Compression can range from 120 - 170 but Mustang5L5 is correct consistency is key!! 10% variance between cylinders is optimal.
Get the engine warm. The difference in temp can make a difference.
Pull all spark plugs. This allows the engine to spin at a higher RPM and gets a better reading, also easier on your starter and battery. Just the proper way by the book as well.
Either disconnect the power to the fuel and spark, or better yet, turn the motor over by jumping the solonoid. Ignition systems don't like to be ungrounded, you don't want to be the ground yourself, nor do you want to start any fires, so disconnect the ignition. If the injectors are spraying fuel, it may alter the test results by the fuel buildup and/or the fuel washing down the rings. If you just jump the solonoid, neither one of these will be active and you will get the best results.
Have something hold the throttle wide open, so the air supply doesn't alter the results.
When spinning the engine over, note the time it takes to build compression. 70psi is minimum for combustion. I've noticed that engines with worn rings tend to take a while to get usable compression. If some cylinders are way down, that is a good indicator you have a problem with that cylinder.
Then there is the leakdown test. There is a tool for this, but you can also hook up a compressed air supply to the cylinder on it's compression stroke and listen to see where the air is going and how much is leaking from the cylinders.
Thank you for the advice, I should be able to get the readings tonight. I have the kit ready to go. I also am going to do the test with two other guys whom have performed the test before.
Also Iridium plugs were recommend, anyone second that statement? Maybe have another opinion?
Any advice is more than welcome. Thank you for all advice so far!
Anytime.
Copper plugs for our cars. My truck runs irridium plugs, expensive bastards that were designed for the truck, which has coil on plug, runs much more voltage, but goes 100K between tune-ups. You will probally only have poor performance and foul the iridiums on your motor.
Stock Ford motorcraft copper plugs. Cheapest plug on the market, but for some reason the 5.0's love them.
Not like doing a plug change on a 5.0 is hard. No real reason to run anything else if you are N/A.
Now if you had a power adder, then i'd go NGK iridium's
Stock Ford motorcraft copper plugs. Cheapest plug on the market, but for some reason the 5.0's love them.
Not like doing a plug change on a 5.0 is hard. No real reason to run anything else if you are N/A.
Now if you had a power adder, then i'd go NGK iridium's
I've been running Autolite iridium plugs for years. No problems here.
Also, AFR may have a "suggested" plug for their heads. You should look into that.
Yes, they're perfectly fine. Quit sweating it. Raise that gap up about .005
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