Header- aluminum pan distance.
 

I have been jumping through hoops getting the Mad Dog race headers to fit my GTO. They are 3 piece so its a little like a jigsaw puzzle getting them on the car.
Nice headers though. They way the tubes are is a much straighter shot than my Hookers.
I sent the passenger side back to have a tube moved outward that interfered with my aluminum pan with big kickout.
I get them back and they still hit the sump when I bolt the middle section on without slip fit collector .
But fortunately when I get the collector on it pulls over the # 4 tube to the passenger side enough so it missed the pan by a whole .025 !!
So it looks like a have to massage a small section of header tube. Make a little flat spot for more clearance.
I am thinking a 1/4" gap between the header tube and aluminum sump will be enough as to not effect the integrity of the aluminum oil pan heat wise.

Sound about right ?

I do not want to dent the tube so much. Can not see why a small dent 1/4" deep will effect anything flow wise.
My Hookers have all sorts of dents in the tubes from the factory.

Sounds right.

A little flat or dent in the pipe will affect nothing.

Saw a set of either 1-7/8” or 2” headers on Joel Larkin’s ‘68 Firebird bracket car. One of the pipes closest to the steering box coming right out of the head was bashed in to about half its size. Kinda shocked when I saw that. Anyone who owns one of these cars knows how there’s almost no room there next to the steering box.

Didn’t stop him from running high-9s / low-10s with his ported #12 heads on a 400 (no stroker crank) with that car. He was running a Warrior intake topped by a Dominator carb, this was back in the mid-1990s.

I ran a set of Appliance brand headers on a everyday street motor with one mismade tube touching my steel pan for for two years before I got around to doing anything about it.
I don’t see a need for bending things a full .250” , having it not touch so vibration will not chew through the Aluminum pan is good enough.

I would go for 1/2 that .250” and call it a day .

What would happen clearance wise if you simply just doubled up on the gaskets ?

This is with no gaskets at all. I will gain about 1/2 the thickness of the gasket for clearance. I have some Remflex and they are thick but fragile. The way I have to wrestle the headers I am not sure all of them would survive. They might.
I have some old copper header gaskets and a header plate I made out of 1/4" x 3" flat bar and used a gasket to locate the bolts hole I tapped for 3/8 threads.
I was thinking about red RTVing the copper gaskets to the headers after I clean them up and bolt them to my plate and let dry overnight. Then put some Fel Pro Race header gaskets on the other side effectively doubling my gaskets.
Never have tried anything like this.
I made the plate out of flat bar so when I work on the headers they will be in the same location they are in while in the car. 4 piece headers after all.
I am welding in some O2 sensor bungs on the merge collectors tonight. As well as bungs for a header Evac system if I ever chose to use it. Just need it done before powder coating.
Running a V pump so the EVac bungs will have plugs in them for now.

I would be surprised if the header touching the pan hurt the pan. Heads can be made of aluminum.

Engine masters did a header test and the dented almost every inch of the pipe with no power reduction to my memory

https://www.dailymotion.com/video/x3vupq0

For me the bigger concern would be the amount of heat transfered from the exhaust header to the oil. Touching obviously would make a hot spot inside the oil pan that surely over time create a spot of burnt oil on the inside of the pan.

How much clearance is needed to prevent unwanted heat transfer to the oil? I don't know that number but I'm sure it's been tested and the numbers are out there.

This same concern applies to starters and brake lines.

I put a simple heat shield between the header tube and the oil pan. shiny side out.
Clamped it on with a clamp at the time but later a single tack weld kept it in the right spot.

Worked like a charm as far as keeping the oil colder in the oil pan.

Same concept works well with the oil starter solenoid heat shields. Shield and just a bit of an air gap. Food for thought for your question VCho455.

Tom V.

After you 'bang on' the headers ceramic coating is an excellent thermal barrier.


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I am trying to avoid banging on my headers. With all the money, time and effort on these things. they really are a nice set of headers. But if I have to flatten one small spot 1/4" I will.
But I bet if I can get 1/8" of clearance with gaskets the coating does take away a lot of heat by itself and might be enough.

Its not so much the heat as not having enough clearance, and the thing rattling hitting the pan, especially under the load.

Mid plate, elephant ears. Engine does not move.

I bet the only thing that will happen is a slight discoloration inside the pan in that area from heated oil

remember when that tube is at its hottest point the car will be going over 100 mph and oil will be circulating past the area

Yep, I've had headers run literally an 1/8" from the oil pan and I never gave it a second thought. No big deal, ran those engines for years. Still have at least one maybe 2 here I know is still like that. I never once worried about heating oil and highly doubt it's even an issue. In fact the 1 5/8 headers on the bug are practically a hair away from the oil filter lines and up against the oversize oil pump and that engine has been running for decades, and that's an air cooled engine. Technically that would be more concerning but it's never posed a problem and oil temps are normal (has oil temp gauge)
Dad's 571 Pontiac has 2" headers with a couple tubes right next to the oil pan. Those headers have been on there for 20+ years. It's fine.
If I remember right the hooker headers I've had for V8 Vegas I ran actually touched the moroso deep pan I used and that was my daily for years. Getting ready to use that stuff again on a current build.

Troy,
I am guessing you are checking this cold. I also don't know how much it will change when hot. But an alum engine will see a change of .006" to 0.010" in valve lash from cold to hot.

Stan

I would run a few wraps of quality header wrap right near the pan, just for peace of mind. Reduces heat significantly and might act as a cushion should things move around a bit and .250 becomes .0025.


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I mocked it up today with a set of copper header gaskets, and it touched the pan. Kinda strange, it should have given me a little bit more clearance.
Just going to have to bite the bullet, I mean ball peen hammer and give myself 1/4" clearance and be done with it.
No one will see it anyway.

do a good job of marking off the area and instead of hitting it with a hammer use a deep well socket or similar hard shape, put that on the tube and knock in a small crease, the size of a 9/16 - 5/8 socket probably will do it and it will look better and be more smoothe contour than a obvious hammer strike

Do you know anyone with a mill? I have milled headers flanges, would not need to take too much off to mill the flange at an angle. If you took .03 off the top edge of the flange, that would give .19 at the pan. That is figuring a 2.5" flange being 16" up from the pan.

We have several mills at work. I have thought about doing that. But you would need to do it to all that flanges. Might be a can of worms, all the tubes would go outward. And they are all separate. Could touch something going outward somewhere on some tube. # 8 goes straight out through the inner fender after I cut a hole and wraps around the frame and meets the other 3 tubes for the slip collector. So one change might cause me more trouble.
I even thought about cutting off that center flange and making a new one out of 1/2" flat bar. Setting it all up and bolting the flange to the head and tack weld it. Then disassemble them and fully weld it.
But I am pretty close right now. Just slightly flatten one spot and get it over with.
I need to get this car out to the track. Want at least 2 months of racing. Jones,ing real bad. Need to watch those lights drop and get thrown back in the seat. Smell of burning rubber and checking out all the cars.
Might have to wait until after the season to get them powder coated. Cam is getting re done as we speak so I have to deal with degreeing it in the car, uggh.

Don’t overthink it.

Get out a big hammer with a flat face (not a ball peen) and carefully work that tube flat to gain that 1/4” of clearance and be done with it.

You’re not gonna obstruct the exhaust gas flow on that tube any appreciable amount.

Git ‘er done.