I bought a complete 1981 280ZX for the whole drive train. The engine is not running and supposedly it's just a fuel issue. I pulled the spark plugs and it seemed each cylender was dry after trying to start it.

Well I did a compression check, I need some advice. First off this motor has been sitting awhile and the head was rebuilt not to long ago, but I don't know how many miles have been put on since it was rebuilt.

I did a compression check on each cylinder three times. Pulled all the plugs first. Then started on number one cylinder.

1. 139, 170, 170

2. 130, 138, 170

3. 180, 180, 180

4. 183, 182, 183

5. 180, 149, 100, 115 then added Marvel Mystery oil in cylinder 140, then added more oil 150, then tested it again with out adding oil. 140, 150, 150

6. 183, 183, 183

So what do you all think? I wanted to drop this whole motor and tranny minus the fuel injection stuff in my 240z.. Is this bad rings in this cylinder or does this mean a valve is not seating??

Any help would be greatly appreciated. I don't have a lot of money right now and don't know if I should just do the swap and see if it will run?

Thanks..

Waylon

Could be a bad valve . However since the engine hasn't run in some time It could be a chunk of crud on a valve seat that is keeping the valve from seating . Whish I could be of more help. Gary

Those numbers aren't that bad. Really bad rings or a stuck valve will net you much less pressure. I'd use the motor as is.

Here's something I have done in years gone by that has definitely worked on motors with erratic/low compression.

NOTE!!

This technique WILL create more smoke than the '94 bushfires, so keep this in mind when you choose a site to start work!

Remove all sparkplugs. Remove airfilter box from carby.

Add 20 ml of your choice of upper cylinder lubricant/ cleaner to each cylinder through the plug hole (I used on old plastic syringe with the prescribed amount of "REDEX" but I'm not sure if it's available in your neighbourhood!)

Let this sit overnight if possible, but at least a coupla hours.

This is where it gets a bit messy. Cover the open plug holes with a rag or other absorbent material to prevent the expelled leftover lubricant/cleaner spraying your engine bay ...and you!

Spin your motor on the starter for a count of five.

Remove rag/material from engine bay.Replace sparkplugs.Clean up.

Start engine and raise idle to around 1500-2000rpm.

For a downdraught carbied motor, slowly dribble about 100ml down the intake.

For twin sidedraughts, perhaps a syringe with a bit of flexible tubing?

Apart from replacing your airbox and going for a bit of a drive to blast the remnants out of the cylinders...that's about it!

The idea is the lubricant/cleaner soaks into any carbon and varnish around the rings and the ringland areas of the pistons, softening the rubbish and breaking it's "grip" removing any restriction to the ring sealing action. The shot through the carby is aimed at the valve seat and immediate area, usually better served by cleaner fuel and additive/cleaning agent added to tank fill ups over a longer period of time.

This is a basic cleaning process, if the gunk isn't there to begin with, it's not going to have much of an effect. Oh, and for the comments you'll no doubt get during the first 5-10 mins of driving after trying this....tell 'em it's a limited edition 2 stoke version of the Datsun Z. :laugh:

In my experience, the motors that showed improvement after this treatment were much easier to tune afterwards.

Good luck with it,

Jim.

Thanks for your help guys. I got her running, the main thing was the injectors where stuck. I had two spare that came with the car and switch two out ended up working out. It doesn't run all that great but it has been sitting for a while. I am going to get the 280zx drive able and take a for a drive and make sure the tranny is good also. I know the throw out bearing is bad but I plan on replaceing all that.

With some luck it might just turn out to be a good motor. Thanks ...

run some injector cleaner in the gas for a tank or two. This may help a lot if they are slightly blocked and like the privious suggestion it wont heart any thing in any event. My truck and family car are injected and I do this about every 6 months . Marviel Mystery oil will suffice in the oil treatment mentioned to loosen the rings . I don't recommend oil additives in the crank case as it tends to dilute the good oil that you should be using. I use about a teaspoon full of Mystery oil in each cylinder . More than that just makes a mess and is blown out the plug hole when you spin the engine.

Nice information, im going to do that when I get my car. ;o