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Header bolts/stud kits
For LS engines, do we really need these fancy pancy ARP header bolts or stud kits? The bolts are $45USD from Summit or over $70 locally, and the stud kit is over $150.....whats wrong with grade 8 bolts? Its not like these things get reefed on tight...they're only M8....am I missing something?
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on the race car I use arp for everything cheaper bolts in the headers gradually corrode in and snap they all need a tweak when there first put in esp cheaper bolts as they stretch a bit . if you snapped a cheaper bolt and you had to try a nd drill and tap it out you would be wishing you had used arp bolts . at the end of the day its not a lot extra on the build cost .
cheers dean |
With aluminum heads any bolt that is made of any material grade 5 or better will work. The threads in the head will fail before the bolts. For my pan I purchase hardened studs at the farm implement store and use mechanical locking jet nuts.
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Tighten to the factory spec which will be based on a safe thread strength margin and ensure the nut or bolt has anti vibration to stop un-threading. i.e. serrated face nuts bolts or a lock washer. |
I have been using the factory bolts on mine.
Unfortunately I have had to remove and fit them many times and have had no issues. Ensure you anti-seize them though. |
Just some thoughts
One of the things I find a bit strange with US engine building is why exhaust bolts come loose A LOT.
Have spent way more years than I care to remember working on HP Jap engines and for the life of I can not remember or re-call this being ever an issue. My observation being that ALL the engines that I've worked on were all internally balanced, and don't suffer from the harmonic vibes that externally balanced engines seem to. Maybe I'm missing something but I don't think so. Maybe someone can shed some light on this. Either way whenever I work with aluminium parts and steel bolts nuts and studs my NeverSieze is right there beside me. An alternative is to use Monel metal nuts on the exhaust manifold-as the aircraft industry has done since before WW2 -they rarely seize and don't vibrate off either! Rog |
Nothing special about a header bolt, except for the coating. As said above, corrosion can be a problem. The fastener needs to have a coating that can withstand the heat. Your average zinc coated or galvanized fastener can't handle the heat.
This is one of the few places on a car that a split lock washer is appropriate. The split lock washer only works when the bolt comes loose, allowing the ends of the washer to spread. Since this area is subject to some dramatic temperature changes, you want a lock washer that will work despite expansion and contraction changes. That's why you find them on a Stage 8 (brand) header bolt. I don't use header gaskets - too many failures. I only use high temp copper silicone. I make sure there is a good coating of it on the bolt threads, too. It acts like a heat resistant thread locker that's easy to remove. In the 9 years or so I've been driving this car, I've never had a header bolt come loose. |
Nothing special about a header bolt, except for the coating. As said above, corrosion can be a problem. The fastener needs to have a coating that can withstand the heat. Your average zinc coated or galvanized fastener can't handle the heat.
This is one of the few places on a car that a split lock washer is appropriate. The split lock washer only works when the bolt comes loose, allowing the ends of the washer to spread. Since this area is subject to some dramatic temperature changes, you want a lock washer that will work despite expansion and contraction changes. That's why you find them on a Stage 8 (brand) header bolt. I don't use header gaskets - too many failures. I only use high temp copper silicone. I make sure there is a good coating of it on the bolt threads, too. It acts like a heat resistant thread locker that's easy to remove. In the 9 years or so I've been driving this car, I've never had a header bolt come loose. |
I use these on everything I own with headers, C6 Z06 and Cobra. I have never developed a gasket leak with them.
World's Best Locking Fasteners & Locking Nuts and Bolts STAGE 8 |
i just used stainless steel bolts. Is that bad? Dissimilar metals was a concern with the alloy head and the factory bolts were too short with my headers.
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If I dont use arp then I too would use SS grade 8
Some interesting comments, might just as well use the arp bolts I guess |
Don't waste your money Ben. Re use the factory bolts if you have them. Or Just buy some stainless steel alen head cap screws flat washers and lock washers. The cap screws have a small head diameter which makes them good for getting into tight spots between the headers. They will be plenty strong enough. Probably about $10 for the whole lot from my local bolt guy.
Use spring washers and then flat washers to avoid the spring washer digging into the ceramic coating on your headers. Locktite will work too but may suffer with the heat long term. Cheers |
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hmmmm did some reading, here is a good summary, enough to put you off any stainless other than the ARP
Stainless Bolts--Usually very weak! | eBay |
Nothing in that puts me off stainless steel. That is why I suggest a grade 8 stainless bolt doesn't exist. I wouldn't and don't use them in structural applications. Exhaust is not structural. I have seen people use stainless for suspension bolts. Very bad cause it's brittle. Your engineer won't (shouldn't) pass any other than high tensile bolts for structural application.
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Stainless and aluminium is not a good pair....electrolysis is a big issue. If you want to use this combo....use a good neva-seize product
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