Modifying cheap compression tester adapters for more accurate readings.

The affordable compression tester kits come with adapters that don't have their own check valves (Schrader) in the adapters and rely on the one in the hose. This adds the adapters volume to the chamber yielding an inaccurate compression reading, especially on small engines. This is how I remedied that.
Replacement valve cores for gasoline compression testers with low pop off pressure are easy to find.

[@Srdieselshawn]

Very neat

[@Shamap37]

Do you have a link to order those valvs? I find only the one with stiffer spring

[@srcarr52]

www.ebay.com/itm/256348796802?hash=item3baf943782:g:hbwAAOSwZpRaupCV&amdata=enc%3AAQAIAAAA0FALyRCns45iHsKWV7nMt%2FuUv0HGwEVIaNl%2BHH%2BmNetyEZYbMxi%2FJmEFyGMfv4ESU5fHlkgFzsfTaCLF1eeMAyHVHQNN88i0wpYfBSzChcPisYTNFnCaeREVswFLE3xJANJObfYjj5vXJq5r2f0%2FP%2FCZ38ffXROyiyljOF2JF1W2OktrHHdv7LjDxqK4oPK7w%2FQ8w5w4Nr60mPR8OMYltL8dtGCG0wbJQG9BOLge6%2Biagdv4XDNEkNYAHLsFRwdToNRDk5kyk2VEGXt4pY42Rs4%3D%7Ctkp%3ABk9SR_iI-d6xYw

[@wcjcnc]

I tested compression on a Stihl blower that has 10mm spark plug threads. With a thread adapter on my compression tester I got 100 PSI. With a hose that has the schrader valve right there in the tip of the threads I got 160 PSI. So I had a 60 PSI difference between tests. Does that sound right?

[@srcarr52]

That sounds pretty typical.

[@Oli4vn]

Is this just a standard Schrader core being used?

[@srcarr52]

I was using a standard core for a test fit, you need special low opening pressure Schrader cores to get accurate compression measurements.

[@Oli4vn]

@@srcarr52 thanks! I'll give it a try with those, now I just hotglued in a regular valvestem but it does not give accurate readings I think

[@patrickallred850]

Are you selling them?

[@srcarr52]

No, this is why I gave all the info to make the modification.

[@patrickallred850]

@@srcarr52 Thanks Brother.. Do you have any hand pieces finished yet?

[@srcarr52]

@@patrickallred850 Sorry, not yet. I've been busy with other projects.

[@srcarr52]

@@patrickallred850 I have handpieces on my website now, luckydogmfg.com/products/angled-porting-handpiece-kit.