Compression gauge question.

[pgmrdan]

I want a compression gauge that has the assorted attachments for threading into multiple sized spark plug holes.

What sizes are there?

I've seen metric sizes. Are there fractional inch sizes also?

Do most compression gauges come with the rubber tipped adapter for when you run into a spark plug size for which you don't have an adapter?

And if you can recommend a good brand and source I would appreciate it. (The Lisle is about the only compression gauge I've seen in a long time and it only had 2 sizes of fittings. I would think there would be more than that but I'm not sure.)

Thanks.

[projectnut]

The most popular sizes are 14MM, 16MM and 18MM. There are other sizes like 10MM and 12MM primarily used on motorcycles. Snap On makes 2 sets one for cycles and another for cars and trucks but they aren't cheap @ $257.00 and $216.00.

http://buy1.snapon.com/catalog/tools...e=snapon-store

There are also other fractional sizes used on older antique gas engines, but I doubt you'll ever use them.

[pgmrdan]

There are also other fractional sizes used on older antique gas engines, but I doubt you'll ever use them.

Oh, good! I was afraid my 1949 MH Pony and 1969 Ford 3000 tractors might need something special. Whew!

Just kidding, of course.

Thanks for the information.

Does anyone recommend anything less pricey than Snap-On but not as cheap as Harbor Freight?

[saltmine]

I've worked on a few antique engines that used 1" pipe thread for their sparkplugs. Boy were they a bear to get out.

Usually, on old engines, you can stick your thumb over the plug hole, if you feel anything that resembles compression, it'll run.

I've got three compression gauges, and two of them are Strap-on. One thing nice about them....if you need an adapter, they'll sell you one without having to buy another gauge.

[Ken_Shea]

OTC makes pretty good stuff, this unit seems pretty complete as well.
Spark Plug Adapter Thread Size
10mm, 12mm, 14mm, 14mm long reach, 14mm deep well, 16mm, 18mm

http://www.summitracing.com/parts/OTC-5605/

[EddyCurr]

Have you considered getting a Leak-down tester in lieu of a compression
tester?

While a leak-down test is more complex to administer and requires a source
of compressed air, along with a means of holding the crankshaft from turning,
the results are more meaningful.

A few brands and sources to consider

Star CLT2PB - Cylinder Leak-Down Tester

Engine Leak Down Tester — 73010

One description of how to perform a leak-down.

Cylinder Leak Down Testing

.

[Video Man]

Here's an idea: http://www.sears.com/shc/s/p_10153_1...u=00947089000P

At the risk of being charged with heresey, a compression tester ain't rocket science, the Horrible Freight one would probably work just fine...I bought a cheap Sears one about 30 years ago and it's worked perfectly well all that time....and probably no better than the HF one...my 2 centavos....

[Carld]

I have an old Snap-On set and I think there are four adapters in the kit and I made a couple more. There are a lot of spark plug sizes if you go all the way back to the beginning of the gas engines. The good thing is if you have a spark plug that fits your engine you can make it into an adapter.

[projectnut]

Matco and Mac also make compression gauges. They're a bit cheaper than Snap On but still as not cheap as HF.

Matco:
http://www.matcotools.com/Catalog/to...&page=2&#52393

Mac:
http://www.mactools.com/SearchResult...pression+gauge

[garagemark]

Unless you are going to make your living with it, the Sears unit will do you well. I have had one for umpteen years and have used it maybe four times. It just ain't worth Snap-on quality