underdrive pulley bolt
not just cheap insurance, its required. The stock bolt stretches when it is torqued (torque to yield) so it must be replaced, should be able to get one for about $5 at the dealership.
yep, new bolt. also you will want a longer bolt or preferably some threaded rod and some heavy duty washers and nuts to seat the pully on there. the stock bolt wont reach the threads enough without getting the pulley on there a couple inches.
You will hear plenty of guys tell you they have used the stock crank bolt several times. The fact is it is a torque to yield bolt and should NOT be used more than once!!! I could understand it being hard to justify if it was a $100 part but its only a few bucks. As already stated, you may need a longer bolt to seat the new pulley on the car. You can find it at NAPA for $7. The bolt size is M16 x 2.0 pitch x 120mm long. There is another way if you dont want to buy the longer bolt. I did this on my last head/cam install. I put the pulley in the oven and set it at 200 for about 30 minutes. Then I took it out and rubbed a little bit of motor oil on the inside lip to eliminate any friction between the pulley and the crank. The heat helped it expand enough to seat on the crank snout a little bit further. Then I took a piece of a 2X4 and set it flat against the pulley and hammered it on little by little. Now, I only did this cuz it was very late and I didnt want to wait til the next day to buy a longer bolt. Do yourself a favor, buy the longer bolt and a new crank bolt. Good luck
+1 on the oven trick. You can put it out in the sun too, if it is hot out!
BTW, if you don't have them right now, you're going to need a breaker bar and a 3 foot pipe that fits over it. This will give you enough leverage to take the old bolt off.
BTW, if you don't have them right now, you're going to need a breaker bar and a 3 foot pipe that fits over it. This will give you enough leverage to take the old bolt off.
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Almost as fun as torquin it back down when you put the new pulley on 
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