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07-01-2020, 01:28 PM | #1 |
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Location: Green Bay
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Compression tester
Does anyone have a recommendation for a compression tester that comes with
an adapter for a Flathead. Everything I see comes with mm adapters. Thanks Dave/Green Bay |
07-01-2020, 01:42 PM | #2 |
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Re: Compression tester
Aren't all spark plugs metric thread? According to Machinery's Handbook (24th ed pg 1650), there are four standard SAE spark plug threads, all metric: M18 x 1.5; M14 x 1.25; M12 x 1.25; and M10 x 1.0
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07-01-2020, 01:43 PM | #3 |
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Re: Compression tester
All ford v8 heads,flatheads from 39 aand up have 14mm spark plugs. some in the early 30s had 18 mm plugs if I remember right.
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07-01-2020, 01:47 PM | #4 | |
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Re: Compression tester
Quote:
Yup! My '34 has 18mm plugs....
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The only thing nice about being imperfect is the joy it brings to others.... "Silver rings, your butt! Them's washers!" "We shot our way out of that town for a dollar's worth of steel holes!" - from 'The Wild Bunch' - 1969 https://www.youtube.com/watch?v=7NReUd2_0u0 |
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07-01-2020, 01:56 PM | #5 |
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Re: Compression tester
Thanks. Just what I needed. That makes the search much easier.
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07-01-2020, 02:40 PM | #6 |
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Re: Compression tester
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John |
07-01-2020, 03:44 PM | #7 |
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Re: Compression tester
Model B and real early V8 had 7/8 plugs didnīt they ?
But after that metric. |
07-01-2020, 03:51 PM | #8 |
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Re: Compression tester
O'Reilly Auto Parts is where I bought mine.
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07-01-2020, 04:31 PM | #9 |
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Re: Compression tester
Ones with long rubber hoses tend to give lower readings due to hose expansion, I look for Steel cord in the hoses
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07-03-2020, 05:49 AM | #10 |
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Re: Compression tester
Don’t forget to check that the adapter for the plug hole doesn’t thread too far down into the opening.....it could hit moving valves. A guy I know used one with a long adapter plug on a fresh built engine and ended up having to replace a valve if I remember correctly.
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07-03-2020, 07:07 AM | #11 |
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Re: Compression tester
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07-03-2020, 07:54 AM | #12 |
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Re: Compression tester
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07-03-2020, 08:57 AM | #13 |
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Re: Compression tester
I've been told we ended up with mm spark plug sizes due to the influence of Robert Bosch' an early day electrical engineer and manufacturer, who was of German descent.
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07-03-2020, 08:36 PM | #14 |
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Re: Compression tester
Dave when doing the test, have all plugs removed and the throttle wide open for best results. You can test it dry then add a little oil to see if it changes the readings, do one cyl. at a time or the oil can drain by rings and give different results. I bought a Bosch tester from O'Rileys. Al
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07-04-2020, 10:23 AM | #15 | |
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Re: Compression tester
Quote:
When testing compression it's not as much about how high the gauge eventually gets, it's more about what happens on the first few compression strokes, and testing all the cylinders the same ---you have to remember that to fire there is only one compression stroke |
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07-05-2020, 12:52 AM | #16 |
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Re: Compression tester
If you have a 37 21 stud or earlier 18mm plugs. just get one of these for compression checks.
https://www.snydersantiqueauto.com/P...earchByKeyword If using 18mm I like autolite as they still have screw tops and you can run raja ends. Last edited by Tinker; 07-05-2020 at 01:03 AM. |
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