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Old 01-26-2020, 12:39 PM   #21
Jim Brierley
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Default Re: Exhaust port crack.... need help!

Ursus, I would pin it, IF there is enough thickness for the pin to bite into.
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Old 01-26-2020, 12:45 PM   #22
Matts30coupe
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Default Re: Exhaust port crack.... need help!

Thank you to you all that replied, here is my situation. I planned on investing a couple bucks into this motor with cam, head, intake, carb etc, to warm it up a bit. I had a gut feeling do to the antifreeze in my exhaust header that there was a problem... So in a sense this is a blessing in disguise... Id love to find a good motor somewhat local to build. I rather not stress this one out anymore, to me I only see some of these other cracks spreading to areas that will be unable to be stitched.

I am goin to try an experiment, I guess it will be informative for all of us! I picked up a jar of this JB High Temp paste. I etched the surface and applied the product. it says it hold to 2400degs. So ill give it a couple days, blend it in the the cast and resemble the motor back to its stock forum. I will them run the motor on an off for maybe a couple hours and pull of the exhaust manifold and inspect the area.

If it is good then reassemble and run it to inspect it down the road, if its bad then i will be looking for a good A block to build up. Or who knows.... id like to have a car to putt around this cruise night season..

I will keep you all informed with the turnout, thank you to all that replied.

Matt

Last edited by Matts30coupe; 01-26-2020 at 12:58 PM.
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Old 01-26-2020, 01:02 PM   #23
Matts30coupe
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Default Re: Exhaust port crack.... need help!

Here are some pictures
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Old 01-26-2020, 01:43 PM   #24
Flathead
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Default Re: Exhaust port crack.... need help!

Wow, that's an interesting product. I need to get out more. :-)
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Old 01-26-2020, 03:16 PM   #25
Matts30coupe
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Wow, that's an interesting product. I need to get out more. :-)
We will see what happens!Fingers crossed
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Old 01-26-2020, 06:45 PM   #26
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Default Re: Exhaust port crack.... need help!

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I'd be skeptical about the durability of any form of epoxy in an exhaust port. I've seen epoxy take a lot of heat before but the gas flow in an exhaust port is almost as bad as a sand blaster flow over time. It would have to be prepped just right for it to last very long. Having hot liquid anywhere near the faying surface is also going to play hell with the bond. It might work for a while but how long is anyone's guess. It might be better to braze it with silver or brass rod.
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Old 01-27-2020, 11:01 AM   #27
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Default Re: Exhaust port crack.... need help!

No one seems to mention brazing anymore, it is a great way to repair cast iron and used to be common practice. I've had good luck with it in the past.
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Old 01-27-2020, 12:50 PM   #28
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Default Re: Exhaust port crack.... need help!

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No one seems to mention brazing anymore, it is a great way to repair cast iron and used to be common practice. I've had good luck with it in the past.
I'm a big fan of brazing, and have a particular love for silver soldering. The material flows better than brass. I find it a simple and effective solution for many repair situations. One thing I've learned recently is to pay attention to the thickness of the material. Thinner areas of cast iron cool at a much faster rate than thicker areas, and will crack when cooling. Particularly in engine blocks where there is a huge heat sync, the repair will crack if thin.
After applying the solder, immediately peen it, then with a low flame control the cooling down rate, and you will greatly reduce the chance of a cooling crack. You just have to get the feel for the temperature control.
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Old 01-27-2020, 02:18 PM   #29
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Default Re: Exhaust port crack.... need help!

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Matt,
this is a good candidate for the block sealers available in a bottle.
the active ingredient is sodium silicate, or also known as liquid glass.
being this is a low pressure area and in the hot exhaust it will seal quite well.

depending on the water pump you have, you may need to reseal it if it starts to leak.

John

I have a B engine with the same problem, gave it about 3 doses of "Stop Leak" from NAPA, don't remember the brand. Stopped it completely, no leakage in almost 5 years. Worth a try and easy.
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Old 01-27-2020, 06:10 PM   #30
J and M Machine
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Default Re: Exhaust port crack.... need help!

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Originally Posted by Russ/40 View Post
I'm a big fan of brazing, and have a particular love for silver soldering. The material flows better than brass. I find it a simple and effective solution for many repair situations. One thing I've learned recently is to pay attention to the thickness of the material. Thinner areas of cast iron cool at a much faster rate than thicker areas, and will crack when cooling. Particularly in engine blocks where there is a huge heat sync, the repair will crack if thin.
After applying the solder, immediately peen it, then with a low flame control the cooling down rate, and you will greatly reduce the chance of a cooling crack. You just have to get the feel for the temperature control.

I would be weary of brazing a Model A as the iron is an uneven thickness and you will end up doing more damage than the initial crack you're trying to repair. The pictures I have posted represent a brazing job on cylinder head from the Navy base in Richmond, a submarine welder I was told. i peeled it off like old gum.
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Old 01-28-2020, 10:02 AM   #31
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Default Re: Exhaust port crack.... need help!

Welding and soldering are two different procedures. If a part is cleaned properly and a good flux is used, silver or brass will stick but old engine parts made of cast iron are very porous and hard to clean. The water jacket spaces around the exhaust pockets were one of the things that Ford engineers (Harold Hicks) and pattern makers had to improve upon in the initial development of the model A engine. The model B engine castings may have been even more thin in this area.

I've brazed up cast iron cylinders and heads for the early Harley Davidson motorcycle engines and never had problems but they are air cooled. When coolant or ethylene glycol has saturated the iron castings, it's almost as bad as oil to get it clean. An engine block would have to be cleaned very well inside and out to get a solder to fill into the porous substrate properly.

The ideal way to repair it would be fusion welding with cast iron but it wouldn't be cheap. Inside the exhaust pocket, it wouldn't be easy either.
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