So I can not find new head bolts for my 82 2.5 iron duke in my firebird the only set i came across of ebay and i ordered turned out to be used and worse condition than mine.

Maybe Im not looking the right places, some help there would be great. If not Im gonna reuse the ones I had the car only has 64,000 miles on it so Im hoping this is the first time the head gasket has been replaced.

So what should I take in consideration upon doing this? Like should i put anything on the bolts etc?

 

I know lots of people that reused there old head bolts. But they do mostly keep them in order. I built a motor tore it apart got different heads and reused my bolts.

Maybe some more advanced guys can give you input on pro's or cons on reusing them. I know bolts can stretch after tq them so much.

 

If they "look" ok then go ahead and reuse them. If they look old, pitted, rusted etc then throw them out.

The 2.5L is an engine that can be built for performance when racing in some sort of 4 cylinder class. Aftermarket components are available. ARP makes a head stud kit for the 2.5L

http://www.summitracing.com/parts/ARP-191-4201/ (12 point nuts)

http://www.summitracing.com/parts/ARP-191-4001/ (regular hex nuts)

You could even try going to a dealer to see if new OEM bolts are available.

 

Man thanks alot i drove down to summit yesterday and was told they dont carry crap for that engine, pos lazy worker but you just answered my question ill be driving back down there with the part number

 

You need to replace any TTY (torque-to-yield) bolt that comes out of an engine. Standard bolts can be reused if they are not damaged.

I could not remember off the top of my head whether the Duke used TTY's or not so I flipped open a Haynes and it lists static torque numbers (not ft. lb + degrees) so I think you'd be fine.

 

Whats the difference between a TTY bolt and a standard bolt? Sorry for my lack on knowledge on this, Im 19 and been learning what I can as I go down the road

 

TTY deform by design so they can only be used once.

 

Torque-to-Yield bolts have a section that is designed to stretch. This allows greater clamping force vs. the diameter and number of bolts used in an application. The downside is that the bolts are destroyed upon use.

You can determine them by carefully checking the torque specs. TTY bolts will have a spec like this: (50ft. lb.s + 90 degrees) or (45lbs. + 1/2 turn). Normal bolts will just have a foot pound range.

Sometimes you can also see the stretch section of a bolt, often in the shaft above the threads.

 

So are my bolts on my iron duke TTY? There said to be to be tourqued at 92lbs?

Thank you for the info

 

Yours are not TTY.

I re-used some TTY bolts on a diesel engine once. It has 45k trouble free miles right now.

 

I just checked Mitchell and there is no mention of requiring new head bolts, so my guess would be they are not TTY.

 

Just about all modern diesels use a TTY bolt but I like rebuilding Cummins engines the best. In the head gasket kit is a head bolt stretch gauge. Cummins realizes that the head bolts can stretch over time but don't need to be replaced every time the head comes off. They provide a plastic gauge for all the lengths on a particular engine. I have 3 different gauges. You simply put the bolt against the gauge and if it touches the bottom, the bolt is stretched and needs to be replaced. With the cummins engines you torque the head bolts down in 3 stages then 90* At least that way you can torque with a 1/2" torque wrench then use a 3/4" breaker bar with a snipe to turn the last bit. The 90* is also a plus or minus tolerance so it only needs to be close to 90.

It can get costly when you need to replace 32+ head bolts just to change a head gasket.

As mentioned above, the majority of modern engines now use TTY head bolts. The simple ones have a low torque setting then 90* or 60* (2 flats). Those are easy because you can mark the bolt and the head and turn the bolt until the desired amount is achieved.

The difficult ones use some weird degree. Torque to a specific amount then turn 71*. For that you need a torque angle tool but why would someone pick 71* for a final turn. Why not a lessor torque then 90* to make it simple or more torque and 60*?

Any bolt that has a specification of torque then turn xx degrees should only be used once since you have no way of knowing if it's been deformed or stretched. All bolts stretch when torqued. That's why you torque bolts. When you overtorque, you stretch and twist the bolt beyond it's holding ability and the bolt will probably break if the threads are strong enough to hold the bolt.

Rod bolts are a good example of bolt stretch especially the cap screw kind that don't use a nut. Buy a good set of ARP rod bolts. They provide a torque spec but would prefer that you measure the bolt stretch. Measure the length of the bolt. Install and torque to spec then measure the bolt length. In a con rod, you can measure the length of the bolt after it's been torqued down. The difference between the loose bolt and the torqued bolt will give the stretch. They provide a stretched spec so you'll know if it's over or under torqued. You can also tighten the bolt with a box end wrench with the stretch gauge installed to get a precise stretch and never worry about what the torque is. If you ever take the engine apart in the future, the bolts can be remeasured when loose and any that are longer than when they were loose before have stretched and should be thrown away.

Now stock head bolts are no different. Old head bolts have gone through a lot of hot/cool cycles. They're subjected to dirty oil or coolant and are constantly being forced to stretch every time a spark plug fires. Add some boost into the engine and head bolts want to stretch even more. There's no way for you to tell what kind of condition the bolts are in especially from an old engine. If you can't afford or want to use an aftermarket head bolt or stud kit, even rebuilding an old engine to stock specs for a daily driver should have new head bolts installed which can normally be purchased from a dealer. Stud kits are far superior. When torquing a bolt, the bolt is twisting in the threads as it's applying clamping force and even with oil or moly lube, torque readings may not always be exact. With a stud kit, the studs are threaded into the block loosely and the nuts on top of the head are providing the clamping force. There no chance of damaging the threads in the block and the fine thread of the nuts gives a more precise torque.

This isn't much of a requirement for a typical street engine but a high performance engine or one that uses a lot of boost needs the better clamping force of a stud kit. If you don't want to use new OEM bolts for your 2.5L or can't find aftermarket bolts then a stud kit is the next best option.

 

^ Thanks for the clinic on fasteners.