had bigger heads on them and were fully threaded. The just seemed like they would be stronger compared to the originals. I guess I'm just being paranoid about another bolt breaking because that last one was a bitch to fix and i dont want to go through that again. So if i can find some good high grade bolts for a decent price then I'm gonna get them. It's just a little insurance. BTW thanks for all the help