compression good? still no power!

[77-Z]

My son's '77 280Z is still on it's way to becoming a daily driver...long, slow process. First we tackled the fuel system (cleaned, sealed tank, new fuel pump, good pressure 40psi to rail, new injectors). Then we replaced all vacuum hoses, cleaned all electrical connections, etc. The car RUNS but there is no power. I thought maybe I had no COMPRESSION, but today I did a compression test and came out with what seems like good compression: (1=150, 2=155, 3=160, 4=150, 5=155, 6=150). The spark plugs were black with carbon and somewhat oily. When it does run it burns a bit of oil.

If you have a suggestion I am all ears. Otherwise, I wondered how to:

• set the proper AIR/FUEL mixture on idle screw and on the throttle body screw?
  
• adjust the VALVES
  

I'm attaching a pic of the sooty plugs in case that helps at all.

I appreciate any help you can give.

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[ozconnection]

Those plugs look like they're Bosch ones......nothing inherently wrong with them but many punters out there who own L series engines swear by NGK's.

I would buy a new set of plugs. Get plugs that are hotter than the ones you're using. Hotter plugs will stay alive longer in your engine if it's too rich or burning some oil. Standard NGK's are 6's so get some 5's. Check their gaps before you put them in, too.

The photos have poor resolution, so it's hard to see if they are really oil fouled or fouled from over rich mixtures.

Good luck mate, cheers

[JohnnyO]

If it runs and you have no power I would check to make sure your exhaust is not restricted by a faulty catalytic converter.

Had this happen and there was too much back pressure. Took forever to get to highway speeds and would barely go up a hill. If I remember correctly it did smoke a bit too.

[77-Z]

Thanks for the input so far...

oz: yes, they're BOSCH plugs (I'll get the NGK as you suggest). Sorry for the pic resolution, I only have my phone camera. The plugs are black/carbon build-up but also were oily upon removal.

johnnyO: I suspected "back pressure" also and cut off what I THOUGHT was a catalytic converter (ended up being a "resonator", which was not restricted.) I appreciate your input.

[IdahoKidd]

Not really related to the black plugs but definately to the power issue, check the engine timing. Check the cap and rotor and be certain of the plug wire firing order. Does it have any other runability issues? such as slow throttle response, a miss, etc. Does it bellow smoke, smell rich when running, idle okay, back fire. The more info the better.

[77-Z]

Well, I pulled the valve cover off, thinking I'd visually inspect the timing chain & valves...I found a TON of GUNK (sludge, dirt, goop, etc). I believe this car has sat for quite a while! I sprayed some PB Blaster onto the varnish and tried scraping the gunk away from the areas so I can carefully clean it up before doing further adjustment/inspection. (I'll be sure to change the oil before running the car again in case the sludge and junk drops into the oil pan).

I also went to remove the EGR valve since it had a funky gasket on it...when I did I found the base of the EGR was cracked and the hole down to the exhaust manifold was full of rusted crud. I'm thinking I'll put a "block plate" over this?

Anyhow, any other thoughts on cleaning up the area under the valve cover, adjusting valves, etc?

Also, how do I know if my valve guides are any good? Is there a test or something to tell?

Thanks again.