Gerry
Well-Known Member
Hi
As a few of you out there have mentioned about the lack of posts in the technical section I thought I would cover the making of my 8 pipe headers. I am writing this in a way that someone who has never done something like this is going to be able to follow, so please do not take offensive if it seems like I am trying to teach my Granny to suck eggs. I am also sure that my methods may not be the way you do things so please feel free to add any constructive comments that may help someone who is thinking of tackling something like this for the first time.
I don’t know if I have the stamina to do this in one go but let’s start anyway.
We will cover the following:
1. Planning and visuals
2. Making the flanges
3. Mock up
4. First fix
5. Getting them on.
6. Cleaning up
7. Brackets and mounts.
Step 1
I always wanted a set of 8 pipe headers in the fashion of the 70s fads. I mocked up a 4 into one and a bunched 4 but nothing looks as good to me as 4 pipes running down the side of a T.
The first thing I did was to take some pictures. You can do this by taking a photograph (either digital or film) and making 10 copies of it. Now get out your pens, pencils, felt tip… whatever and start drawing the headers you want on the pictures. I did this both on copies of a digital print and on a photo touchup software package I have. I tried a few different layouts to see which I preferred. You do NOT have to be good at drawing to do this. Just start putting pen to picture and if it don’t work, start again. That’s the reason for the 10 copies. In the past I have gone through dozens of copies just doodling and playing around with ideas. Its amazing how many variations you can come up with, THIS IS HOW NEW THINGS GET DISCOVERED so give it a try.
First sketch was with the pipes running parallel to the ground, then with them running parallel to the body. I decided on the second on as it made the whole thing look designed as opposed to ‘hung together, The funny thing is to this day the first choice still appeals to me.
Once you have got the look you want you can start getting the material and parts. For me this was 16 bits of 2’’ stainless steel pipe each with a 90 degree bend. I will explain later why I did it this way, but I started with the flanges.
The original designed called for lots of pipes on the car. That is the ram tubes and exhausts which tend to flow from the top of the motor, thro it and out to the exhausts. With the ram tubes being 2’’ diameter the exhausts HAD to be the same.
Now as you 350 Chevy guys will know the middle two ports will not take two 2’’ diameter pipes without either scolloping them out for the header studs or flattening them where they meet in the middle. I did not want either of these options so came up with a double flange idea. It may have been done before but I had not seen it.
Step 2.
I got a thick piece of paper and held it against the port on the head, then with a pencil drew the shape of the flange by rubbing the paper against the edge of the machine surface of the port. Likewise a press with a finger over the holes produces a nice round mark. This gives a copy of the flange shape on paper. I would like to say at this point that I could not get dimensions for the D port heads anywhere, but I am sure one of our sponsors probably has these on file, so call them first to see if you can save this and the next few steps. At this point its worth checking the flanges to make sure they are the same on both heads. I ended up with 3 sketches. One for the front port, one for the middle port and one for the rear port. As you would expect the other head was exactly the same but believe me its worth checking.
I then scanned the sketches in to a drawing software package that I have been using for years. Once saved as a file, I ‘normalised’ each sketch to make sure the corners were all the same radius and the edges were straight. These files are the base for the flanges that will bolt to the heads (inner flanges) and the flanges that will carry the header pipes (outer flanges)
With the inner flanges being just the same as the sketches there is nothing more to do on these except save a copy under a new name for the outer flange drawing. This is because the outline of the two will be the same.
Using the copy of the inner flange drawing I changed the D port hole to a 2’’ diameter hole which will take the header tubes and deleted the two holes for the header studs. The outer flanges will bolt to the inner ones using short bolts (take a look at the picture to see what I mean if I have confused you). Both of these files were then saved in the drawing file type and as a DFx file which can be read by a Cad system. I also ordered and extra one of each in case of any mistakes or problems. Its cheaper to do this now than have to go back to the laser company and get a couple of extras at a later date
This file was then emailed to a laser cutting company who made them out of 8mm (3/8) stainless steel.
Ok so you have the flanges in your hands. The inner flanges have a cut out for a D port and two holes for the header studs, We are NOT going to use studs but hidden bolts to fix these inner flanges to the heads. The stud holes therefore need countersinking to allow the bolts to be flush with the flange surface. Simple task to countersink all the mounting holes in the inner flange set.
With this done take one inner flange and one outer flange and clamp them together so that all the edges line up. Should be a perfect fit as they came from the same original drawing.
Once clamped drill the holes for the bolts which will fix the two flanges together. I ALWAYS use a smaller drill than the tapping size for a first hole. In my case I decided on 4 bolts…one in each corner.
Now run through these holes with a tapping size drill for the bolts you are going to use. This done separate the flanges and put the outer ones to one side. Take the inner flanges and tap a thread through all the holes.
Now take the outer flanges and run a clearance size drill through all the holes. Ok so now bolt them all together and make sure it all fits. Takes a bit of time but it will be worth it.
The next step is to bolt the inner flanges to the heads using countersunk bolts. I found that the bolt heads were still too long to go completely flush so a little work with a finishing grinder (2’’ pad and gentle pressure) got them to about the same level. Now work the surface flat and even with a hand file. YEP a HAND file. This should give you a good smooth and level surface for the header gasket to seat against. Spend time on this as a poor surface will haunt you with leaks and black smut everywhere. Once completed screw the outer flanges to the inner ones ready for the pipes to be fitted.
Step 3.
This is in my opinion the MOST important step of all. Time spent here will save hours of work later on, not to mention $.
The critical step is to get the T set level and at the correct ride heights both front and rear. If the car is not set level and at the right height there is NO point in trying to put the headers on. They will never look right from this day on. I cant emphasise the need to measure, measure and measure again. In fact I have got in to the habit of measuring twice, having a coffee or beer and measuring again. It gets things right first time and stops the need to bang your head against the nearest hard surface until it hurts.
OK with the ‘lecture’ out of the way lets start on the pipes. As I mentioned earlier I had the pipes made in two sections each. This is because we wanted to be able to adjust and tweek them to exactly the height, distance and angle we wanted. You could of course make your measurements and have a tube bender make them in one piece, that’s your choice.
Because we were going to join the pipe on the vertical section I dropped in on a local company that makes headers for race cars and got them to cut me 8 sections 2’’ long and sized to the internal diameter of my header pipes. For those of you that are not familiar with pipe companies, they have a machine that can expand a stock diameter pipe to a tight sliding fit in the next size up. This will mean at each join the two sections of header pipes will be held perfectly in line and the welded joint will have a reinforced backing to them. It may be over the top but I don’t want the weld cracking at a later date.
Mocking up involves lots of blocks of wood, metal whatever comes to hand and a certain amount of duck tape. As the pipe section were all over length the mock up has to be done with a bit of imagination, by taping two section together along side each other to get a feel for what looks ok. We actually set up all 4 pipe like this to make sure everything was looking good.
We now had to make a decision on where they should run in relation to the rest of the T. As I mentioned earlier the pipes had to run parallel to the car NOT the ground, so that’s the first step. Block, tape or suspend the pipe(s) so that they follow the line you want. For me this was level with the bottom of the body and at the same angle as the chassis and top of the body from the cowl back. With the side view looking good its time to set the pipe for the angle as viewed from above.
We wanted them to follow the ‘flair’ of the body as it widens from the cowl to the rear. This also gave us an opportunity to decide where they should end near the rear wheels. I wanted them so the inside pipe ended up pointing at the inside edge of the rear tyre, but to keep them inline with the body shape I had to compromise and have the inside pipe half way across the inside tread line. No big deal they ended up within a small distance of where I wanted them and we kept everything in line with the body, chassis and motor lines. This took a few hours of work, 20 feet of duck tape and loads of bits of wood and metal. Time spent here will save a lot of heart ache later on. Once you commit to welding its not easy or cheap to go back and start over.
Step 4
We started by working the hole in one of the outer flanges to accept a length of pipe. As the flanges are not at 90 degrees to the pipes this means the hole has to be worked at the top and bottom to allow the pipe to fit at an angle and allow it to run parallel to the ground. We used a die grinder to do this but a round file works just as well if a little slower. Starting with the inner most pipe to set the distance from the radius rod to the pipe we cut it at approximately the correct length (too long that is) from the heads to the down turn and tried it on the car.
Once this was done we carefully trimmed it to length (in more than one cut… take off too much here and you will be ordering another length of pipe.) With the distance right its time to tack it in to place. This is the reason we spent so much time on levelling the car. Once in place run a level on top of the pipe and adjust until its exactly at zero degrees. We actually tacked the pipe to the flange on the inside in one place. Then refitted it and adjusted it again. Then took if off and tacked it at 120 degrees from the original tack. Refitted it and check it again before committing to the last tack. You guessed it… we refitted it yet again and checked alignment to the floor (level) alignment to the engine (at 90 degrees) and finally alignment of the vertical section again at 90 degrees to the floor. We now have a starting point to work the other 3 pipes to. It takes a LOT of time but HEY.. you want it right, don’t you?
Here’s a tip from the header company I used for my reinforcing parts. Only weld on one side of the flange. Either inside or outside never both. They told me that welding both sides of the flange sets up stresses and will almost certainly cause the weld to crack out and break. I decided to take their advice as they have made hundreds of custom headers for race cars in both mild and stainless steel.
I think I will leave it there for today as a few hours have passed and I am getting ‘screen crazy’
Gerry
As a few of you out there have mentioned about the lack of posts in the technical section I thought I would cover the making of my 8 pipe headers. I am writing this in a way that someone who has never done something like this is going to be able to follow, so please do not take offensive if it seems like I am trying to teach my Granny to suck eggs. I am also sure that my methods may not be the way you do things so please feel free to add any constructive comments that may help someone who is thinking of tackling something like this for the first time.
I don’t know if I have the stamina to do this in one go but let’s start anyway.
We will cover the following:
1. Planning and visuals
2. Making the flanges
3. Mock up
4. First fix
5. Getting them on.
6. Cleaning up
7. Brackets and mounts.
Step 1
I always wanted a set of 8 pipe headers in the fashion of the 70s fads. I mocked up a 4 into one and a bunched 4 but nothing looks as good to me as 4 pipes running down the side of a T.
The first thing I did was to take some pictures. You can do this by taking a photograph (either digital or film) and making 10 copies of it. Now get out your pens, pencils, felt tip… whatever and start drawing the headers you want on the pictures. I did this both on copies of a digital print and on a photo touchup software package I have. I tried a few different layouts to see which I preferred. You do NOT have to be good at drawing to do this. Just start putting pen to picture and if it don’t work, start again. That’s the reason for the 10 copies. In the past I have gone through dozens of copies just doodling and playing around with ideas. Its amazing how many variations you can come up with, THIS IS HOW NEW THINGS GET DISCOVERED so give it a try.
First sketch was with the pipes running parallel to the ground, then with them running parallel to the body. I decided on the second on as it made the whole thing look designed as opposed to ‘hung together, The funny thing is to this day the first choice still appeals to me.
Once you have got the look you want you can start getting the material and parts. For me this was 16 bits of 2’’ stainless steel pipe each with a 90 degree bend. I will explain later why I did it this way, but I started with the flanges.
The original designed called for lots of pipes on the car. That is the ram tubes and exhausts which tend to flow from the top of the motor, thro it and out to the exhausts. With the ram tubes being 2’’ diameter the exhausts HAD to be the same.
Now as you 350 Chevy guys will know the middle two ports will not take two 2’’ diameter pipes without either scolloping them out for the header studs or flattening them where they meet in the middle. I did not want either of these options so came up with a double flange idea. It may have been done before but I had not seen it.
Step 2.
I got a thick piece of paper and held it against the port on the head, then with a pencil drew the shape of the flange by rubbing the paper against the edge of the machine surface of the port. Likewise a press with a finger over the holes produces a nice round mark. This gives a copy of the flange shape on paper. I would like to say at this point that I could not get dimensions for the D port heads anywhere, but I am sure one of our sponsors probably has these on file, so call them first to see if you can save this and the next few steps. At this point its worth checking the flanges to make sure they are the same on both heads. I ended up with 3 sketches. One for the front port, one for the middle port and one for the rear port. As you would expect the other head was exactly the same but believe me its worth checking.
I then scanned the sketches in to a drawing software package that I have been using for years. Once saved as a file, I ‘normalised’ each sketch to make sure the corners were all the same radius and the edges were straight. These files are the base for the flanges that will bolt to the heads (inner flanges) and the flanges that will carry the header pipes (outer flanges)
With the inner flanges being just the same as the sketches there is nothing more to do on these except save a copy under a new name for the outer flange drawing. This is because the outline of the two will be the same.
Using the copy of the inner flange drawing I changed the D port hole to a 2’’ diameter hole which will take the header tubes and deleted the two holes for the header studs. The outer flanges will bolt to the inner ones using short bolts (take a look at the picture to see what I mean if I have confused you). Both of these files were then saved in the drawing file type and as a DFx file which can be read by a Cad system. I also ordered and extra one of each in case of any mistakes or problems. Its cheaper to do this now than have to go back to the laser company and get a couple of extras at a later date
This file was then emailed to a laser cutting company who made them out of 8mm (3/8) stainless steel.
Ok so you have the flanges in your hands. The inner flanges have a cut out for a D port and two holes for the header studs, We are NOT going to use studs but hidden bolts to fix these inner flanges to the heads. The stud holes therefore need countersinking to allow the bolts to be flush with the flange surface. Simple task to countersink all the mounting holes in the inner flange set.
With this done take one inner flange and one outer flange and clamp them together so that all the edges line up. Should be a perfect fit as they came from the same original drawing.
Once clamped drill the holes for the bolts which will fix the two flanges together. I ALWAYS use a smaller drill than the tapping size for a first hole. In my case I decided on 4 bolts…one in each corner.
Now run through these holes with a tapping size drill for the bolts you are going to use. This done separate the flanges and put the outer ones to one side. Take the inner flanges and tap a thread through all the holes.
Now take the outer flanges and run a clearance size drill through all the holes. Ok so now bolt them all together and make sure it all fits. Takes a bit of time but it will be worth it.
The next step is to bolt the inner flanges to the heads using countersunk bolts. I found that the bolt heads were still too long to go completely flush so a little work with a finishing grinder (2’’ pad and gentle pressure) got them to about the same level. Now work the surface flat and even with a hand file. YEP a HAND file. This should give you a good smooth and level surface for the header gasket to seat against. Spend time on this as a poor surface will haunt you with leaks and black smut everywhere. Once completed screw the outer flanges to the inner ones ready for the pipes to be fitted.
Step 3.
This is in my opinion the MOST important step of all. Time spent here will save hours of work later on, not to mention $.
The critical step is to get the T set level and at the correct ride heights both front and rear. If the car is not set level and at the right height there is NO point in trying to put the headers on. They will never look right from this day on. I cant emphasise the need to measure, measure and measure again. In fact I have got in to the habit of measuring twice, having a coffee or beer and measuring again. It gets things right first time and stops the need to bang your head against the nearest hard surface until it hurts.
OK with the ‘lecture’ out of the way lets start on the pipes. As I mentioned earlier I had the pipes made in two sections each. This is because we wanted to be able to adjust and tweek them to exactly the height, distance and angle we wanted. You could of course make your measurements and have a tube bender make them in one piece, that’s your choice.
Because we were going to join the pipe on the vertical section I dropped in on a local company that makes headers for race cars and got them to cut me 8 sections 2’’ long and sized to the internal diameter of my header pipes. For those of you that are not familiar with pipe companies, they have a machine that can expand a stock diameter pipe to a tight sliding fit in the next size up. This will mean at each join the two sections of header pipes will be held perfectly in line and the welded joint will have a reinforced backing to them. It may be over the top but I don’t want the weld cracking at a later date.
Mocking up involves lots of blocks of wood, metal whatever comes to hand and a certain amount of duck tape. As the pipe section were all over length the mock up has to be done with a bit of imagination, by taping two section together along side each other to get a feel for what looks ok. We actually set up all 4 pipe like this to make sure everything was looking good.
We now had to make a decision on where they should run in relation to the rest of the T. As I mentioned earlier the pipes had to run parallel to the car NOT the ground, so that’s the first step. Block, tape or suspend the pipe(s) so that they follow the line you want. For me this was level with the bottom of the body and at the same angle as the chassis and top of the body from the cowl back. With the side view looking good its time to set the pipe for the angle as viewed from above.
We wanted them to follow the ‘flair’ of the body as it widens from the cowl to the rear. This also gave us an opportunity to decide where they should end near the rear wheels. I wanted them so the inside pipe ended up pointing at the inside edge of the rear tyre, but to keep them inline with the body shape I had to compromise and have the inside pipe half way across the inside tread line. No big deal they ended up within a small distance of where I wanted them and we kept everything in line with the body, chassis and motor lines. This took a few hours of work, 20 feet of duck tape and loads of bits of wood and metal. Time spent here will save a lot of heart ache later on. Once you commit to welding its not easy or cheap to go back and start over.
Step 4
We started by working the hole in one of the outer flanges to accept a length of pipe. As the flanges are not at 90 degrees to the pipes this means the hole has to be worked at the top and bottom to allow the pipe to fit at an angle and allow it to run parallel to the ground. We used a die grinder to do this but a round file works just as well if a little slower. Starting with the inner most pipe to set the distance from the radius rod to the pipe we cut it at approximately the correct length (too long that is) from the heads to the down turn and tried it on the car.
Once this was done we carefully trimmed it to length (in more than one cut… take off too much here and you will be ordering another length of pipe.) With the distance right its time to tack it in to place. This is the reason we spent so much time on levelling the car. Once in place run a level on top of the pipe and adjust until its exactly at zero degrees. We actually tacked the pipe to the flange on the inside in one place. Then refitted it and adjusted it again. Then took if off and tacked it at 120 degrees from the original tack. Refitted it and check it again before committing to the last tack. You guessed it… we refitted it yet again and checked alignment to the floor (level) alignment to the engine (at 90 degrees) and finally alignment of the vertical section again at 90 degrees to the floor. We now have a starting point to work the other 3 pipes to. It takes a LOT of time but HEY.. you want it right, don’t you?
Here’s a tip from the header company I used for my reinforcing parts. Only weld on one side of the flange. Either inside or outside never both. They told me that welding both sides of the flange sets up stresses and will almost certainly cause the weld to crack out and break. I decided to take their advice as they have made hundreds of custom headers for race cars in both mild and stainless steel.
I think I will leave it there for today as a few hours have passed and I am getting ‘screen crazy’
Gerry
