Hello! I have a '71 Mav, 200 engine. I have a feeling that the gasket is shot because I'm getting smells inside. I've felt the exhaust pipe nearly the whole length, without feeling any holes and the muffler seems solid also. I've replaced the e-pipe "O" ring awhile ago which definitely helped with smells and engine sound. I have no problem doing the labor on removing the nuts with the star washers (or whatever they're called), but my concern is tightening the nuts on the studs--will torquing them possibly snap the 45 year-old studs? Should I just remove & replace all the studs? I was able to grip around part of the manifold. I didn't feel any of the gasket that wasn't being used. Had that just burned off in time, or should I have been able to feel it between the ports? Thanks for your help!
a too rich carb. will give the same smell. did you have the manifold mounting surface checked/milled when you had it off?
Worry about tightening AFTER you remove the bolts/nuts without breaking them... Check the manifold mating surface to be sure it isn't warped, fairly common issue...
Thank you for responding! I hadn't thought about checking the mating surfaces--more things to worry about!
I wouldn't touch the bolts or studs without heat. Also watch the 'ear' tabs of the head at the front and rear exhaust ports! I have had the tab break in half on several heads in the past! It's hard to tighten a bolt to hold a manifold on if half the threads are missing in the head! Use heat, go slow and replace the studs once you get the manifold off.
Hello! Thank you for responding! Would that be to use a heat gun that's used for stripping paint, etc.? Should I spray PB Blaster on the studs, letting it dry before using heat?
I doubt a heat gun will get the metal hot enough. I was thinking Oxy/Acetylene, but even a small propane torch might be enough. PB Blaster or Kroil would be good to soak the threads. I wouldn't worry about drying it completely off. As soon as you hit it with a torch, it will dry... The key would be to spray it with the penetrating fluid and then leave it for a day or so to soak into the threads. The threads are exposed on the very front and very rear top bolts, and those are the ones that the piece of the head is prone to breaking.
A good heat gun can reach 1000 degrees F but a propane torch can reach 3600 degrees F. An Oxy/acetylene torch can reach 6300 F and of course can cut steel. Just don't have butter fingers and drop the torch. Safety first! MD
Thank you for your response! I'm a bit hesitant to get a torch in there. What I'm not getting is how a directed heat source is going to loosen the bolts (after using PB Blaster). Won't the heat expand the metal, making it more difficult to remove?
You do not heat the bolts directly. You heat the surrounding metal which causes it to expand. There is some heat transference to the bolt but not as much as what is being applied directly.
A heat gun won't even come close. You can go to any hardware store and pick up a propane bottle torch. That will probably be the cheapest way. A butane torch would work but it depends on the size. Remember to not heat the bolts themselves. You want to heat the surround metal. Do not stay in one place the whole time try to go in a circular motion around the bolt to expand the surrounding metal.
