What temp does the exhaust run at?

[thedaddycat]

I was looking about in the garage, reading cans and letting my mind do some creative "free association"...... in other works just letting my mind drift. I came across the can of Alvin's Lab-Metal that I had used to repair the gas tank for the Putt Putt. Well guess what they make besides the Lab Metal? Hi-Temp Lab Metal!! Now I know I've seen folks ask about fixing the threads where the muffler screws into the block. This stuff is supposed to be able to handle up to 1000 F temps once properly cured. Is that high enough to withstand the heat at the muffler threads??? If this stuff will work, imagine how many old CI singles have a shot at new life...... Here's the link.... http://www.alvinproducts.com/Products/Products.asp?id=2

[rjgoth]

Hey good question D-Kat :) I believe that the exhaust temps do go in excess of 1000 deg, I think they are in the 1300 -1500 deg. range. I wonder if you could put some of that stuff on an old muffler bolted onto an engine, then run the engine up to temperature to see what happens to it. Sounds like some useful stuff that a guy should have around tho.

[Roy]

Being as pipe threads are tapered they can be cleaned up/recut without going too much deeper into the block. Problem is getting your hands on a 3/4" or 1" pipe tap. They are expensive.

[DaleC]

I borrowed a 1" tap and "cleaned up" the threads on my 12hp and so far have had no problem. It will make screwing the new pipe in a lot easier also.

[MPH]

We have a few welders here, What temp does metal turn red at..My pipe sure gets red blowing snow at nite..MPH

[rjgoth]

A correction to my statement. 1500 deg would be an extreme temp with the engine under heavy load. About 300 to 400 degrees at idle and about 500 to 900 under nomal operating conditions. Mild steel typically will glow at around 1100 degrees.

[thedaddycat]

I have the tap, I was after an easy repair that anyone here could do.... I'm sure that the exhause gasses are a lot hotter than the metal in that area of the block. The muffler also lacks the thermal mass of the cast iron, which also has cooling fins cast into it and a flywheel blowing air across it. I've yet to see the BLOCK turn cherry red even if the muffler reaches incandescent heat. It's still kind of iffy though....

[Al]

Hi, As I remember from an old blacksmith handbood I have, I believe that iron starts to turn red between 500 and 600 degrees. You need to be in a dark area to see it as it starts to turn. There color / temp bands from shiny to blue to straw, to red, to yellow, to white. I think bright red is in the 700 range. I believe the exhaust gas temps are in the 1100 to 1500 ranges, depending on how lean the mixture is and the volume and port capacity. Also the voulumetric efficiency of the engine comes into play here. The block wicks away and disipates the heat around the outside of the port, and the higher temps will be near the center of the ports. I would expect the Block temps near the ports where the muffler connects and contacts the outside air, to be in the 400 500 degree range. My 2 cents worth and its free. Value accordingly. Al Eden

[thedaddycat]

Al, I think you're mixing temper colors with incandescent colors. I couldn't find my blacksmithing books right off either.......

[Al]

Hi, You are correct, but until the reds start they don't glow, do you agree with that? AL

[thedaddycat]

Yep, the pale yellows, straws, blues, right on up to grey are all oxidation colors that indicate tempering heat after the quench. The dull red is the lowest incandescent heat, all the way up to where you let the sparks out of the iron.......

[HubbardRA]

Kirk, The pipe outside the block actually gets hotter than the block because of the large amount of thermal mass in the block. The paints that they make for exhast headers for race cars are goo to 1200F. I am guessing the 1000F material would work in the block. I would try it if I had that problem. Coat the threads and re-tap.

[Salthart]

Anyone ever had a welder repair the exhaust area with a MIG and Phospher Bronze ? Has done well for me in the past.

[BigSix]

I believe that combustion gases inside the engine can exceed 2,200 F. However, I'm betting it will work, due to the block acting as a heat sink, as was mentioned. Perhaps some could be applied to the outside of the threaded area of the block, immediately next to the pipe, and tested that way?

[rjgoth]

Give it a shot D-Kat, let us know how it works. Like you said if you find that this works out as a good repair for damaged exhaust threads, that would be a huge help for lots of folks with old cast iron engines that have damaged exhaust threads. Let us know how it works. If it does work tell us your secret. Good luck, Ryan

[thedaddycat]

Marty, give me the details on the phosphor bronze. What wire size is it, flux core or solid wire, will it work with straight CO2? How about the block? Preheat the cast block, to what temp, any other special considerations? The threads on the 2012 are looking a little on the thin side, I was thinking of what Rod had said. It would be more to give what's there a little back-up "meat", before it becomes a problem.........

[HubbardRA]

If you have an oxy-acetylene outfit, you can always braze the thread area and then re-tap. This is easier on the block material than welding. I've seen many brazed exhaust pipes.