The the exhaust manifold bolts can break when changing to headers. This espically true on upper bolts that are exposed and subject to corrosion at the back of the bolt. Without taking the head off, to drill ez-out and helicoil, does any one have any secret solutions? The bolt in question is on the passenger side, cylinder #8 upper exhaust flange. I really don't want to get into pulling the mill or head on the old 350. The stud extractor tool we tried on what little stud protruded just broke it flush with the manifold flange. Tom
If I understand correctly, this is the upper bolt closest to the firewall? Do you have A/C? If so, I don't really see a way to get it done without pulling the head. ou: If you don't have A/C and have enough room to actually get in there to work (possibly through the wheel well?) you may be able to get this done without pulling that head. First, start spraying that bolt hole every few hours with PB Blaster. This stuff is pretty amazing. After you do this for a day or so, find a drill bit tough enough to get a hole into that bolt/tool steel extractor. Sink it as deep as possible without drilling into the head itself. While you are doing this, be sure you keep the hole going straight along the bolt hole and don't mess up the existing threads. There are a couple of ways to get extractors to work. One is to use the smallest size that will do the job so that once it starts to move the remains of the bolt, you can grab it with a pair of channel locks or vice grips. The other way takes some guts and a lot of care. This is normally for bolts/holes that are pretty corroded. Use the largest drill that won't damage the threads in the head and follow the old bolt to the bottom of the existing hole. This will get rid of the biggest portion of the bolt. Then use either the tap that fits the bolt hole or the next size down, whichever actually fits to chase the threads. If you use the smaller size, you'll have to go back to the proper size after anyway. To do the helicoil, it's fairly simple. Use the recommended bit size, drill out the hole, tap it with the proper tap and insert the coil. What happens is the drill takes out all of the existing threads and leaves a clean hole to tap for the coil. I have to say that unless you have a lot of room to work, you will be time, skinned knuckles, frustration and possibly parts ahead by just pulling the head now and doing all of this on a bench. It's pretty tough to do any intricate work standing on your head or bent up like a pretzel! :TU:
I just pulled the exhaust maniforlds off my 455 and got all but 3 bolts broken off. Luckly the heads are going to be scrap.
I broke off a bolt extractor as well years ago and had to have a machine shop fix it by welding up the hole after drilling it out then adding a Helicoil. Was not much MEAT left on the top of the hole. every time I have tried bolt extractors they snap off? real brittle metal.
I'm pulling this one. For what great effort it is to work on #8 cylinder in the car, even with no air, there is still the driver's side to unbolt and another possible broken one or two studs. Tom
