Exhaust Manifolds (Page 1/3)
str8maxn JAN 26, 04:23 PM
Hello all,

I purchased a set stock exhaust manifolds , I am in the process of porting.

I have a question; Do all three ports lay flat and level across all three ports?

I currently have a gap between ports.
Patrick JAN 26, 05:44 PM

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.
str8maxn JAN 26, 05:57 PM

quote
Originally posted by Patrick:


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.

Do you what grit was used?
ericjon262 JAN 26, 06:10 PM

quote
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.

https://www.harborfreight.c...sc-sander-61750.html

------------------
"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."

cognita semper

str8maxn JAN 26, 06:52 PM
ericjon262 --- what Grit did you use for the process?
ericjon262 JAN 26, 09:29 PM

quote
Originally posted by str8maxn:

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."

cognita semper

RayOtton JAN 29, 11:15 AM
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).]

eti engineer JAN 31, 09:57 AM
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?
Patrick JAN 31, 03:06 PM

quote
Originally posted by eti engineer:

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.


quote
Originally posted by Patrick Here:

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).]

WKDFIRO JAN 31, 03:17 PM
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.