Aaron65 Posted October 17, 2010 Share Posted October 17, 2010 This feels like one of those threads where I'll get no response, but here goes... I eliminated exhaust manifold gaskets on my 263 because I was sick of replacing them yearly...now I have a strange problem...the #8 exhaust bracket/stud/nut combo keeps loosening up after a few miles driven. I tighten it to 30 or so ft./lbs., and sure enough, after several miles I can hear the slight ticking of an exhaust leak. When I return, the thing's loosened up to 15-20 ft./lbs. I've tried cleaning the threads on the stud, a new nut, flipping the bracket around, loctite, a star washer...soooo, any ideas? Anyone have this problem? Could I try a jamb nut of any sort? Link to comment Share on other sites More sharing options...
buick5563 Posted October 17, 2010 Share Posted October 17, 2010 Did straight 8's come with those horseshoe shaped metal nut holders? V-8's had em. You bent down two small tabs and the nut couldn't loosen. I can't imagine that a lock washer would let loose, although I am not sure that is original. Link to comment Share on other sites More sharing options...
Aaron65 Posted October 18, 2010 Author Share Posted October 18, 2010 No french locks on the straight 8...I wonder if the heat would cause a lock washer to lose it's temper, but I guess I could try one...I'm about ready to try a valve stud nut...I'm not too worried about correctness; I just drive it around. Link to comment Share on other sites More sharing options...
JohnD1956 Posted October 18, 2010 Share Posted October 18, 2010 Could the bolt be bottoming in the hole? You said there was a bracket, but do you also need something to take up the slack created by eliminating the exhaust gaskets? Link to comment Share on other sites More sharing options...
old-tank Posted October 18, 2010 Share Posted October 18, 2010 Your nuts are not loosening, the studs are stretching from the heat, but not shrinking again. You really need to get the mating surfaces straight and flat instead of using torque to bend into place. If this is accomplished, 10 fp using brass nuts will do the trick.Willie Link to comment Share on other sites More sharing options...
Aaron65 Posted October 18, 2010 Author Share Posted October 18, 2010 The manifold has been surfaced Willie...and John, the nut's not bottomed. The shop manual calls for 25-30 ft./lbs on the straight 8, so I'm not overtorquing them. And the strange thing is is that it didn't happen when I used the gaskets. And it's only this one stud...the rest stay perfectly tight always. The rear stud on a straight 8 is much longer than the rest, and uses a block to hold the last intake runner and exhaust manifold runner in place. It's kind of a weird setup, unlike the rest of the studs. Link to comment Share on other sites More sharing options...
Guest Silverghost Posted October 18, 2010 Share Posted October 18, 2010 (edited) You might try to squeeze the nut slightly in a vice to make it slightly out of round & into a sort of self-locking type of nut. A good hardware store has self-locking nuts that are peened in one spot of one or two nut flats with a center punch.The Nylock locking nuts will not work for heat reasons. This is also why French Locking tabs were used on exhaust nuts ! A second Jam nut might also work if you have enough stud length to work with ?Try cutting a nut in half lengthwise to make a jam nut ! I still like exhaust gaskets !They help with long uneaven manifolds.The gasket itself will only compress where needed.Copper Clad or woven asbestos or glass fabric with graphite exhaust gaskets are the best . The unreinforced paper style blow-out all the time ! Edited October 18, 2010 by Silverghost (see edit history) Link to comment Share on other sites More sharing options...
Ben Bruce aka First Born Posted October 18, 2010 Share Posted October 18, 2010 I think Willie may be on target. Believe I would try a new correct manifold bolt. I replaced my gaskets with copper clad ones from Olsens. Not cheap, don't know how long they will last, but so far so good. Ben Link to comment Share on other sites More sharing options...
Aaron65 Posted October 19, 2010 Author Share Posted October 19, 2010 The reason I tried to eliminate the gaskets was that that big old manifold moves around so much that it moved the gaskets, either shifting them and then burning them out, or wrinkling them up. The copper ones REALLY wrinkled toward the front of the engine--so much that the number 3 exhaust port was partially plugged by the gasket. I used a standard (non-nylon) lock nut today, and it seems to work, but I've also discovered a slight leak at the #6/7 area of the manifold. I'm wondering if I'm ever going to beat this, but to be fair, it's never been totally sealed from manifold to head since I've owned it (5 years), including 2 exhaust manifolds (1 milled), headwork (to be fair, I'm not sure if they checked the plane of the exhaust ports at the machine shop), and numerous gasket sets...I wish they would have split that manifold from the factory! Link to comment Share on other sites More sharing options...
51dyno Posted October 19, 2010 Share Posted October 19, 2010 The ears are not flat and parralell from intake & exhaust .Can you post you post a picture looking down at an angle of the area that is giving you a headache????? Link to comment Share on other sites More sharing options...
old-tank Posted October 19, 2010 Share Posted October 19, 2010 Copper gasket coated with a paste made of graphite and light oil should work.Willie Link to comment Share on other sites More sharing options...
Aaron65 Posted October 19, 2010 Author Share Posted October 19, 2010 Oops...I forgot to mention that when I used the copper gaskets, I coated them with graphite and oil...now I'm beginning to understand why I'm so frustrated with this! Link to comment Share on other sites More sharing options...
Aaron65 Posted October 20, 2010 Author Share Posted October 20, 2010 Well, I think I solved the #8 loosening problem by using a locknut (not the kind with nylon insert), but there's a definite minor leak between #6 and #7. Ugh. I might just leave it. At this point, the idea of having a leak is bothering me more than the leak itself...it's barely audible...I just hate when things don't work right! Link to comment Share on other sites More sharing options...
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