280z 280z 78 Wont idle, Running Rich, out of ideas.

[Cyrillink]

1 hour ago, Dave WM said:

Guess the main question is why did it fail, yes the video seems conclusive. Hopefully its something like an improper torque sequence, else maybe a problem with the head, only way to know for sure is going to be to open it up and do a very close visual inspection.

I checked the head was way over torqued!  I am waiting on the timing chain tool and i will get cracking. 

 

1 hour ago, Zed Head said:

All it takes is one overheating and a head gasket can blow.  Maybe the first guy wasn't such an "A-hole" after all.  

Did the engine ever overheat before the car "broke"?  Never really said what the original problem was.

The other mech kept the for like a month and barely did anything. From what i understood as the story develops further. Never over heated. 

 

[siteunseen]

Put a framing square across the bottom of the head when you pull it to check flatness.

 

 

 

 

[Zed Head]

1 hour ago, Cyrillink said:

I checked the head was way over torqued! 

Could have been an attempt to fix the leaky head gasket.  Did you crack a bolt loose?  How do you know they were overtorqued?

Things don't fit - 30,000 original miles is barely broken in.  No reason for an HG to go.  Unless there was detonation, maybe from low octane fuel.  As I understand things though, that usually blows 5 or 6.  Check for signs of the head being off in the past.  Something's odd here.

 

[Cyrillink]

3 hours ago, Zed Head said:

Could have been an attempt to fix the leaky head gasket.  Did you crack a bolt loose?  How do you know they were overtorqued?

Things don't fit - 30,000 original miles is barely broken in.  No reason for an HG to go.  Unless there was detonation, maybe from low octane fuel.  As I understand things though, that usually blows 5 or 6.  Check for signs of the head being off in the past.  Something's odd here.

 

i agree with the odd story, i think something is not adding as well. The odometer says 30k m, body is also in a great condition. so here is the thing that throw me off, head inside is spotless no residue/stains what so ever. Also the cam lobs on the parts that are not worn look newish. Maybe a rebuild or an new engine? is there a vin on the motor?

Whatever, i know the issue and again thanks for allowing me to bounce some ideas of you. I will keep everyone posted on the Head gasket rebuild and how it comes out.

Hope this helps people out! a lot of good info. 

[Captain Obvious]

As I mentioned before, based on how clean everything is on the valve train, someone has been in there, and very recently. Way more recently than even 30K miles ago. Today's oils aren't going to keep things that clean, and certainly not 1978's oils.

I'm thinking someone had the head off right before your bought the car? That thing is cleaner on the inside than it is on the outside!

So what are the paint marks on the cam? Is that a "7" I can see in the one pic? And paint stripes on the tops of all the followers?

 

[Dave WM]

11 hours ago, Cyrillink said:

i agree with the odd story, i think something is not adding as well. The odometer says 30k m, body is also in a great condition. so here is the thing that throw me off, head inside is spotless no residue/stains what so ever. Also the cam lobs on the parts that are not worn look newish. Maybe a rebuild or an new engine? is there a vin on the motor?

Whatever, i know the issue and again thanks for allowing me to bounce some ideas of you. I will keep everyone posted on the Head gasket rebuild and how it comes out.

Hope this helps people out! a lot of good info. 

the engine serial number should be on the model tag inside the engine bay. there is a serial number for the body and a different one for the engine, both are listed on the tag.

[Zed Head]

Nissan stopped putting the engine number on the tag in 77 or 78.  It's not on a 78 for sure though.  

[Dave WM]

1 hour ago, Zed Head said:

Nissan stopped putting the engine number on the tag in 77 or 78.  It's not on a 78 for sure though.  

oh did not know that, did they start using the standard VIN numbers then?

Edited December 21, 2019 by Dave WM

[Zed Head]

The same style VIN.  They just stopped putting the engine serial number on the tag.  Don't know why.  I had a 76 and a 78, so have seen both.

[Cyrillink]

On 12/21/2019 at 2:31 PM, Dave WM said:

oh did not know that, did they start using the standard VIN numbers then?

 

On 12/21/2019 at 6:43 PM, Zed Head said:

The same style VIN.  They just stopped putting the engine serial number on the tag.  Don't know why.  I had a 76 and a 78, so have seen both.

Hey team wanted to wish everyone a happy new year and give some updates.

so I took apart the head, And like expected there was a hole in the gasketAnd like expected there was a hole in the gasket Between cylinder three and four

[siteunseen]

Show us a picture and maybe you'll figure out what caused it and how to prevent it from happening again.

[Cyrillink]

On 1/4/2020 at 12:42 PM, siteunseen said:

Show us a picture and maybe you'll figure out what caused it and how to prevent it from happening again.

 

On 12/20/2019 at 5:56 PM, Zed Head said:

Could have been an attempt to fix the leaky head gasket.  Did you crack a bolt loose?  How do you know they were overtorqued?

Things don't fit - 30,000 original miles is barely broken in.  No reason for an HG to go.  Unless there was detonation, maybe from low octane fuel.  As I understand things though, that usually blows 5 or 6.  Check for signs of the head being off in the past.  Something's odd here.

 

 

 

Hey Team,

Here are the pictures of the broken/burn gasket.

The GOOD: Took the day today and put the car back together. Replaced every hose that was cracked and looked older / shotty. Car started right up no pops no bangs nothing just ran. Was very very good to hear it start and run. So much better right of bat. No more blue smoke from the pipe.

The BAD: Still no Idle Have to the gas slightly to keep it at 800 - 1000. Pulled off the brake master vacuum hose connected the vacuum gauge... 5! (FACE PLAM)

Things done next: Took of PCV - Cleaned

Checked all the lashes - GOOD

Checked the sparks looking good all Cylinders are firing finally!

Tightened the Intake to about 25lb and proper tightened exhaust

Checked the Timing with a timing gun and found interesting stuff;

While it was set at zero (FACTORY Mark) on the distributor, on the timing was a little below 20 once i moved it all the way up i was able to get it to position 5. Car ran much better sound wise, BUT! i started getting black smoke! not much though.  probably F/A ratio idle screw needs adjusted changed. 

Thinking about moving a tooth down on a cam to fix timing.

 

Side Note Question: 

Any recommendations on a new coil to run with out the ballast resistor. Currently have ACCEL 8140C superstock 1.4 ohms on the primary. 

Thanks team. Really been enjoying build. Super different then my usual 300zx fixers.