Datsun Roadster Forum-311s.org

Nice work indeed. I built my own log turbo header (way,way,way easier than this header build), down pipe and full exhaust out of stainless. I too was self taught on a TIG. Those that haven't tried to TIG far underestimate how hard it is to even get marginally acceptable results. Hours and hours of practice, and mountains of scrap. It's so frustrating, especially if you're a bit older and the hand/eye coordination isn't what it once was. I have only the highest praise and admiration for those that can lay down a nice stack of dimes the whole way around a tube.

Regards,

Steve

Well, two steps forward, one step backwards. I've decided to attempt a new route for tube #3. The original combination of 90 deg bends was due to my original plan to have tube #2 mirror tube #1 coming out of the flange. However, I could not get a cut on that tube that would allow a clean match with the connect tube (it would want to hit the engine). Once I found this tight radius bend I now have on tube #2, it allowed me to not only connect, but to move it closer to tube #1, giving me much needed runner length. So now I have this big gap that is not needed between tube #2 and #3, and further, the combination of 90 degree bends requires 3 welds. I believe I can get it to 2 on that tube. I've ordered a couple more bends, and one that may prove exceptionally good for tube #4. But this will require several days pause to get the parts. But now is the time to straighten tube #3, which will allow me to optimize tube #4 based on that.

Also, I can slip the header in and out fairly easily, however, there is one part of the frame that sticks over that could be cut out to make an even easier install; I will eventually do it to mine (although I want to leave it there for now so I can verify that the install could work for others w/o cutting).

I got my 45 deg and 120 mandrel bends in, and unfortunately, I need about 125 deg to really do what I hoped in the 4th tube (get only one intermediate weld in). Also I hoped to use the 45 deg tube on #3, but that won't work. But after reviewing many other detailed header builds almost everybody has 3-5 welds per tube. So, I'm just pressing ahead with what I have. I'll finish the prototype (which could be the final design) and then put the jig together to do fine tuning on the design and then be able to build these. I finished the 4th tube tonight, and I can see exactly how I want to do tube #3 now; shouldn't be too hard so I hope to have the prototype done in the next few days.

I did have a tough time getting the header in w/tube #4; as I speculated earlier that one part of the frame I had to grind off (it just sticks over and does nothing structural). When I get the engine out I'll weld the corner of the two sheets good and tight before powder coating. For anybody interested that already has their frame powdercoated, you could just put the header on before installing the engine, or loosen the engine and tranny mounts enough to move the engine to get room(EDIT Update: Shannon's install suggested this was almost impossible). Or just cut it out even w/frame done and go back w/some por15 in that one spot. In any case its tight to get in and something has to go. And I haven't put the tub back on yet; that may make install even harder! Bottom pics show interference; the first shows it installed after I cut out the small piece (went in pretty easy then).

Getting closer. Tube #3 is in, with design close. However I'm hitting where I think the steering shaft will be, but there is room to move that in. I'll be pulling that tube out and I'll cut off about 1/2" and see how that works. Its also very hard to get the two flange pieces on as is, but I might be able to improve on that with the adjustment to tube #3. Also, where it is now leaves collector almost touching the tranny; hopefully I'll be able to solve all these when I adjust tube #3 inbound. But I am very happy with the overall look and runner length. After I do these adjustments and get happy, I need to finish the rest of the exhaust, and then get the tub back on with the actual steering column and see where I am.

GoldHawg wrote: ↑Thu Jan 24, 2019 9:59 pm Getting closer. Tube #3 is in, with design close. However I'm hitting where I think the steering shaft will be, but there is room to move that in. I'll be pulling that tube out and I'll cut off about 1/2" and see how that works. Its also very hard to get the two flange pieces on as is, but I might be able to improve on that with the adjustment to tube #3. Also, where it is now leaves collector almost touching the tranny; hopefully I'll be able to solve all these when I adjust tube #3 inbound. But I am very happy with the overall look and runner length. After I do these adjustments and get happy, I need to finish the rest of the exhaust, and then get the tub back on with the actual steering column and see where I am.

Looking awesome! I've always dreamed about doing something like that for my U20

I now have the header dimensions perfect to build a jig; something like what you see in the pic. Good clearance all the way around. Booked all weekend; I'll work on connecting the rest of the exhaust next week, then the body back on to verify steering shaft clearance then weld up. I'm working with a few sources to potentially take my prototype and recreate the tubes with a CNC mandrel bender. If that turns out to be possible, it will be much easier to duplicate this design (based on Spriso motor mount location).

Wow, congratulations on this huge project! Beautiful!

Been trying to decide on the exit strategy, and I decided to shorten the header collector length to fit in a 6" 2.5" flex joint. I have one minor interference thru my cross member (touches about 4 o'clock position). I'll end up grinding that down, or heating w/a torch and hammering it a bit in there to give the exhaust clearance. I think the O2 sensor has to go where the picture shows to give relatively easy access but still be slightly above the bottom of the tranny. That's really the only spot available unless I move the sensor just in front of the cat behind the hole in the cross member. But I'll wait until I have the body back on to make the decision; it might be possible to get from above as well.

Unfortunately I'm going to have to mod tube #2. With the body back on, the steering shaft hits; hopefully I can just shorten the one I have, but I suspect I'll have to just build a new one. I have about 1/4" clearance on tube 1, and plenty on 3 & 4.It always seems like a small cut changes the dimensions elsewhere. Anyway, I'm getting very close to final.

One step forward, two steps back. I modified tube #2, and was able to get about a 1/4" clearance on both tube #1 and #2 (much more on 3 & 4). So I can use this and build a jig to hopefully get better. However, my design was based on the modification I made several weeks ago, when I found the super tight radius stainless steel bends being sold by Vibrant. That enabled me to change several of the tubes. But in shortening tube #2, I just built a new one, and as I looked into the new tight bend I was starting from, I saw what looked like rust from the mandrel bending fluid inside. I cleaned it up, but in my bending the entry in the die to go into the header flange, I felt attraction between it and the high powered magnets I was using to hold the die to the vise. It turns out--for this piece only!!--Vibrant used 409 stainless, not 304 as they do in other bends, and the copy only said SS--did not indicate the type. I can't use 409 in the final design as it will turn a different color faster and darker than the 304. But it will allow me to build the jig and optimize my design on the bench.

Aargh!

Wow man, quite the process. Ah, one more thing... the O2 bung needs to be less than a 90 degree angle, at least per the wideband installation instructions I've seen.

Gregs672000 wrote: ↑Sat Mar 09, 2019 8:58 pm Wow man, quite the process. Ah, one more thing... the O2 bung needs to be less than a 90 degree angle, at least per the wideband installation instructions I've seen.

Thanks....I hadn't seen the angle issue, but I would've done the right thing by accident anyway. Now that I've got the body on, I've found a pretty clear shot from the top to the collector, so the actual sensor install will be about the one o'clock position (recommended at least 10 deg above 9-3 o'clock positions). It will take several socket extensions to get to it if it needs replaced, but that's not a problem.

Jig is pretty much ready; have to add one more brace to fit the new style merge collector (slightly different) I'm building on the first one. The key critical dimension is the steering column which I think I have accurately captured.

Edit update, now the jig is complete. Hopefully make a design that will work out well.

Certainly is BEAUTIFUL!

Yep, that is a work of art! (Like a Picaso, or a Garfunkel)