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03-21-2019, 08:25 AM | #1 |
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Location: Oakland County, Michigan
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Pressure-Sealing Blocks
Does anyone know about pressure-sealing engine blocks? I ran across an article from Hot Rod magazine the other day where they interviewed Mike Herman of H&H Flatheads out in California. He says they do this to every engine they build. It sounds like pressure-sealing could be an excellent way of addressing the smaller cracks our beloved flathead blocks tend to get.
According to Herman: "We also pressure-seal every block with a cast-iron resin that we heat to 180 degrees and pump through the water jackets at 20 pounds of pressure. It will show if there are any leaks and also coat all the water jackets. This is a must; we have been doing it for over 40 years with thousands of engines." Other than this article, I've never heard of this process before. An internet search doesn't seem to reveal much about it. Here's a link to the article in question: https://www.hotrod.com/articles/1111...lathead-motor/ |
03-21-2019, 08:37 AM | #2 |
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Re: Pressure-Sealing Blocks
I'm interested as well. I've gone through 5 blocks. Latest one, I trusted the shop to magnaflux it and they did the normal spots, but never mag checked the valley. Sure as hell, this block has a 3" straight crack right behind cylinder #8.
My builder believes it's too thin to weld this spot on the block effectively. Block had been bored and ported extensively, so I would love to find a fix for this situation. It does show up at 20 lbs while pressure testing and we don't believe this part of the water jacket would get that much pressure from the water passing through. We've toyed with using hi-temp epoxy and running sodium silicate to "fix" it. I would really like to know if this process works. |
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03-21-2019, 09:06 AM | #3 |
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Re: Pressure-Sealing Blocks
When I was working at a company that used quite a few aluminum, and bronze castings which could be porous We had the castings pressure sealed with a Loctite product These castings were used to build dynamometers that were subject to high pressure when testing various engines. After they were pressure sealed we did not have any leakage due to porosity.
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03-21-2019, 09:13 AM | #4 |
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Re: Pressure-Sealing Blocks
THANK YOU Admiral for posting that info.
Seems like a great idea. Wonder what it costs? |
03-21-2019, 09:33 AM | #5 |
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Re: Pressure-Sealing Blocks
I wonder how thick this coating is and if it effects cooling like a layer of rust inside does. Sounds like it would be good to do. I have an NOS block that would be nice to know it wouldn't ever rust due to the resin keeping water away from the cast iron.
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03-21-2019, 09:43 AM | #6 | ||
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Re: Pressure-Sealing Blocks
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Quote:
Quote:
As for your NOS block, I think rust would NOT be an issue at all, assuming you use properly mixed modern-day antifreeze. |
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03-21-2019, 10:33 AM | #7 |
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Re: Pressure-Sealing Blocks
I would think that benefits would vary for individual situations. A block that would normally be marginal would still be marginal, and some of those would fail during the process that may otherwise have been built, and further, may not have failed otherwise. This is pure speculation on my part, as "doing the math" can selectively prove or disprove such theories. One benefit that is easy to understand is that a process like this is a good marketing tool for shops that advertise its use for "every block they build".
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03-21-2019, 10:35 AM | #8 |
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Re: Pressure-Sealing Blocks
You would think if it was that great a process other shops would be using it.
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03-21-2019, 11:29 AM | #9 |
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Re: Pressure-Sealing Blocks
The process is probably quite expensive and appeals to only a few that can afford to "gild the lily", so it makes sense that only the highest end shops would do it. There are a lot of things I would like to do with the engines I build (pinned heads and bronze-lined valve guides ala' "GOSFAST" and perhaps this), but they are out of my budget and too far away. I would love to have an H&H engine, but alas, it will never happen. I'll have to just get by with my old "Tub Specials", I guess.
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03-21-2019, 11:44 AM | #10 |
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Re: Pressure-Sealing Blocks
Pressure seal costs $120. Per their catalog. Don’t know what prep before sealing would cost. They do acid dip, hot tank, etc. Costs in the catalog Mike
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03-21-2019, 11:51 AM | #11 | |
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Re: Pressure-Sealing Blocks
Quote:
If $120 would help me save a block, I'd gladly pay it plus tip. Tearing down a flathead sucks. I've done four within the past two months. My garage looks like a slaughter house for old, greasy pig iron. |
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03-21-2019, 11:54 AM | #12 | |
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Re: Pressure-Sealing Blocks
Quote:
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03-21-2019, 12:07 PM | #13 | |
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Re: Pressure-Sealing Blocks
Quote:
This block hunting is getting old quick. I've gotten to the point where I can lift a bare block in and out the truck by myself; if need be. I guess it's a good work out if anything. |
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03-21-2019, 12:21 PM | #14 |
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Re: Pressure-Sealing Blocks
I have a different aproach to sealing small cracks.
After pressure testing and finding a small crack( talking hairline ) i hook the block/head up to the vacuum pump i use for testing valve sealing. Then apply fluid weld to the crack and let the vacuum draw it into the crack. Heat cure it. Pressure test again. |
03-21-2019, 12:28 PM | #15 | |
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Re: Pressure-Sealing Blocks
Quote:
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03-21-2019, 03:49 PM | #16 |
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Re: Pressure-Sealing Blocks
If epoxy is going to be used, do research to find a better product than JB. Not that JB is a bad product, but it's consumer grade. There are better, more expensive epoxies that are used in industry and not sold in the average hardware store.
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03-21-2019, 04:32 PM | #17 |
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Re: Pressure-Sealing Blocks
More expensive products are sold to Uncle Sam in which the paper trail is actually valued more than the product itself. Traceability is of paramount importance, otherwise epoxy is epoxy, and is formulated to meet multiple specifications.
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03-21-2019, 07:36 PM | #18 |
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Re: Pressure-Sealing Blocks
My son threw a rod through the block on a 5 HP Briggs racing kart in the 90's. Since we already had quite a bit of money in that engine, I epoxied the hole with clear J B Weld. That engine ran quite a few more races, winning some and losing some, but never leaked and never blew out the aluminum block. The engine still runs and the repair was over 20 years ago.
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03-21-2019, 08:26 PM | #19 |
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Re: Pressure-Sealing Blocks
I have heard that there is something called "DevCon" that is like JB weld on steroids. I have never had an occasion to use it, but I think "Ol' Ron" has. Perhaps he will chime in on this.
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03-22-2019, 07:45 AM | #20 |
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Re: Pressure-Sealing Blocks
yes, devcon is a great epoxy that hardens like steel. i used it to repair leak in the bottom of my old air compressor tank (rust) holds well even at 175 psi.
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