1977 280z EFI Nightmare

[ckurtz2]

@zclocks Mine has a very minute wobble. Just another problem to add to the mix.

 

Ok, so I took a ton of photos and a video. I think my wipe pattern is ok-ish, but I may not understand the concept completely. Enlighten me. Also, the cam has score marks on it in certain places, does this mean I am screwed and need a new cam. I think I narrowed it down that my spray bar just isn't providing enough oil, however the engine wasn't turning fast either. Some holes in the bar had virtually no oil coming out, while some had decent spray for such low rpm. In addition, sometimes the oil looked like it was just spraying straight down. 

Does anyone know how to disconnect and make no spark get to the coil. It was really annoying watching the spark arc when cranking. 

 

[Patcon]

Be careful running your starter that long! You can burn it up

[siteunseen]

If the valves were out of whack, some too tight,some too loose, you'll get some shiny (too tight) some darker (too loose) cam lobes plus the spray bar having uneven oiling.

 

 

 

[zclocks]

Good pix of the cam. Looks like you have so damage. Could be the oil galleries  in the spray bar are plugged. I would remove the spray bar and make sure they are not plugged. Also check the holes in head that attach to the spray bar to make sure they are open. Also, I think there are gaskets the the spray bar attaches. Make sure these are not leaking.

As a note: I'm not sure  that the 77 had a spray bar. My 75 cam was damaged (loud lifter noise/couldn't adjust out)  I replace the cam with a 77  or I believe it was a 77 cam. The new cam was used and had holes in the cam lobes . This eliminate the need for the spray bar. 

Maybe someone else can chime in on this.   

 

[siteunseen]

My 9/76 had an OE N47 with a spray bar and internal oiling cam.

Looks like has an N42?

Edited May 21, 2021 by siteunseen

[zclocks]

So you had a internal oil cam and spray bar? I was told by a Z mechanic if you used both you wold have very low oil pressure. 

Ron

[Zed Head]

The cam lobes that have a shiny line all the way around the lobe are probably too tight.  The portion of the lobe with no ramp should not be contacting the rocker arm pad.  That's where the lash, or gap, is measured.  I'd recheck all of the lash measurements.

Hard to tell on your spray bar.  The head bolts and various crevices are all full of oil.  Probably fine once the engine starts.  Your cam doesn't look bad considering the time that it's been running.  Once they start to grind up the lobes it happens pretty fast.

Disconnect the negative terminal of the coil and the sparking will stop.

Somebody just posted about blocking an EGR and I remembered the problems people have had with internal EGR leakage.  You might check your EGR passages to be sure that they're actually blocked off.  Might be one of the mystery sources for some of your problem.

[ckurtz2]

Wow, thanks for all the replies! Do you think it is ok to keep running that cam for now?  So I think the issue with it's oiling efficiency is that I half assed the gaskets. I used a cork type gasket instead of rubber, because it is what I had at the time. You can see the cork is sopping wet, because it is obsorbing the oil and I am sure letting some leak out. I am going to find a rubber sheet somewhere and make new ones, hopefully that will help. None of the galleries were clogged. New valve adjustment coming up as well.

The car is a 1/77 280z. So I am not sure when they switched to an internally oiled cam. This is what the car had when I got it, and it was a pretty unmolested car. Is an internally oiled cam better? 

Anyhow, decided to switch things up today and got started on the brakes and regreasing wheel bearings. Lemme tell yah, that rear nut on the rear stub axle is a real enemy. Haven't figured out how to defeat it yet. I am thinking a punch to open up those crimped edges, and then an impact at maximum uggah duggas. Oooh the fun...

I have the potentiometer coming in tomorrow. I will try the new gaskets and see if it quiets down the motor. Then I will fit in the potentiometer and see what fun it brings. The weird thing is that the spark plugs all look slightly carbon fouled. However, the car ran on crazy advance for a while so I won't be surprised if that caused that. The ground electrode was slightly white, while the center electrode was black.

[dutchzcarguy]

11 hours ago, zclocks said:

So you had a internal oil cam and spray bar? I was told by a Z mechanic if you used both you wold have very low oil pressure. 

I totally agree.. I don't think thats original.. if you do want that you need a bigger oilpump !!

 

 

In this pic i see a lot of wear on the left lobe.. it's eating the lobe.. not good.  

If you want to install a new camshaft, also check the rest!

[siteunseen]

14 hours ago, zclocks said:

So you had a internal oil cam and spray bar? I was told by a Z mechanic if you used both you wold have very low oil pressure. 

Ron

It had nothing on the gauge at idle but it would come up with the RPMs. I got an N42 with internal oiling cam installed just about as soon as I got the car. The motor was needing a rebuild of everything so I got started on that pretty quick.

I have one of those "change over" 280s. That odd N47 head and the sloped up rear deck. 

Oh yeah, I have the stuff to put together an E31 with a cut Nissan internal oiling cam and I'll use a spray bar. From all I read as long as I use a turbo pump it will be fine. The race guys did that back in the days. I run the turbo Melling pump on both my Zs now anyway. One has a spray bar and the other an oiling cam. The 240 with the spray bar pegs the oil pressure gauge when I'm driving. The 280 with the oiling cam just has good pressure. 

Edited May 22, 2021 by siteunseen

[ckurtz2]

Another update after a hard day's work. The Datsun has won again. Did a valve adjustment, some of the specs were crazy off. Mostly tight, but definitely not at what I set it to before. Redid the oiler gaskets with new proper ones. Realized that I didn't even have a gasket in the middle:( Anyways, fired it up, cold it was quieter, but once warm it was louder than hell from the valvetrain. I am thinking it's time for a new cam, internally oiled, and probably a hotter cam as well. So that's loss number 1

Number 2 I slapped on the potentiometer trick. Man that thing works like a charm to lean and richen the mixture. Quite a masterpiece, whoever came up with it. However, it did not fix the miss. The miss did go away when I had the potentiometer at about 3/4 rich. However, my eyes were watering from unburnt fuel, and it sounded like a vacuum out the back. With slightly more fuel I was able to get vacuum up to about 17 at idle, and it still ran fine. Still has a stumble though.

Are you positive that fuel injectors can be wired backwards with no ill effects? With good fuel pressure, vacuum, electronics tests, I really don't know what the miss could be caused by. I checked to see if the EGR thing was rotted through by plugging the holes, but nothing changed when I did. 

I am starting to think it is spark related. Is there a spark control module? Is it somehow possible for this to cause a miss? 

On a positive note the suspension, brakes, wheel hubs, shocks is almost completely out and ready to be cleaned and rebuilt. Just stuck on the spindle pins for now. 

[Patcon]

The stock EFI doesn't like performance camshafts

Also I doubt your camshaft is the main problem...

Edited May 23, 2021 by Patcon