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01-17-2022, 12:13 AM | #1 |
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Flathead Spark plug Thread Repair
I just picked up a set of aluminum cylinder heads for my flathead. One of the spark plug holes the threads are not in the best condition and the plus has a little wiggle. What is the best process or the best kit to use to repair this head?
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01-17-2022, 01:51 AM | #2 |
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Re: Flathead Spark plug Thread Repair
Heli coil
Lawrie |
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01-17-2022, 10:01 AM | #3 |
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Re: Flathead Spark plug Thread Repair
Yes they do a good job
R |
01-17-2022, 10:28 AM | #4 |
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Re: Flathead Spark plug Thread Repair
For the repetitive use that a spark plug thread gets I like this style over the spring type inserts. I have had luck with them on chainsaws and motorcycles with alloy heads. Helicoils, although good, have historically backed out with me when I remove a plug.
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01-17-2022, 04:03 PM | #5 |
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Re: Flathead Spark plug Thread Repair
I prefer to use Time-Serts - they are a threaded sleeve and when properly installed, really do a nice job. They are available in different lengths and they supply the various tools to do the job. The "kits" are not cheap, but many automotive machine shops will have the kits and inserts.
https://time-sert.com/ |
01-17-2022, 05:20 PM | #6 |
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Re: Flathead Spark plug Thread Repair
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Timeserts have the washer seat integral with the insert so if they have to be drilled by hand as in field repair, the seat will still be square with the thread. |
01-17-2022, 06:21 PM | #7 | |
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Re: Flathead Spark plug Thread Repair
Quote:
Me? Working on an aluminum head? Well, I'd figure I have one opportunity to do this task correctly. There's no question that I'd spend the extra money and buy the time-sert.
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01-17-2022, 06:42 PM | #8 |
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Re: Flathead Spark plug Thread Repair
Time Serts for me, I have many sizes, more $ than helicoils but so much better.
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01-17-2022, 08:09 PM | #9 |
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Re: Flathead Spark plug Thread Repair
Since you've the heads off already it is a simple matter to use a time-sert, I used these for a Lawn-Boy jug with stripped plug threads and they work really slick. Aluminum accepts a tap like butter, it's so easy a cave man could do it. The result is very strong, and permanent.
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01-17-2022, 08:15 PM | #10 |
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Re: Flathead Spark plug Thread Repair
Something that is seldom noted but essential on race engines only is, a sparkplug thread insert of any kind will normally change the plug range one notch.
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01-17-2022, 10:37 PM | #11 |
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Re: Flathead Spark plug Thread Repair
Hotter?
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01-18-2022, 01:00 PM | #12 |
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Re: Flathead Spark plug Thread Repair
Are the Time Sert inserts closed at the bottom? Hard to tell from the picts.
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01-18-2022, 01:35 PM | #13 | |
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Re: Flathead Spark plug Thread Repair
Quote:
Just kidding yah - couldn't help it! LOL Not sure what you're asking, but they are a threaded sleeve with a plug gasket sealing surface at the top. Is that what you mean? |
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01-18-2022, 02:03 PM | #14 | |
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Re: Flathead Spark plug Thread Repair
Quote:
I guess going by pictures on the internet is not the best plan of attack, but they appeared to have a closed bottom which was confusing me as to their usage for the exact reasons you joked about. |
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01-18-2022, 02:43 PM | #15 |
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Re: Flathead Spark plug Thread Repair
Pete, Why would that be?
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01-18-2022, 03:14 PM | #16 |
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Re: Flathead Spark plug Thread Repair
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01-18-2022, 04:00 PM | #17 |
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Re: Flathead Spark plug Thread Repair
Thanks Pete.
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01-18-2022, 07:22 PM | #18 |
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Re: Flathead Spark plug Thread Repair
This probably is a dumb question, but I will ask it anyway, did they ever make a adapter to change the plug size on the earlier heads that used the bigger plugs that were I think 7/8 maybe to the later size commonly used in the 59AB heads? Just curious.
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01-18-2022, 07:33 PM | #19 |
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Re: Flathead Spark plug Thread Repair
I had a set in a model A engine once. They may still be available from model A parts stores.
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