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Discussion Starter #1
What can I do about this exhaust bolt not fitting correctly. I’m not sure if shaving it some would be a smart idea. See pictures.
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You can either give the tube a little squish on that side, or take a rat tail file /die grinder and carbide burr and taper the entry side of the hole to the outboard side....it won't take much to get enough room for the bolt to slip into place....you'll just have to remember that bolt has to go in either first or with the header still really loose on the bolts so it can be pulled far enough away from the head to allow the bolt room to tilt into the hole.

If needed you can also get header bolts with a 3/8" or 5/16" wrench head instead of the standard header bolt 7/16" head if you need more wrench clearance.

I had two tubes like that on my 1-3/4" SBC Hedmans for '68-74 Nova/'67-69 Camaro...I took a 3/4" diameter piece of thckwall tubing or solid stock and wrapped it with a few layers or electrical tape, then laid the wrapped tube against the side of the header pipe and smacked it with a small 5lb hand sledge hammer to put a nice curved dimple in the tube.....that way it looks like it should be there, rather than like you went postal on it with a framing hammer.
This was with ceramic coating too, you can do small adjustments like this without hurting the coating if you do it prior to running hte headers for the first time....the coating needs exhaust heat for the final cure.
 

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Discussion Starter #3
You can either give the tube a little squish on that side, or take a rat tail file /die grinder and carbide burr and taper the entry side of the hole to the outboard side....it won't take much to get enough room for the bolt to slip into place....you'll just have to remember that bolt has to go in either first or with the header still really loose on the bolts so it can be pulled far enough away from the head to allow the bolt room to tilt into the hole.

If needed you can also get header bolts with a 3/8" or 5/16" wrench head instead of the standard header bolt 7/16" head if you need more wrench clearance.

I had two tubes like that on my 1-3/4" SBC Hedmans for '68-74 Nova/'67-69 Camaro...I took a 3/4" diameter piece of thckwall tubing or solid stock and wrapped it with a few layers or electrical tape, then laid the wrapped tube against the side of the header pipe and smacked it with a small 5lb hand sledge hammer to put a nice curved dimple in the tube.....that way it looks like it should be there, rather than like you went postal on it with a framing hammer.
This was with ceramic coating too, you can do small adjustments like this without hurting the coating if you do it prior to running hte headers for the first time....the coating needs exhaust heat for the final cure.
Nice that really helps, I actually forgot to mention that it had the ceramic coating also. But the method with the other pipe wrapped might be the winner. But if I have to taper the hole,what could I do about that spot that wouldn’t have any of the ceramic coating after I taper it.
 

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I would grind the hole on the flange mounting side with a small carbide burr so the threads clear as slide in. Grind so you create a slide taper to that side of the hole only. You will need to start this screw to the head first when mounting. No evidence of rework once installed.
 

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Step drill half the depth of the hole from the head side or until the bolt slides through. Easy fix.
 

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Discussion Starter #7
I would grind the hole on the flange mounting side with a small carbide burr so the threads clear as slide in. Grind so you create a slide taper to that side of the hole only. You will need to start this screw to the head first when mounting. No evidence of rework once installed.
I know the flange is pretty thick but would that cause an exhaust leak in the future with the taper having to be in the header pipe?
 

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No the gasket seals the rectangle exhaust port the bolt hole has nothing to do with that.
 

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Discussion Starter #9
No the gasket seals the rectangle exhaust port the bolt hole has nothing to do with that.
Well what I mean is by tapering it wouldn’t it thin the area between the header pipe and the bolt hole and create a spot for a possible exhaust leak in the future?
 

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If you get carried away .........yes. Only grind enough to push the bolt thru. If you are concerned you would get too much out then grind a bit off the bolt shoulder too.
 

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I fact maybe just grinding the bolt shoulder where the hex flat is might do it for you.

If this were my project this would be my first attempt. Always go for what seems to be the most straight forward solution. But this would still have to be the first bolt threaded into the cylinder head. You may still be limited to using an open end wrench.
 

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Discussion Starter #13
I fact maybe just grinding the bolt shoulder where the hex flat is might do it for you.

If this were my project this would be my first attempt. Always go for what seems to be the most straight forward solution. But this would still have to be the first bolt threaded into the cylinder head. You may still be limited to using an open end wrench.
okay let’s say I take a little off both sides of the flange to minimize the amount taken off on 1 side. What could I use to protect the area the ceramic would be removed from.
 

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Only one side the side against the head. Not visible once mounted. The shoulder on the bolt would be as I said my first choice to grind down.

Are you familiar with hex socket cap screws? That may assemble with out grinding at all. Head is very small, suggest use a washer with it to spread clamping force.
 

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Looking at your picture, the little bit of grinding you need with a Dremel tool or rotary cutter is almost nothing. You'll never see it until you pull the header off again.
 

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Only one side the side against the head. Not visible once mounted. The shoulder on the bolt would be as I said my first choice to grind down.

Are you familiar with hex socket cap screws? That may assemble with out grinding at all. Head is very small, suggest use a washer with it to spread clamping force.
If you remove material on the head side , you will narrow an already limited area between the bolt & exhaust port , I'd rather see material removed on the frt side rather than compromise gasket sealing ..
 

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If you remove material on the head side , you will narrow an already limited area between the bolt & exhaust port , I'd rather see material removed on the frt side rather than compromise gasket sealing ..
Header paint ..
This would be the way I'd do it to if grinding the hole. If you go easy with the cut, no exposed metal will show when installed, and just touch-up paint to to prevent bare metal from corroding in the hole.
I know with my coated headers the flange see's a lot less heat and the flange coating is still in great shape....the pipes have all gotten rusty after 10 years and need to be sent in and redone. They were from a time when Hedman was coating themselves, the coating was not Jet-Hot or HPC quality.

If you reduce the size of the flange on the bolt, it is going to have a tendency to pull into the hole and collapse the edge of the flange around the hole due to not enough surface contact to spread the load well. I would not suggest doing that, bolt will likely have a tendency to come loose as vibration will constantly be working on it and the edge of the hole will keep deforming and coming loose..
Cutting the hole on one side also reduces bolt face contact, but not around the full diameter like cutting the bolt itself does.

Personally, I"d go for the controlled dent first, get the clearance and not have to cut or grind anything. It won't take much, looks like you barely need .030" more to get it in there.
 

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How about using a hardened washer shaped to fit on the outside to maintain as much gasket surface as possible ..?
 
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