Compression tester 10 mm screw on adapter question

[272super]

When using a 10 mm compression tester adapter( the type that threads onto an existing standard tester end) you have the issue of the adapter volume extending the combustion chamber,so to speak. How much of a difference are we talking about? Will it read 30-40 psi low or not much at all? I'm not sure if I should just get a new kit with the complete 10mm fitting and hose or just get the screw on adapter and use my existing tester? Thanks

 

[272super]

Well after some trial and error I found that if using a screw on adapter the compression drops about 40-50 psi depending on which adapter was used. I tried a 10mm and 14mm adapter for comparison. Since the adapter acts as an extended combustion chamber the reading are going to be much lower. My tester has the shrader valve on the tip of the hose,so that is not an issue with the low readings. If the adapter had a shrader valve in it, then the problem is solved,but none do that I know of.

To really get an accurate reading, I guess the answer is get a kit with a complete 10mm fitting and hose assembly. A lot of the kits do not have them-they use a 14mm and require you use the screw on adapter if you want to check a 10mm hole. Motion Pro has a nice kit and the OTC 5604 is nice as well. I'm sure there are others.

 

[Termite]

Thanks for the info. I have been wondering where to get one.

 

[stihlbro]

I was able to add a Schrader valve to the 10mm adapter. It did not cut threads in real good but it will hold. I was able to go from 90psi to alittle over 120 psi.

 

[stihlbro]