All three ports need to be flat and level with each other. A buddy of mine used a large belt-sander to level mine when we ported my manifolds.
I figured as much but want to certain. I was thinking going the same route with the belt-sander as well. Harbor Fright has on for $75 but I don't think it has enough HP to get the job done.
Originally posted by str8maxn: I figured as much but want to certain. I was thinking going the same route with the belt-sander as well. Harbor Fright has on for $75 but I don't think it has enough HP to get the job done.
Do you what grit was used?
I used this sander to do mine, I had to remove the tool rest or the flange wouldn't lay flat.
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
ericjon262 --- what Grit did you use for the process?
120 I think... maybe 80? whatever came with the sander.
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
Heck, I used a very large, coarse hand file to even mine out and then some 220 emery cloth to make it a bit smoother, then a couple of coats of VHT high temp paint.
Been on the car 5 years with no leaks.
[This message has been edited by RayOtton (edited 01-29-2021).]
I have heard comments in here that porting can weaken the welds from the flange to the pipe itself and lead to cracking of the welds, resulting in an exhaust leak. I am in the same mode right now. I have a manifold in a vice, getting ready to open up the ports with a die grinder. I have been holding off because I have had other things come up. After reading in here about the weld cracking, I was going to ask if this is just one case or if it is a common thing. Anyone have an opinion/experience on this?
I have a manifold in a vice, getting ready to open up the ports with a die grinder. After reading in here about the weld cracking, I was going to ask if this is just one case or if it is a common thing. Anyone have an opinion/experience on this?
If I were you (or anybody else about to port their exhaust manifolds), I'd forget about using a die grinder.
My buddy has a Hole Saw kit (similar to what's pictured below) which includes a cutter which is the exact same size as the inside of the manifold ports.
...it takes about ten seconds per port to do a perfect job! I'm not kidding. I'm surprised more people don't use this method.
[This message has been edited by Patrick (edited 01-31-2021).]
I'm about to embark on that very situation but I've also noticed through the years the consistency of the legendary front exhaust manifold cracks on the 85-87 V6s.
First, the root cause of the crack ONLY being on the front at the first first flanges is because (I believe) of a weakened or broken Tranny mount and the weakening of the torque strut (aka the Dogbone). Running the engine with these weak points can easily see the engine twisting point is right at the front exhaust manifolds where the Y-pipe joins. Any replacement of the manifolds should have these two points addressed first or the exercise will be repeated, ported or un-ported. I'm going to a urethane tyranny mount and torque strut to solid up this configuration.
The twist is, that its my 88 Formula that is having the ticking noise and based on past experience, I've taken into consideration of having to replace the Y-pipe due to cracking. 88's are the only one with the "Baked Potato" shield and concern has been made over the amount of moisture, over the long run, the Y-pipe cracks at the Y-welds along with the mount situation. Pre-88 Y-pipes are not the same length. I've taken into consideration removing the shielding and going to the pre-88 Y-pipe shielding. The lack of an air pump to the coil in 88s concerns me and I may fabricate additional layers of shielding or maybe relocation. We shall see. I'll be posting a question to the collective mind to see how many 88s took off the heat shield.
If I'm lucky on the 88, I will only have to replace the Y-pipe and I can continue on with the exhaust upgrades (spintech muffler, 2" maybe 2.5 inch exhaust). If the manifold has to be replaced, I'll have a set prepared and ported. Ported exhaust manifolds yield impressive throttle response, I would recommend it.
88's are the only one with the "Baked Potato" shield and concern has been made over the amount of moisture, over the long run, the Y-pipe cracks at the Y-welds along with the mount situation. Pre-88 Y-pipes are not the same length. I've taken into consideration removing the shielding and going to the pre-88 Y-pipe shielding. The lack of an air pump to the coil in 88s concerns me and I may fabricate additional layers of shielding or maybe relocation. We shall see. I'll be posting a question to the collective mind to see how many 88s took off the heat shield.
I've had my '88 Formula for eight years now, always parked outside (and we get a lot of rain here), and so far no problems with the Y-pipe cracking. When I ported my exhaust manifolds, I would've also liked to have done the modification to the Y-pipe, but eventually decided against it as I didn't wish to disturb/wreck the "Baked Potato" shield.
Are you drilling with a 29MM (1 1/8") hole saw all the way thru? down into the long pipe?
I've pickup a Milwaukee hole saw and was not able to punch thru before the teeth were gone.
Porting of my manifolds was done 7-8 years ago, so details are getting a little vague, but... When I acquired my Formula, it required a lot of work (including a clutch replacement), so I had the car towed to a friend's garage which had a lift. We decided to port the exhaust manifolds while we had easy access, and it was a hole saw kit that my buddy actually owned which was used.
All I recall from the process was that the particular hole saw we used fit the inside diameter of the port perfectly... and yes... I admit to being rather surprised myself that the hole saw chewed through the "blockage" in the manifolds so easily. Perhaps there is a difference in quality of hole saws. Maybe some are only designed for use with wood. All I can say is that whatever it was we used had absolutely no problem cutting through metal.
a 1" hole saw can be used to cut thru the blockage. It slides thru the exhaust port and Cuts right thru with little effort. Just be careful that the drill bit does doesn't drill thru the bottom.
Porting of my manifolds was done 7-8 years ago, so details are getting a little vague, but... When I acquired my Formula, it required a lot of work (including a clutch replacement), so I had the car towed to a friend's garage which had a lift. We decided to port the exhaust manifolds while we had easy access, and it was a hole saw kit that my buddy actually owned which was used.
All I recall from the process was that the particular hole saw we used fit the inside diameter of the port perfectly... and yes... I admit to being rather surprised myself that the hole saw chewed through the "blockage" in the manifolds so easily. Perhaps there is a difference in quality of hole saws. Maybe some are only designed for use with wood. All I can say is that whatever it was we used had absolutely no problem cutting through metal.
Bimetal holesaws tend to do a much better job on metal than the cheapies.
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
Can't speak to the specific task, but in general, cutting metal, especially something like cast iron: yes, bi-metal holesaw, not those made for wood, yes, going slow with breaks to keep the teeth cool, and also, use cutting oil. There's a bazillion kinds; I like Sprayon LU208 and Rapid Tap, the latter being more viscous and might work better here.
Bimetal holesaws tend to do a much better job on metal than the cheapies.
quote
Originally posted by dremu:
...in general, cutting metal, especially something like cast iron: yes, bi-metal holesaw, not those made for wood.
Out of curiosity, I contacted my buddy a few minutes ago and asked him what was it about his hole saw that allowed it to cut through the blockage in the exhaust ports so easily... and yes... bi-metal was his response!
Funny you should mention this, because I was looking into this exact thing. I was in Harbor Freight the other day and saw one of these kits and it crossed my mind that I should check into using something like this for the job. A die grinder would take much longer. Thanks for bringing this up. If I do this, this way, I will let you know how it went.
Maybe this will help.. I am a visual person. 1 1/8 " vs. 1" Hole Saw
In the post of mine that I linked to from seven years ago, I stated that we had used a hole saw "which is the exact same size as the inside of the manifold ports".
What we weren't doing was hogging out the exhaust manifold ports to be equal in size to the openings in the exhaust gaskets.
Perhaps this is where some of the apparent confusion comes from in regards to the size of hole saw required for the task.
This photo taken from an old porting thread shows the factory restrictions which we were targeting for removal.
It's the hogging out of the ports to match the gaskets which is what's probably responsible for the flanges often needing to be re-welded. Limiting the porting to just removing the internal restrictions doesn't seem to create this issue... and it's a heck of a lot less work.
Weld around the outside of each of the ports BEFORE porting to avoid the cracking problem. The reason is that some little balls of metal will form on the inside of the manifold. If you port first, then weld, you end up doing the job twice. (Ask me how I know).
BTW, I made a fixture to bolt the manifold to which kept the manifold from warping during the welding operation.
I used a Dremel tool for the job. First I used a milling bit to rough out the hole and then I doubled up cutting disks for polishing. Purely by coincidence the disks were the perfect diameter too.
It takes dedication though, that manifold steel is TOUGH. Went though probably 30 disks for the whole job. You can buy them in packs of 100 for a reasonable price on Amazon.
Is the general concensus that if one uses a 1" hole saw to cut out the obstructions, the reinforcing outside welds are unnecessary? i.e. That post-hole-saw cut strength is no worse than pre-hole-saw cut strength?
Heck, I used a very large, coarse hand file to even mine out and then some 220 emery cloth to make it a bit smoother, then a couple of coats of VHT high temp paint.
