first compression test

[1930artdeco]

So I did my first compression check on my engine that I got for my wagon. Here are the results-I ended up using an O-Reilly gauge as that is all had at the time. Opinions please (first test/second test):


1-100/110
2-0/0
3-50/50
4-45/35
5-40/15
6-50/0
7-40/0
8-30/0


The valves were adjusted to .020 cold per the book (used Tim McMasters method) and this gauge is the screw in type. I checked #2 with my grandfathers hand held gauge and it registered 30#. #1 it blew my hand off of the head so I could not verify the reading. I suspect the valves my be the cause so I rechecked and adj. a few on the drivers bank and here are the numbers:


5-40/40
6-20/20
7-45/50
8-30/30



It is possible that the valves are good but the guides/seals are bad. Maybe the rings? But all indications are that this engine has about 47K and never opened up. Sneaky suspicion the heads are going in.



Thanks,


Mike

 

[dmsfrr]

...
It is possible that the valves are good but the guides/seals are bad. ... Sneaky suspicion the heads are going in.
...

The valve guides and seals are (obviously) above the valve sealing surfaces in the heads and shouldn't affect the compression that much unless they're falling out of the heads.

If this is the same engine that you can rotate some of the valve springs by hand, yes it's way past time for the heads to go to the machine shop.

A normal compression reading should be a minimum of 110, preferably more.
.

 

[KULTULZ]

READ THIS - https://dannysengineportal.com/compression-test-how-to-do-it-what-can-it-tell-you/

You need a screw-in tester as the hand-held version is for a lawnmower.

With the engine cold, you are only going to get a brief idea of cylinder condition. Did you spray the piston rings with any type of solvent and let sit for a few days to try and free them up before testing? A TRUE ZERO indicates a leaking valve or hole in the piston (or possible head gasket).

After the first test, you would squirt a very small amount into each cylinder to seal the rings and if the pressure goes go, it is most likely the valve(s).

 

[1930artdeco]

There is no carb on her right now as I bent one of the little brass tubes lifting it-so it took it off. The throttles are frozen anyways. But I could hear it suck air and then the sound would go away and come back.

Either way when she goes on the stand I am going to check all of the bearings, probably replace the rear main seal and have the heads redone. If she requires a rering then I would do it the as well. This all assumes the bearings are good. Thanks for the ideas and help.

K-that is what the band held one is for, always wondered. When number 1 blew handoff it covered the gauge in oil. I had previously shot oil into each cylinder to lube the walls and poured oil over the rockers and push rods. So it is possible the pump is pumping oil and the seals swelled enough to seal just s bit. Either way I think it shop time for the heads. But this is why I did the test, so i know what I have.



Mike

 

[KULTULZ]

When number 1 blew handoff it covered the gauge in oil. I had previously shot oil into each cylinder to lube the walls and poured oil over the rockers and push rods.

When you put something (oil - solvent) into a cylinder to hopefully free rings, reinstall the plugs and let it sit for a day or so. Before attempting to start or perform a compression check, remove all plugs and spin the engine to eject any fluids that may be left in the cylinders.

Fluid(s) in the cyls could induce hydro-lock and you don't want that.

The carb off is no big deal as you prop the choke open with a screwdriver anyway so it ingests air freely during the test.

TOOL SOURCE - https://www.amazon.com/Star-Product...-Universal/dp/B000FMLYLM?tag=atomicindus08-20