Compression tester?

Discuss all things Model T related.
Forum rules
If you need help logging in, or have question about how something works, use the Support forum located here Support Forum
Complete set of Forum Rules Forum Rules

Topic author
Modeltmike
Posts: 179
Joined: Sat Mar 09, 2019 5:12 am
First Name: Mike
Last Name: Sleep
* REQUIRED* Type and Year of Model Ts owned: I have 22, 24, 26 coupe, 25 pickup, 23 roadster, 27 touring and 26 Fordson.
Location: Kansas

Compression tester?

Post by Modeltmike » Thu Dec 16, 2021 8:26 pm

I have a “Sun” 300 psi compression tester. I use it to check my T’s and at 50 psi it barley moves the gauge. I have looked and had no luck finding a 100 psi gauge. I’ve tried putting a 100 psi gauge on my tester, but it doesn’t hold the reading. Does anyone know if there is a 100 psi compression gauge made, or any ideas so I don’t have to use a 300 psi gauge. Thanks


Scott_Conger
Posts: 6523
Joined: Sun Jan 06, 2019 11:18 am
First Name: Scott
Last Name: Conger
* REQUIRED* Type and Year of Model Ts owned: 1919
Location: not near anywhere, WY
Board Member Since: 2005

Re: Compression tester?

Post by Scott_Conger » Thu Dec 16, 2021 8:52 pm

You're looking for a pressure gauge to replace the "300" one

my internet search for "100 lb pressure gauge" brings up hundreds of gauges of every npt, dial diameter and brand imaginable
Last edited by Scott_Conger on Thu Dec 16, 2021 9:32 pm, edited 1 time in total.
Scott Conger

Tyranny under the guise of law is still Tyranny

NH Full Flow Float Valves™
Obsolete carburetor parts manufactured

User avatar

Craig Leach
Posts: 1906
Joined: Tue Jan 08, 2019 12:22 am
First Name: craig
Last Name: leach
* REQUIRED* Type and Year of Model Ts owned: 1919 Firetruck/1922 Speedster
Location: Laveen Az

Re: Compression tester?

Post by Craig Leach » Thu Dec 16, 2021 9:04 pm

Hi Mike there are almost no compression gauges with a gauge lower than 300 psi. to take a compression test you need a good check valve to hold the pressure and a way to release the pressure. Most gauges use a shraider valve type set up to do both. not sure what you tried? from what I can figure out the sraider valve is not the same as a tire valve. and do not last very long. ( may be the heat ) Most screw in compression gauges will accept the 100 psi gauge in place of the 300 psi one. If the have a sepporate valve. ( you will need to adapt the 14mm to 1/2" pipe )
Carig.

User avatar

Steve Jelf
Posts: 7238
Joined: Fri Jan 04, 2019 9:37 pm
First Name: Steve
Last Name: Jelf
* REQUIRED* Type and Year of Model Ts owned: 1923 touring and a few projects
Location: Parkerfield, Kansas
Board Member Since: 2007
Contact:

Re: Compression tester?

Post by Steve Jelf » Thu Dec 16, 2021 9:35 pm

What Scott said. Google 100 psi pressure gauge and take your pick. Take the 300 psi gauge off your tester and replace it with the 100 psi. You will probably need to make an adapter with 1/2" npt thread.

IMG_0388 copy.JPG
My tester had a tire fitting, so I soldered the business end of a Schrader valve into a 1/2" pipe plug.
The inevitable often happens.
1915 Runabout
1923 Touring


Scott_Conger
Posts: 6523
Joined: Sun Jan 06, 2019 11:18 am
First Name: Scott
Last Name: Conger
* REQUIRED* Type and Year of Model Ts owned: 1919
Location: not near anywhere, WY
Board Member Since: 2005

Re: Compression tester?

Post by Scott_Conger » Thu Dec 16, 2021 9:39 pm

Craig

as an aside, I put together a dandy compression tester just as you described. I love it...and at the time I made it, I loved it so much, I made 6 more and tried to hawk them. The whole project was entirely unsuccessfully. No one else shared my enthusiasm, even at cost. I eventually gave them all away, and at $0 there was great enthusiasm among each of the 6 new owners. No entrepreneur wants to be known for just making door-prizes, so the entire venture was those 7 original units and that was it.
Scott Conger

Tyranny under the guise of law is still Tyranny

NH Full Flow Float Valves™
Obsolete carburetor parts manufactured


Norman Kling
Posts: 4634
Joined: Tue Jan 08, 2019 1:39 pm
First Name: Norman
Last Name: Kling
Location: Alpine California

Re: Compression tester?

Post by Norman Kling » Thu Dec 16, 2021 9:51 pm

Scott,
That looks like a very good idea. Most gauges don't have a pipe connection. The one I use has the valve and as you say doesn't hold for long. And since it just has a tapered rubber fitting to jamb into the holes I just hold it in my hand while someone else pushes the starter button and I look at the gauge while it is in.
Norm


Scott_Conger
Posts: 6523
Joined: Sun Jan 06, 2019 11:18 am
First Name: Scott
Last Name: Conger
* REQUIRED* Type and Year of Model Ts owned: 1919
Location: not near anywhere, WY
Board Member Since: 2005

Re: Compression tester?

Post by Scott_Conger » Thu Dec 16, 2021 9:57 pm

this compression tester: https://www.amazon.com/Engine-Compressi ... 6651&psc=1

with a 100lb gauge swapped out, and a 1/2 npt end grafted on is a terrific tool.

After 3-4 compressions, all of the tubing volume is accounted for, and ultimate compression is reached and measured. Lots more cranks will not increase the compression. After the ultimate pressure is attained, it is held for review until released with the button and is an ideal one-man-band tool, and especially handy on a stem-winder.
Scott Conger

Tyranny under the guise of law is still Tyranny

NH Full Flow Float Valves™
Obsolete carburetor parts manufactured


Topic author
Modeltmike
Posts: 179
Joined: Sat Mar 09, 2019 5:12 am
First Name: Mike
Last Name: Sleep
* REQUIRED* Type and Year of Model Ts owned: I have 22, 24, 26 coupe, 25 pickup, 23 roadster, 27 touring and 26 Fordson.
Location: Kansas

Re: Compression tester?

Post by Modeltmike » Fri Dec 17, 2021 6:33 am

Thanks for the info. I removed the 300 psi gauge from my tester which is above the valve. I replaced it with a handful of different 100 psi gauges and the gauge itself leaks down by the time I want to read it. Any suggestions on where I should find a 100 psi gauge? I see the gauge for fuel injection is 100 psi. Not sure if a gauge used for liquid can be used for air. Thanks


Dave Young
Posts: 235
Joined: Sun Feb 24, 2019 9:37 pm
First Name: David
Last Name: Young
* REQUIRED* Type and Year of Model Ts owned: 26 Touring, 26 RPU, 24 Coupe, 26 Speedster, 28 Chandler, 29 Chandler, 29 A
Location: Mays Landing, Nj

Re: Compression tester?

Post by Dave Young » Fri Dec 17, 2021 6:40 am

Just go to any hardware store and go into the plumbing section. Get a 60 or a 100 psi gauge. Water or air doesn’t matter.


J1MGOLDEN
Posts: 1230
Joined: Sun Jan 06, 2019 5:39 pm
First Name: James
Last Name: Golden
* REQUIRED* Type and Year of Model Ts owned: 1926 Model T Roadster
Location: Bowie, MD

Re: Compression tester?

Post by J1MGOLDEN » Fri Dec 17, 2021 8:01 pm

Compression Gauges.jpg
Compression Gauges.jpg (31.03 KiB) Viewed 3026 times
The best choice is to buy a cheap one from Harbor Freight, remove the 300 psi gauge, and buy a 100 psi tree sprayer compression gauge from Tractor Supply.

The most accurate area of those gauges is the center third dial area and 50 psi is the most likely reading.

The device also has a valve to hold the pressure and a button to release it.

You will also need a 14 mm to 3/4th inch pipe thread adapter, like is used for modern spark plugs in the Model T engine.


Art M
Posts: 964
Joined: Wed Jun 19, 2019 12:57 pm
First Name: Art
Last Name: Mirtes
* REQUIRED* Type and Year of Model Ts owned: 1923 Touring
Location: Huron, Ohio
Board Member Since: 2016

Re: Compression tester?

Post by Art M » Sat Dec 18, 2021 2:31 pm

The adapter is available from many of the model t suppliers.
The size I've 1/2 pipe thread.

Art Mirtes


Art M
Posts: 964
Joined: Wed Jun 19, 2019 12:57 pm
First Name: Art
Last Name: Mirtes
* REQUIRED* Type and Year of Model Ts owned: 1923 Touring
Location: Huron, Ohio
Board Member Since: 2016

Re: Compression tester?

Post by Art M » Sat Dec 18, 2021 2:32 pm

The adapter is available from many of the model t suppliers.
The size I've 1/2 pipe thread.

Art Mirtes


Art M
Posts: 964
Joined: Wed Jun 19, 2019 12:57 pm
First Name: Art
Last Name: Mirtes
* REQUIRED* Type and Year of Model Ts owned: 1923 Touring
Location: Huron, Ohio
Board Member Since: 2016

Re: Compression tester?

Post by Art M » Sat Dec 18, 2021 2:32 pm

The adapter is available from many of the model t suppliers.
The size I've 1/2 pipe thread.

Art Mirtes

User avatar

Steve Jelf
Posts: 7238
Joined: Fri Jan 04, 2019 9:37 pm
First Name: Steve
Last Name: Jelf
* REQUIRED* Type and Year of Model Ts owned: 1923 touring and a few projects
Location: Parkerfield, Kansas
Board Member Since: 2007
Contact:

Re: Compression tester?

Post by Steve Jelf » Sat Dec 18, 2021 3:04 pm

You will also need a 14 mm to 3/4th inch pipe thread adapter...

14mm to ½" NPT
The inevitable often happens.
1915 Runabout
1923 Touring

User avatar

walber
Posts: 239
Joined: Sun Jan 06, 2019 12:55 pm
First Name: Walt
Last Name: Berdan
* REQUIRED* Type and Year of Model Ts owned: '18 Speedster had 25 touring and 26 coupe
Location: Bellevue, WA

Re: Compression tester?

Post by walber » Sat Dec 18, 2021 3:50 pm

My 60's vintage gauge has the rubber nipple to fit that era plugs. I took an old Champion spark plug apart, scrapped the porcelain and put the collar back in it. Screw the plug in the head and then use my original gauge and it works just fine.


J1MGOLDEN
Posts: 1230
Joined: Sun Jan 06, 2019 5:39 pm
First Name: James
Last Name: Golden
* REQUIRED* Type and Year of Model Ts owned: 1926 Model T Roadster
Location: Bowie, MD

Re: Compression tester?

Post by J1MGOLDEN » Sat Dec 18, 2021 6:28 pm

Art, you are right, the size is measured on the inside of a pipe and outside of tubing.

I get mixed up, it is called dyslexia and old age.

I had the dyslexia first.

I did get have an adapter that was welded in to an old two piece spark plug that worked good for a long time.

User avatar

TFan
Posts: 386
Joined: Sun Jan 06, 2019 2:24 pm
First Name: Jim
Last Name: Riedy
* REQUIRED* Type and Year of Model Ts owned: 26 Roadster
Location: Sandusky,Ohio
Board Member Since: 2005

Re: Compression tester?

Post by TFan » Sat Dec 18, 2021 10:58 pm

This would probably be the period correct one to use, it's a K R Wilson and the tip fits into the plug hole and expands when the lever is brought down against the stem it most likely had different rubber tips for other applications. Jim
DSCN0953.JPG
DSCN0954.JPG
DSCN0955.JPG
Back road kinda guy stuck on the freeway of life.

Post Reply Previous topicNext topic