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| Exhaust Manifolds (Page 3/3) |
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str8maxn
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JAN 31, 11:47 PM
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| quote | Originally posted by Patrick:
Okay, you've now confused me. 
[EDIT] I have to assume that you're talking about two different hole saws here, and that the first one was not designed to be used on metal.
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Maybe this will help.. I am a visual person. 1 1/8 " vs. 1" Hole Saw
 [This message has been edited by str8maxn (edited 01-31-2021).]
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Patrick
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FEB 01, 04:24 PM
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| quote | Originally posted by str8maxn:
Maybe this will help.. I am a visual person. 1 1/8 " vs. 1" Hole Saw
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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.
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RayOtton
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FEB 02, 09:00 AM
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As for the welding issue.
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.
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dremu
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FEB 02, 10:13 AM
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str8maxn
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FEB 21, 04:41 PM
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Did I ruin my manifold?
I was grinding the ports true , got distracted and didn't realize I was grinding away the back of the manifold .
Are these still useable?
Is it repair needed? If so, how?
 [This message has been edited by str8maxn (edited 02-21-2021).]
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str8maxn
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MAR 30, 04:32 PM
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| quote | Originally posted by str8maxn:
Did I ruin my manifold?
I was grinding the ports true , got distracted and didn't realize I was grinding away the back of the manifold .
Are these still useable?
Is it repair needed? If so, how?
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After all the work... I will not be using them. I recently purchased another Fiero with a V8 . Thank you all for the help.
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Patrick
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MAR 30, 05:31 PM
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| quote | Originally posted by str8maxn:
After all the work... I will not be using them. I recently purchased another Fiero with a V8.
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Yep, that's definitely another way to solve the problem. 
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reinhart
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APR 02, 07:02 AM
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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?
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