Odd findings

B RON CO

B RON CO

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Hello! This is Peter, B RON CO's son, or B RON CO Jr. I guess you could call me. I read the forum from time to time, (mainly to check that my old man is staying out of trouble :LOL: ), but maybe I'll make an account one of these days!

Anyhow, when I tore off the old exhaust manifold, I found this sort of swelled up/cracked section, and I was kind of curious if anyone else has seen this, as we were quite surprised. It must get pretty hot in there (especially where it swelled since this area flows both the #3 & 4 exhaust ports) so I am certain it is due to some sort of heat/swirl/air flow phenomenon.

I'm a mechanical engineering student at RIT and I probably should have paid more attention in my heat transfer class :unsure: ... but I'm still good friends with the professor (who also happens to play with I6's, but more of the Bavarian kind), so I'll probably ask him too and see what he thinks.

Cheers!
:beer:
-Pete, aka B RON CO Jr.

IMG_20170520_121740.jpg

IMG_20170520_121748.jpg
 
Possibly caused by a lean A/F ratio which crystallized the cast iron due to excessive heat or a buildup of carbon???
 
did some 1 install a 'port divider' & it has 2 much heat/carbon?
 
Howdy Ron Jr:

First off, great job on reviving the Broncs engine bay. It looks great! And Welcome to The Forum.

I've never seen a build up like that. My guess is a combination of bad gas and lots of idling or low rpm use It does how signs of high heat also. very interesting. What is the casting code on the manifold? When you chip away the buildup is the heat transfer tube solid and intact? Was there any buildup in the 3 & 4 exhaust ports in the head?

I'll be anxious to hear what you find.

Adios, David
 
it kind of looks to me like a PO installed a port divider in the manifold, i have an exhaust manifold that will be going on my falcon on hand to reference, and it has a large open port for the three and four cylinders. and this divider was made from inferior material and the result if what you are seeing now.
 
Hey guys, here are some more pictures. You can see through the exhaust manifold outlet:

IMG_20170529_154819.jpg


Any casting numbers are illegible, but chipping away at some of the buildup seems to shows some deeper cracks. The damage appears to go pretty deep, possibly all the way through, but I don't want to cut it up further. I don't think you can call this buildup in the way that carbon builds up, I think this is entirely cast iron that's either swelled and cracked, or maybe crystallized and grown.

Looking into the exhaust port, there is no divider:

IMG_20170529_155340.jpg


The valves and spark plugs on these cylinders look fine, only number 6 was a little burned, it was probably not sealing all the way down at that end as the tab on the head was broken off. But I doubt that would affect the flow at 3 & 4:

IMG_20170529_155305~01.jpg


Thanks guys!

-B RON CO Jr.
 
I think I've figured it out. Here's an article from The Mechanical Engineer, Volume 38 edited by William Henry Fowler. It basically says that as the material is repeatedly heated up to regular operating temperature and cooled, it can expand and crack. As the hot exhaust gases flow past, they are forced into the cracks, and the cracks can widen over time. As gases are forced into these cracks, the material will oxidize, separating the graphite from the iron due to the differences in their thermal expansions. This sounds a lot like what we see! So I suppose this is all just a result of this part being subject to a harsh environment. But it's odd that none of us have seen this before!

castiron.png
 
metallurgy!
leave it ta ford6!
(physics & chemistry over in the HardCore Inline Tech forum)
:shock:
:eek:
:LOL:
 
B RON CO":2ol6zvli said:
I think I've figured it out. Here's an article from The Mechanical Engineer, Volume 38 edited by William Henry Fowler. It basically says that as the material is repeatedly heated up to regular operating temperature and cooled, it can expand and crack. As the hot exhaust gases flow past, they are forced into the cracks, and the cracks can widen over time. As gases are forced into these cracks, the material will oxidize, separating the graphite from the iron due to the differences in their thermal expansions. This sounds a lot like what we see! So I suppose this is all just a result of this part being subject to a harsh environment. But it's odd that none of us have seen this before!

castiron.png
Click to expand...
I agree 100%,...Have seen this before and it is not a rare occurrence.
 
drag-200stang":2ra37cib said:
B RON CO":2ra37cib said:
I think I've figured it out. Here's an article from The Mechanical Engineer, Volume 38 edited by William Henry Fowler. It basically says that as the material is repeatedly heated up to regular operating temperature and cooled, it can expand and crack. As the hot exhaust gases flow past, they are forced into the cracks, and the cracks can widen over time. As gases are forced into these cracks, the material will oxidize, separating the graphite from the iron due to the differences in their thermal expansions. This sounds a lot like what we see! So I suppose this is all just a result of this part being subject to a harsh environment. But it's odd that none of us have seen this before!

castiron.png
Click to expand...
I agree 100%,...Have seen this before and it is not a rare occurrence.
Click to expand...
I think what causes that is a damaged choke heat riser tube , that stops air flow from cooling it, like it should on the way to the choke.
 
Our manifold is an early 170, and the carb has a manual choke. We don't see a hole for the heat riser tube.
[image]https://dl2.pushbulletusercontent.com/KGH1CpCeImocE60b0k5Z0AQheSni9l1j/IMG_20170530_114237.jpg[/image]
 
B RON CO":3m3a2ssl said:
Our manifold is an early 170, and the carb has a manual choke. We don't see a hole for the heat riser tube.
[image]https://dl2.pushbulletusercontent.com/KGH1CpCeImocE60b0k5Z0AQheSni9l1j/IMG_20170530_114237.jpg[/image]
Click to expand...
Well I rest my case, no cooling for that spot. ;) The manifold sure looks to be cast for a choke tube in mind..
I am sure a new one will last a long time with no trouble, forget about it.
 
I used to work at a wrecking yard and I've also seen that phenomenon before, and in other exhaust manifolds besides our sixes too. It always seems to happen where the heat riser tube goes through, so I always figured it had something to do with there being air behind that superheated cast iron, which is thinner walled in that spot than anywhere else. Since your heat riser boss appears to be untapped, I'd be very curious if you cut a section out of that bad spot (if you are tossing it out anyway) to see if it is hollow inside or not.

Scott
 
B RON CO":tgh3z2sj said:
Hello! This is Peter, B RON CO's son, or B RON CO Jr. I guess you could call me. I read the forum from time to time, (mainly to check that my old man is staying out of trouble :LOL: ), but maybe I'll make an account one of these days!

Anyhow, when I tore off the old exhaust manifold, I found this sort of swelled up/cracked section, and I was kind of curious if anyone else has seen this, as we were quite surprised. It must get pretty hot in there (especially where it swelled since this area flows both the #3 & 4 exhaust ports) so I am certain it is due to some sort of heat/swirl/air flow phenomenon.

I'm a mechanical engineering student at RIT and I probably should have paid more attention in my heat transfer class :unsure: ... but I'm still good friends with the professor (who also happens to play with I6's, but more of the Bavarian kind), so I'll probably ask him too and see what he thinks.

Cheers!
:beer:
-Pete, aka B RON CO Jr.

IMG_20170520_121740.jpg

IMG_20170520_121748.jpg
Click to expand...

Hi B RON Co Jr. X3 I have seen this on a few engines over years though don't think on a Ford small six. In my opinion I agree that it's also a sign of a very lean running engine. In any respect that exhaust manifold sure led a very hard life if you still need to use it you could grind the bulging sides straight again and put her back in service. Good luck (y) :nod:
 
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