Compression tester questions, adapters

[Ign]

I've got an old Proto compression tester that used to belong to my dad. It's kinda cool and I'd prefer to just find a way to keep using it rather than buying another unit.

Today's vehicles with deep plug galleys, I'd like an extender "just in case". I see at least one on Amazon but it apparently doesn't have a schraeder valve and reviewers point out that your ultimate readings will drop because you've increased the volume of the cylinder by the amount of the extender. Valid point.

https://www.amazon.com/dp/B000EVYHAO/?tag=atomicindus08-20

Thus, question 1: can anyone point me to a quality extender that will have 14mm female threads on the top so this Proto will then thread into it?

Now it appears the Snap-On extenders/hoses (ala a MT26J200) or the OTC 5603 have a check valve but they're all quick connect so my 14mm male thread won't just fit.

Thus, question 2: failing #1, can anyone point me to a way to convert my Proto to quick connect? I've been searching the web with no success.

 

[SeisMec]

The Snap-On MT26J200 and OTC 5603 adapters are using a male, compressed air, quick connect fitting. Compressed air quick connects come in a variety of styles and the styles are not interchangeable. Buy which ever adapter you prefer (flexible hose would be my preference - you just screw the adapter into the spark plug hole hand tight - the o-ring seals it at the cylinder). When you have it in your hand, visit you're favorite, local, auto parts store to buy a female quick coupler. You will need to remove the existing hose and screw it on to the brass fitting with the side release valve. You can buy a male fitting for the hose you removed.

 

[Ign]

Ok so you believe the threads directly under my gauge are NPT? They very well may be, I haven't checked

In a perfect world I was hoping to find a female coupler (I/M unless A is the standard here) already threaded M14 on the backside for my present hose. I might be able to cobble together a bushing or something on the lathe....

 

[Djosbun]

Why would you want to use a bushing? Bushings have no threads! I have never seen a compression gauge that did not have NPT threads.

All you have to do is buy a male+female quick disconnect and some extra 3/8 hose. My self-made kit has screw-in male threads for most standard spark plug sizes. Simple stuff.

-- Dave

 

[Ign]

Alright as is so often the case Leblond makes it happen.

There would be slightly more elegant ways to do this but this was what I had in my "air fittings" drawer.

I simply drilled and tapped the ID of NPT 3/8 x 1/4 reducing bushing to M14x1.25, so now it just threads on to the existing hose.

The bushing gets to be pretty thin wall so we'll see if it blows up under pressure! I figure about 25 thou w.t.

 

[Ign]

Also I recently received the OTC 5603 and it is 1/4" I/M. I was unable to find this info anywhere.

 

[jimindm]

I have one similar to this. Unless you need a dead nuts accurate reading, I would not worry much about the space of the adapter.

Most times you are looking for a difference between cylinders. If that space is the same in all of the tests, then you get what you are looking for. In most applications.

If you you need a dead nuts accurate reading at the cylinder for some reason, you would need a passage as small as can be. I would guess they make them, but likely more than any one on here would want to pay.

 

[Ign]

I have one similar to this. Unless you need a dead nuts accurate reading, I would not worry much about the space of the adapter.

Most times you are looking for a difference between cylinders. If that space is the same in all of the tests, then you get what you are looking for. In most applications.

If you you need a dead nuts accurate reading at the cylinder for some reason, you would need a passage as small as can be. I would guess they make them, but likely more than any one on here would want to pay.

I agree, relative compression is more important