compression tester

[TVZ]

Recently it was described here how you could buy an elbow from plumbing place; screw that into the spark plug hole; then insert your compression tester into that.

What if it doesn't get tight until it's still at an impossible angle (like facing forward or backward)? Is it ok to back off a quarter turn and still get valid results?

Also, does anyone know the technical description of the threads that are needed on the elbow, to fit the spark plug hole?

Thanks.

 

[Bruce (VA)]

You will have a hard time getting an elbow to fit the plug hole because they are 14mm straight thread. What I did was get a compression tester w/ two adapters. One is 14mm straight thread, just like the N & the other is, I think, 18mm. You screw the correct adapter in the head & the hose goes into the adapter. But, to make it easier, I took the 14mm adapter to the plumbing counter in the hardware store & found a brass T that fit the adapter on one side & the hose on the other. Now, I just screw the 14mm adapter into the head w/ the T already on it then screw the hose into the T. But, if you can find a T w/ 14mm straight threads on one side, you save a step.
50 Tips

 

[TheOldHokie]

(quoted from post at 20:32:28 01/23/09) Recently it was described here how you could buy an elbow from plumbing place; screw that into the spark plug hole; then insert your compression tester into that.

What if it doesn't get tight until it's still at an impossible angle (like facing forward or backward)? Is it ok to back off a quarter turn and still get valid results?

Also, does anyone know the technical description of the threads that are needed on the elbow, to fit the spark plug hole?

Thanks.

Anybody who offered that advice is dangerously misinformed. You will not find an elbow at any plumbing store that will fit the spark plug hole. The spark plug thread is METRIC 14 x 1.25 mm - so not only is it metric it is a "non-standard" dia/pitch combination that is pretty much only used on spark plugs. Attempting to use regular plumbing or even metric hydraulic fittings in the spark plug hole will almost surely result in damage to the threads and a lot of work and $$$ to fix the damage.

TOH

 

[Tom N MS]

Here is what he was told......I think I used a spark plug anti-foul adapter..screws in in place of the spark plug then I found an elbow at the hardware store that would screw into the adapter..I know it was something I rigged up but you are probably right about being able to find one somewhere made for that purpose...

 

[TheOldHokie]

(quoted from post at 22:05:54 01/23/09) Here is what he was told......I think I used a spark plug anti-foul adapter..screws in in place of the spark plug then I found an elbow at the hardware store that would screw into the adapter..I know it was something I rigged up but you are probably right about being able to find one somewhere made for that purpose...

Well I suspected he had misunderstood the advice given. I was simply trying to discourage him from cranking a standard pipe thread fitting into the spark plug hole and roaching the threads.

TOH

 

[RogerN]

In tvz's post about running out of idea's, Bruce suggested he check the compression and to read #46 of the 50 tips. That is where it says to go to a plumbing place to buy an elbow.

 

[Hobo,NC]

I don't nor never understood what the issue is,,, I have a few tester 35 years old and they all fit no problem,,, like the ones I see made today they come with different adapters ,,, theirs nuttin exotic about a N,,, I have had to replace the adapts cuzz the hose started to deterate and mite b some what hard to bend in a tight place thats it,,, must b a cheap tool thang

 

[duey]

You can remove the hood & tank... not fun... or you could add a GASKET and see what that does for the angle of the fitting... this ain't rocket science...

 

[Anonymous-0]

My gauge has angle adapters. 2 anti fowlers with a steel elbow brazed in would work.I have 4 compression gauges at last count.

 

[gahorN]

Not MY tool...but a buddy took an old spark plug, knocked the tower and all the guts out, brazed a 90-degree fitting on it, and screwed a Milton connector (air-hose connector) into the fitting. Works great.

A rubber O-ring on the base of the spark plug adaptor (instead of the usual crush-washer) allows the tool to be screwed into the head as tight or as loose as necessary to accomodate any angle of departure (fore/aft/etc) to allow use of the gauge.

 

[TVZ]

OK, thanks all for the clarifications. Sorry for the misunderstanding.