Freestyle What compression testers are acceptable?

[NVJAY775]

I have heard that Snap On is the way to go, but have also heard that there are others that read accurately? I was told from a hot rod builder that the Lisle's are very accurate and reliable, so I picked one up last season. I compared it to a Snap On and it was spot on last season. Anybody else have any experience and recommendations? Just don't want to shell out the big bucks on a tester, If I don't need to. Pretty sure my Lisle is still fine, I'm just curious what others have experienced?

Thanks fellas!
Jay

 

[kurtwolff]

Lisle is a good one. The gauge will last a good long while if you keep from blowing water and oil into it. You can replace your gauge head itself with a Matco off the tool truck for $12, that is what I did when my Craftsman started reading weird


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[NVJAY775]

That's good to know! I'll hit that up if needed.

 

[Quinc]

I tested my Harbor freight against my dads Snap on and it was the same. I will test it again in a couple months and see if it holds.

 

[yamijumpn]

i have had problems iwth the Harbor freight ones being like 20% low since the put the check valve at the gauge instead of near the spark plug location. seems as though all that extra hose volume makes for a lower compression test.

 

[OCD Solutions]

I went thru a couple of the cheap ones ($35 or so) before finally biting the bullet and committing to buying a Snap-On tester and I was shocked at how cheap they were. I actually picked up my set off ebay for around $50 plus shipping. (maybe $65 total). Made me wish I had bit the bullet and bought a good one years earlier.

 

[Balduccimoto]

I am using the auto zone compression tester, I think it's Actron or something. I've had it for years and has always been reliable. I checked a few years ago by plugging into my air compressor to see if it were spot on with my regulator and another gauge I had laying around. There's an idea for anyone who doesnt have another compression tester to check for accuracy.

 

[amitchell]

My cheap tester reads about 40psi lower than my Snap-on. Which is scary because the cheap one was reading 190 psi on my 550's .

 

[mxr181]

I feel like the snap on gauge tends to actually be on the high side. I've had it read 170psi multiple times on a couple completely stock unmolested 701s (head never even removed). From what I have seen they should be about 150

 

[Lumpy]

I bought a cheap tester from advance auto parts and it tells me im getting 225 psi on an unported 701 with ada girdled head on 33cc domes. Seems a little high to me.

 

[Henry Stephen]

that's not acceptable....

 

[Joker]

Matco for the win

 

[Harbor]

Me and amitchell tested the difference in compression readings using the wrong reach adapter hose verses the correct reach adapter hose On the Snap On gauge. Using the wrong reach adapter "short adapter in a long reach spark plugged head" lowered the compression reading on the gauge by 10 psi as compared to the correct long reach adapter.
I'd assume the a long reach adapter in a stock head would incorrectly show 10 psi higher compression assuming the piston cleared the adapter......

 

[DAG]

no 1 gauge is a good one, whatever you get have 2 of them so you can make sure they read the same.

 

[tor*p*do]

no 1 gauge is a good one, whatever you get have 2 of them so you can make sure they read the same.

and then you will be the guy with two watches who never really know what time it is!

 

[DAG]

lol, true.. but i only say this for compression gauges... They don't stay calibrated well when the piston forces premix up into them (it doesn't take much). Its about the only tool I'd rather be out the same money for 2 cheap ones than 1 nice one.

 

[tor*p*do]

my cheap HF tester has dropped about 25 psi since i bought it

 

[Harbor]

My snap on is more than 5 years old and I also do running compression tests with it without issue when compared to my co-workers gauges

 

[mxr181]

Always use short adaptor...the biggest thing I look for is that the compression is even on each cylinder and really only use the actual numbers as a reference to know I'm in the ballpark and general condition of the motor is ok. I would not trust it to know whether I am safe for pump / race gas, etc.

 

[amitchell]

Always use short adaptor...the biggest thing I look for is that the compression is even on each cylinder and really only use the actual numbers as a reference to know I'm in the ballpark and general condition of the motor is ok. I would not trust it to know whether I am safe for pump / race gas, etc.

Yes I agree on the consistency of readings to monitor health. That being said, using one gauge exclusively is as important as the quality of the gauge.

You really should use the adapter that matches the reach of your plug for best results.

I trust that my snap on is accurate to within 1-2% when well taken care of.