Squirrel said in a post, "We need more "tech" threads." I agree. Here is my meager attempt at that. After fighting these Shoebox headers for over a week, hopefully my difficulty can help someone else. Not just with a Shoebox Ford and not just with headers. First things first..... Safety! At minimum you have to have a solid work level surface. You have to have wheel chocks. You have to have good quality jackstands. Be redundant with multiple safeties. Concrete Blocks, plywood on dirt, working on unlevel ground, cheap jackstands, ect ect ect...... This is not worth dying over. Unfortunately I know of one 25 year old Hamber who died changing the oil in his Mom's car, in her driveway. What a Nightmare!!!! Don't just think of you. Think of those that will find You!!!!!! Be Safe! This stuff will kill you. It don't give a Damn! Use, eye protection and all that jazz...... Nothing exemplifies modern times more than these 4 things, iron plate, rivets, bolts and nuts. Let's talk about the meager bolt for a moment. To work there's a male component (the bolt) and a female component ( the threaded hole). The working parts are the threads both male and female, the bolt head (male) and the nut or threaded hole( female). Without the threads it's a smooth hole, only suitable for a rivet and a rivet can't do what a bolt can do, like be removed and replaced easily. Precision out of imprecision.... It's incredible what can be accomplished with basic hand tools. A smith can make a bolt out of a iron rod with basic hand tools. The attention, time and delicacy is incredible. I'm going to use the example of the mid 18th Century American Mechanic. All he needed was either a good male component (the threaded bolt) or the female component ( the nut or preferably a screw plate). A screw plate was basically a simple threaded iron plate that was hardened. In modern terms it's a type of die. The bolt could be made into a "tap". The "tap" could be used to make a "screw plate". The "screw plate" could be used to make a bolt. That bolt could be made into a "tap" to make a "screw plate".... Above is a set of screw plate and "taps" The hole..... Our 18th Century Mechanic did not use a twist drill. The only thing that resembled a twist drill in that period was a wood auger for a Brace and Bit. The Modern Twist drill bit for metal did not come into to use until about the 1870s as drilling tools did not have a stable axis. Thus a auger style drill for metal would break. To drill a hole through metal, they used a spade bit. Above is another 18th Century screw plate, some spade bits and tumbler mills. The tumbler mills were used to machine flat surfaces in lock (flintlock) tumbler forgings. The spade bit wobbles as the brace wobbles, but it bores a hole through the metal without breaking. Then the hole was then trued with a tapered reamer. Once the hole was trued, the tapered tap was used to cut the threads precisely. I hope you can see that all this...... wobbling spade bits, very primitive taps, screw plates and reamers, could be used to make a precisely matched hole for a bolt. Precision out of imprecision. The history lesson was to plant a seed. Hopefully it will add to your mental arsenal for problem solving. With this said, you have to have something to work with.....dead is dead....unrepairable is unrepairable. Sometimes you can bring things back....if there's enough there. Sometimes not. This is what I found when I removed the exhaust manifolds off my '51.... Untitled by Travis Brown, on Flickr It's been 20 years since I've been into a Flathead. I knew it required 4- 7/16 bolts. With that said said, you have a tendency to go back with what came off it. All the bolts and studs that came off the block were 3/8. Since 3/8 is all that came off, I assumed the 7/16 bolts must be for the crossover assembly......it did not click in my head just yet. The car... Untitled by Travis Brown, on Flickr The engine... 239 Ford Flathead. by Travis Brown, on Flickr Not the best photo and as you can see I've got a lot to correct and clean up. I got the engine running well after a tune up but the oil filter was missing. I decide to use the filter off of my spare engine. I ran it in my '50 Coupe 20 years ago. I thought it best to remove the crossover exhaust manifold assembly to install the oil filter. Since I was removing the manifolds I decided to go back with headers as I had kept a set off of my '50 Coupe. Since I'm in Alabama, I thought it best to do away with the crossover under the radiator. It' cant be good for cooling. I actually had three headers. 2 lefts and 1 right. Where the extra left header come from.....I have not a clue. It was in my junk stash. Untitled by Travis Brown, on Flickr I visited the local muffler shop and had him weld up some leaks where the welder could not reach when it was in my '50. The pipes are solid and really, are almost like new. Untitled by Travis Brown, on Flickr I've read on forums where people talk about...."throwing on a set of headers" or....."Yeah, I threw on a set of headers". This suggests that putting a set of headers on is easy-peasy. In reality, it's always been a pain in my butt to add headers to an engine, any engine. Putting headers on a Shoebox with the engine in the car is hard manual labor. I don't have a lift so I'm working under the car. I discoverer I need at least two more elbows, a couple of more wrists and few extra knuckles in my fingers. Since that's not an option....I have to contort under the car in all kinds of strange positions to get my hands where they need to be. I have confined space rescue training and I'll be honest....it helps. I had to stretch one arm straight up close to the firewall twist and bring it back down. You have to get into all types of positions. Both headers will come in from the rear. It is possible to come in from the front ( front air dam has to be removed...it has to be removed any way). You'll find the headers have to be turned just right...at the right time, at the right angle.....it's a lot of twisting and turning. The drivers side.....front end of the headers up past the master cylinder...twist for flange clearance.....front up nearly straight up......twist...front down.....it gets hung on the wiring....(BTW remove the battery, you have got too anyway for clearance...) It tries to hang up on the dip stick (remove it) finally it's in place. This was a dry fit..... Gaskets.... I considered just using high temp RTV. Dry fitting showed me rather quickly that I need to glue the gaskets to the headers themselves. If not, that stuff would have been smeared everywhere except where it needs to be.....the flanges. Glue the gaskets on the headers. Actually I would have preferred the old green/brown Permatex form a gasket....(That stuff smells like Hot Rods)...Instead I use the RTV to glue the gaskets on the headers. I scraped the block flanges clean with a razor knife blade. Wear some glasses. Unbolting and removing the manifolds/crossover was a snap but I did learn that there are some bolts that cannot be reached with an open end wrench.... No matter a socket will do. I have my gaskets glued onto the headers. I have my flanges scraped and cleaned. I have all my 3/8 bolts ready. It's time to put that drivers side on for real now. I do all that contorting again and get the drivers header back into position. I'm going to do the back bolts first, then the middle....and finally the front. The stinking oil filter line is right in the way of starting the front bolt on the rear flange. It takes both hands, using the fore fingers from each hand on each side of the bolt to start it. It's tricky...it can be done. The middle flange.... I can start form the bottom...... The front flange I start from the top and under the front bumper. I'm using 7/16 headed, 3/8 header bolts so I do have wrench clearance against the pipe curve.... By the way, remember when I said a wrench cannot reach them all but a socket can?...Well, a socket does not work on some tube header locations due to pipe curve...only a wrench will work and you have to find that spot..... I start bringing them down. I'm on the last flange...the front. I hand tighten the bottom front flange bolt down and I'm going to fully tighten the top flange bolt. I'm getting it tight....... Then It gives.... Crossed It's all over except for the crying. I walk away from it for a while. And then..........It clicks in my head!!! Flathead V8 exhaust flanges require 4- 7/16 bolts and 8-3/8 bolts. The 4-7/16 bolts are for the font flanges.....the middle and rear exhaust flanges use 3/8 bolts.....The Previous owner had used the WRONG sized bolts on the front...3/8 instead of the correct 7/16 size for the front. The thing is......the 3/8 bolts will actually tighten up a little in the 7/16 hole. This is why he used these on the front..... Untitled by Travis Brown, on Flickr The 3/8 studs in a 7/16 hole kinda sorta worked.....a farmer's repair. I try the 7/16 bolts in my extra engine. They start and screw in fine. Whew! this may work. I try to start the correct bolts in that front header flange. No go! I try to start the 7/16 bolt in the rest of the 7/16 flange holes. Again, no go on them as well. I know better than try to force it. The wrong 3/8 bolts have damaged the 7/16 threads but those threads may still be repairable. Thread Repair... Bad things can happen when using a tap as a chase. A tap can destroy threads if it's started wrong. Not wanting to risk that I made this. Untitled by Travis Brown, on Flickr I took a 7/16 bolt and ground in a taper like a tap. Untitled by Travis Brown, on Flickr I took my dremel and cut flutes to catch debris, old sealer, rust and trash. I try my new little tool in the damaged holes...It wants to start better but really it's still a no go. I'm going to have to use a tap after all. Incidentally walking by the car I notice this.... Untitled by Travis Brown, on Flickr Bingo! That the front and center exhaust that's so hard to reach from underneath or up under the hood .....I have another access point through the wheel well above the wheel. This was really a game changer. It made the very difficult less difficult; still not easy, but less difficult. The car was up, frame on jackstands on each side with the front suspension extended. I have to use my tap. My tap wrench will not fit. My tapered clean out bolt will not start. A tapered tap is the only thing that will work. Untitled by Travis Brown, on Flickr I can't stress enough the care and patience required here. I put a little dab of axle grease on the end of the tap. I start the tap by hand only. I go backward and ease it forward. I repeat. Each time it goes forward it takes a slightly bigger bite. By feel I'm confident the tap is started. By looks I can tell the tap is straight...or least it looks straight. With the 1/4" wrench ( a tap wrench will not fit) I start it ....back and fourth...back and fourth.... real easy. When I'm done with tap. I go to my little bolt tool. I work it in each hole....back and fourth back and fourth. Lastly I use a 7/16 bolt back and fourth...back and fourth just like the tap and just like the bolt tool. Untitled by Travis Brown, on Flickr I work the bolt tool and the bolt until I can easily start it and run it down by hand. I clean the bolt tool flutes often and run it until it's clean. The good news is there's not that much metal that came out of the holes..... Mostly, it's trash and old sealer. Those front studs were glued in with sealer. The last one was a challenge. It does not matter if all the others clean up. If the last one does not clean up, the engine will have to come out for proper thread repair. That last front flange bolt hole, the drivers top front required "extra work" as it by far was the most damaged. Absolutely No Go with the tap! The tap wanted to go crooked. I knew if I tried to start it...Tried to force the tap, it would break or at the least, eat up the threads that were still good. Remembering all the history stuff about old methods, Precision from Imprecision...I looked through my limited tools and used these.... Untitled by Travis Brown, on Flickr A counter sink and a small round file. If I can use the counter sink kind of like a little reamer I might can take the bur off of threads. The end of the hole may act as a funnel for starting the bolt on the good threads. Basically sacrificing off the first few and most damaged threads. Maybe this will give enough that the bolt will start. I only turn the counter sink by hand only, just by finger power....Power tools get you in to trouble, you have no feel. Besides no power anything would fit in there. It was difficult enough just getting my hands in there. I work the sink....back and fourth...back and fourth. I try the tap..still no go. I go back to counter sink. Try the tap..no go. I go to the round file. Around and around in and out in and out just on the edge of the top starting threads. I go back to the tap. It will only turn easily.....back wards. Then I go to my little hero.....the bolt tool. The little bolt tool I made out of a 7/16 bolt...... He starts right in and I can feel that butter smooth full thread engagement. It goes right down.... Untitled by Travis Brown, on Flickr Next I use a 7/16 bolt and it goes right down and starts like nothing was ever damaged. All of these 7/16 bolt locations will tighten properly. Untitled by Travis Brown, on Flickr The threads are repaired. A shop will not do this type of work..... they don't have the time or the inclination. Stuff like this is something only you can do. I was fortunate. Sometimes it just does not work out. This time it did. Headers Round 2.... All that sliding around can move the gaskets. Since the RTV has set up, I make sure all the holes are in perfect alignment. I made sure the gaskets were not going to obstuct the bolts possibly causing a cross thread. by Travis Brown, on Flickr The header is fished back into position with all the difficulty of the previous tries including the dry fit. The spot over the wheel makes it easy. Top bolt; the one of most concern started. Untitled by Travis Brown, on Flickr That last front bottom bolt.....it all had to be done by feel. I went in under the bumper.....I had to hug the crossmember. My right hand with the wrench coming in against the block and my left hand on the bolt, guiding the wrench into position. After nearly each turn, I'd flip the wrench. I would get maybe an 8th to a 4th of a turn. All of this was done totally by feel.... Untitled by Travis Brown, on Flickr That's just headers. I still have to do the passenger side. With the starter off, no steering gear, a straighter header and significantly more room, that should be the easy side. Hopefully.