BlueStag Posted May 18, 2012 Share Posted May 18, 2012 Just kill me now. This damned 260 cast iron exhaust manifold is killing me. Years ago, when I first worked my engine swap (L6 into Triumph Stag) one of the studs had failed and I helicoiled it. Of course, I had forgotten. I was using an original down pipe, rusty and banged around, which the muffler shop used to build a custom rig to fit the engine to the car. As those who have been reading the painful story of my car will know, I had it up on stands for 9 years and only got it down last August. I noticed how noisy the exhaust flange was, clearly it was leaking. Took it apart, tried to get the original down pipe flange to level out, no chance. Down pipes are not available separately. Tony hooked me up with another enthusiast who sold me one for silly money, new MSA rig with a flange thick like nothing else. While I was wrestling with the whole mess, I wanted to eliminate the air injection hardware, managed to shear off a stud. (I was replacing the throttle bodies so I had all sorts of stuff torn apart) I had forgotten that I had some helicoils, so I took it to my shop. The guy sort of lost track of what he was doing, and drilled it for a 10mm heli rather than and 8mm heli. OK, I own a lathe, these sorts of things are cool. I made a stud 10mm at one end and 8mm at the other. Stuffed that in. Got the MSA down pipe in place and crawled under the car with my wrench and extensions, and what do you know? I pulled the helicoil from 13 years ago out. Here is the cool thing: IT IS POSSIBLE to take SU induction off as a single piece, even without pulling the chokes off (those need to be balanced). I was able to get the exhaust manifold off an hour after I started. Upon inspection, the pulled heli was not going to permit a 10mm, it was just too gone. I drilled and tapped for a 12mm grade 8 and drilled and tapped that for 8mm. I'm pretty sure the 12mm thread will hold in the cast iron. Put it together. And it leaks. Take it apart, be very careful that the down pipe is not constricted in its alignment, tie it back together, and the goddam thing leaks. My budget is constricted just now. I am looking for a solution that is not buckets of money. Although a tubular header is looking good just now. Is there a process to machine the cast flange flat? I am sure the MSA flange is flat enough. Quote Link to comment Share on other sites More sharing options...
jasper Posted May 18, 2012 Share Posted May 18, 2012 Read your whole post, can't figure out where your leak is ?! Be less wordy, and more precise. FYI,..high temp silicon works wonders...... Quote Link to comment Share on other sites More sharing options...
letitsnow Posted May 18, 2012 Share Posted May 18, 2012 Is there a process to machine the cast flange flat? I am sure the MSA flange is flat enough. Bring it to a machine shop and ask them to machine it flat? Quote Link to comment Share on other sites More sharing options...
BlueStag Posted May 18, 2012 Author Share Posted May 18, 2012 Read your whole post, can't figure out where your leak is ?! Be less wordy, and more precise. FYI,..high temp silicon works wonders...... Not clear??? It is leaking at the flange. The flange where the exhaust manifold meets the down pipe. That was all I wrtoe about. Well, and some pulled studs. Quote Link to comment Share on other sites More sharing options...
BlueStag Posted May 18, 2012 Author Share Posted May 18, 2012 FYI,..high temp silicon works wonders...... Oh, and I had tried that at one point. Did not mention it. Was getting too wordy. Quote Link to comment Share on other sites More sharing options...
BlueStag Posted May 18, 2012 Author Share Posted May 18, 2012 Bring it to a machine shop and ask them to machine it flat? Yeah, I think that is the answer, if it can be done. I suppose if cast iron blocks can be machined flat, a manifold can be. Quote Link to comment Share on other sites More sharing options...
BlueStag Posted May 18, 2012 Author Share Posted May 18, 2012 Oh, and try taking a pair of SU's with their intake runners and balance tube off all as a single component some day. That is good fun. Hint: one needs to take the heat shield off early in the process. But you can leave the choke cables attached, and that is a good thing. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted May 18, 2012 Share Posted May 18, 2012 Yeah, I think that is the answer, if it can be done. I suppose if cast iron blocks can be machined flat, a manifold can be. It can be done, I'm sure it'll be a pain to fixture, but it can be done. Quote Link to comment Share on other sites More sharing options...
DatsunZman04 Posted May 18, 2012 Share Posted May 18, 2012 I guess I should have read your post first, I am having the same issue with my cast header also. I just dont wanna tap and put in larger studs to tighten down a lowsy 3 bolt flange. Good luck to you Quote Link to comment Share on other sites More sharing options...
BlueStag Posted May 19, 2012 Author Share Posted May 19, 2012 I guess I should have read your post first, I am having the same issue with my cast header also. I just dont wanna tap and put in larger studs to tighten down a lowsy 3 bolt flange. Good luck to you Got sent to a good muffler shop today. The guy there smiled gently and told me that he would have no issues grinding my manifold flat. Yes, tapping cast iron is a pain, especially old stuff like this that will have hard and soft regions, after 40 years of heating and cooling. I fully expect to shear off the last of my original studs when I next take it apart. And I'll drill and tap it for a 12mm plug that I will then drill and tap 8mm. Quote Link to comment Share on other sites More sharing options...
BlueStag Posted May 19, 2012 Author Share Posted May 19, 2012 It can be done, I'm sure it'll be a pain to fixture, but it can be done. Found the right muffler guy today. He said it would be so easy, assuming that I brought it to him off the engine with the studs out, that he could not bring himself to charge me for it. He said he could make it flat in less than 5 minutes. Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 20, 2012 Share Posted May 20, 2012 SOB! There has to be something working that manifold. Is your exhaust clear through those chassis holes out back? Only thing I can think of is when the engine is torquing over, something in back contacts and puts a strain on the flange. After a few cycles, it begins leaking. With the studs out of the manifold, getting it flat is a simple matter of a second on a belt sander and maybe some figure-8's on an Emory cloth covered glass lapping surface. After its dead flat, if it happens again consider using a flexible joint between head pipe and the rest of the exhaust. Or convert to turbo, it uses a conventional exhaust donut to seal! Quote Link to comment Share on other sites More sharing options...
BlueStag Posted May 20, 2012 Author Share Posted May 20, 2012 SOB! There has to be something working that manifold. Is your exhaust clear through those chassis holes out back? Only thing I can think of is when the engine is torquing over, something in back contacts and puts a strain on the flange. After a few cycles, it begins leaking. With the studs out of the manifold, getting it flat is a simple matter of a second on a belt sander and maybe some figure-8's on an Emory cloth covered glass lapping surface. After its dead flat, if it happens again consider using a flexible joint between head pipe and the rest of the exhaust. Or convert to turbo, it uses a conventional exhaust donut to seal! Tony, I have the manifold out. Had to hack off the last original stud and helicoil. I put in a flex pipe a few months ago when first I was struggling with this. But the current arrangement does have the down pipe hug the underside of the floor very tightly. I have a muffler shop offering to face off the manifold for free, which is a price I rather like. I'll take it in tomorrow. I hope to see a very much cleaner surface when he is finished. I don't know that I'd be able to sand it. It has definite areas that are much harder than others. But I'll ask the muffler guy to bias the flange slightly such as to drop the end of the down pipe away from the floor a bit. As for a turbo, I'll be counting on you to find me one like you did this down pipe, thanks again. I will be looking for as full a package as I may get, in the hopes of a very rapid swap. Possibly I can sell my SUs for $300 when the day comes..... Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted May 20, 2012 Share Posted May 20, 2012 Did you end up with that MSA head pipe Tony swipped up at the last show? LOL Do any of the head pipes you are using have the pipes extending past the flange into the manifold? Or are they all flat? Just curious really. I have slapped on some warped crusty head pipes onto these manifolds and as long as I use a fresh gasket and those head pipes with the slightly extended pipes that reach into the manifold collector I almost never have a leak. One of the head pipes I used was warped 1/8" at least on each outer bolt end. I double gasketed that one and it was fine for a few years before I swapped the engine out. I do not like the 260Z manifolds either. The material always seems to be 'softer' or 'more brittle' than older manifolds or later ones. The worst offenders though by far were the late 80's CA18e manfolds and cylinder heads. Both the aluminum and cast iron components might have well been made from red brick. Go ahead and try and heli-coil one of those and you will either go ape crazy on it or shoot yourself... Once you calm down you will realize its time to get a CA18de/VG30 or buy a new car. There was a guy in a suburban across the street at MSA pushing some ray-jay turbos on dyno day... But I did not get his number, and I laughed after he said he wanted $175 for a brand new MSA twice pipe kit... like the 2 I had just bought for a combined total of MUCH less during the swap meet there. Maybe try using double gaskets with those new fasteners unless your flange does not have those protruding pipes I mentioned. I can post a picture of what Im talking about if need be. Ray Quote Link to comment Share on other sites More sharing options...
BlueStag Posted May 21, 2012 Author Share Posted May 21, 2012 Did you end up with that MSA head pipe Tony swipped up at the last show? LOL Do any of the head pipes you are using have the pipes extending past the flange into the manifold? Or are they all flat? Just curious really. I have slapped on some warped crusty head pipes onto these manifolds and as long as I use a fresh gasket and those head pipes with the slightly extended pipes that reach into the manifold collector I almost never have a leak. One of the head pipes I used was warped 1/8" at least on each outer bolt end. I double gasketed that one and it was fine for a few years before I swapped the engine out. I do not like the 260Z manifolds either. The material always seems to be 'softer' or 'more brittle' than older manifolds or later ones. The worst offenders though by far were the late 80's CA18e manfolds and cylinder heads. Both the aluminum and cast iron components might have well been made from red brick. Go ahead and try and heli-coil one of those and you will either go ape crazy on it or shoot yourself... Once you calm down you will realize its time to get a CA18de/VG30 or buy a new car. There was a guy in a suburban across the street at MSA pushing some ray-jay turbos on dyno day... But I did not get his number, and I laughed after he said he wanted $175 for a brand new MSA twice pipe kit... like the 2 I had just bought for a combined total of MUCH less during the swap meet there. Maybe try using double gaskets with those new fasteners unless your flange does not have those protruding pipes I mentioned. I can post a picture of what Im talking about if need be. Ray Now now. Tony is a gentleman and a scholar. He has been very good to me. No, he connected me with another enthusiast at the MSA clear-out who sold me a down pipe for next to nothing. That down pipe has no extension of the pipe beyond the flange. The gasket before this last, when I took it out, clearly said that the exhaust was escaping above it and straight toward the back of the car. Can't change cars. Mine is a Triumph Stag. It is my only car. Let me tell you, it is a rare day indeed that I take it out and not get positive comments. And only once so far from some guy who I suspect has never seen a woman naked. Even without paying for it. When I was committing Tony to finding me a turbo, I meant to say a complete package. Engine, induction, exhaust, ECU, what-have-you. Everything that you would hope to have in place the day that you pulled the L24 out of your 240, with the hopes of getting back on the road in a hurry. I have found the cast iron to be challenging to tap, but not impossible by any means. Quote Link to comment Share on other sites More sharing options...
Sam280Z Posted May 21, 2012 Share Posted May 21, 2012 Biasing the flange might not be the best idea. Your studs will not be perpendicular to the flange surface. This will cause the nuts to seat at an angle and the load will be at a single point. This will cause the metal to deform there and the nuts will not stay tight. You could source some self aligning washers to prevent this, but it may be easier to just have the exhaust pipe bent out of the way a bit. Sam Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted May 21, 2012 Share Posted May 21, 2012 Just curious what muffler shop did you go to? And if this problem persists I really think you should go with some headers. You've been fighting this demon for a while now. Also going with going turbo, the hardest part for me would be the electrical. You're trade should help you with that. Quote Link to comment Share on other sites More sharing options...
BlueStag Posted May 21, 2012 Author Share Posted May 21, 2012 Just curious what muffler shop did you go to? And if this problem persists I really think you should go with some headers. You've been fighting this demon for a while now. Also going with going turbo, the hardest part for me would be the electrical. You're trade should help you with that. Moris on Burbank by the Five Points. I'll direct you there when next you are in town. As for a header: that is over $200 for a single component. Swapping to a solid un-rebuilt stock zx turbo, assuming that I could get lucky enough to get a little help from my friends, will cost me what? $1000 to $1500? I'll save my pennies. Quote Link to comment Share on other sites More sharing options...
BlueStag Posted May 21, 2012 Author Share Posted May 21, 2012 Biasing the flange might not be the best idea. Your studs will not be perpendicular to the flange surface. This will cause the nuts to seat at an angle and the load will be at a single point. This will cause the metal to deform there and the nuts will not stay tight. You could source some self aligning washers to prevent this, but it may be easier to just have the exhaust pipe bent out of the way a bit. Sam I'm talking about a few thousands of an inch. The flange is less than three inches across. The drop pipe is about two feet long. Six thousandths translates to .050th at the rear tip or there abouts. Which can help. A slight difference like that will be OK at the studs, which will flex over a thou or two at the end of the torquing, and all will be flat. Quote Link to comment Share on other sites More sharing options...
Sam280Z Posted May 21, 2012 Share Posted May 21, 2012 True. It sounded like you were trying to move it a more substantial amount Quote Link to comment Share on other sites More sharing options...
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