Compression Test

[bloxman]

Morning

So the results are in

from the back (firewall) to the front(radiater)?sp

150, 152, 170, 160, 155, 160

The plugs were black powdrery so too rich right across the board the fourth plug(160) was a trifle black and damp looking

(just a little richer again ?) didn't look like oil (not that wet looking)

So whats the general consensus on the compression

Good

Bad

Indifferent

In general I find the car to be a lot less powerful than I would expect.

Anyhow , thats another matter we can sort out It may have to do with the gearbox /diff combination, and tire size.

Regards

Bloxman

[nwcubsman]

Not enough difference for a rebuild, IMHO. I'd wait till I was going in there for another reason. Adjust the valves, tune the carbs, enjoy the car.

[MikeW]

According to the factory service manual: "No cylinder should be less than 80% of the highest cylinder"

150/170 = 88%

You can always add some oil to each cylinder and run the compression test again. This will help determine if it is rings or valves that is causing the difference.

[bloxman]

nwcubsman, and MikeW

Thanks for your thoughts guys!

any particular oil I should be using for this test;?

or should it be same rating as in the engine at the present.

and while we're talking about oil;

I currently have 10w30 but put this in only for initial start-up and fiddling in the garage.

It would normally use 20w50 in a gasoline engine in the Grenada. Temperature is typically 84' all day every day. Average speed probably hovering around 40-50 mph to and from work (around elen minutes each way) ,with some stop and go during the day (coffee, errands and lunch).

any reason why I shouldn't use 20w/50?

Have a good dayeveryone

Bloxman

[nwcubsman]

Blox,

It is my belief that a factory engine has relatively loose tolerances by todays engine standards. I would run 20w/50 as a general rule, and I don't live in the temperate climate that you do. I don't live in a snow zone either, but today is supposed to be 52 degrees, for example

[Nissanman]

Adding a squirt of engine oil to the cylinders will improve the reading normally, but, the test should be done on an engine which is at operating temperature.

I know that makes things a bit hot to remove the sparkplugs, but it will give a better indication of the operating compression values.

Then you can compare those you took on a cold engine to hopefully see a marked improvement:nervous: