Still struggling with car at idle after 8 years

[dutchzcarguy]

Oh well.. remanufactured and REMANufactured.. there are a lot of differences.. I can't tell from that pic if it's any good.. missing a lot of parts.. sigh..

About the video.. can't tell as i never seen those testers at work.. (Never had a ignition problem ... i wonder why? )

Edited March 13, 2023 by dutchzcarguy

[jalexquijano]

On 3/12/2023 at 4:09 PM, Mark Maras said:

 Thanks for the video. Do the other plugs show the same intermittent spark?  I'm betting no.

Took the car out today car was misfire all the way. Guess problem has spread to the other spark plugs and car misfire all the way. I tried to step on the gas to see of by speeding the plugs would clear up but no luck. Guess its time to open this engine. Anyone has a different view?

[Yarb]

Well, You’ve fought this for along time now. I think it’s time to crack it open and take a look. Best of luck

[Mark Maras]

 I'd do another compression test (wide open throttle, all plugs out) before I opened it up. My thought is if it's got good (enough) compression, it's got to be fuel or spark.

[jalexquijano]

53 minutes ago, Mark Maras said:

 I'd do another compression test (wide open throttle, all plugs out) before I opened it up. My thought is if it's got good (enough) compression, it's got to be fuel or spark.

Another test?? This was done on March 5. 

[AK260]

Another test?? This was done on March 5. 

Well, if you’ve driven since march 5th then yes you should - lots could have changed! It takes no real time to do it and puts your mind at rest.

If the compression numbers vastly vary then you can suspect your head gasket and pull the head to see what is happening.

If not, then you can focus on electrics / ignition before moving onto other things.

If after 8 years and all the experimentation you haven’t found causes outside the engine, then perhaps it’s time to do something different and look inside the engine? Just a thought.

[dutchzcarguy]

As your engine is such a mistery i would do a cold and then a hot compression test on it  .. you may see some strange differences?  Also.. just a thought!  🙂

[Mark Maras]

@jalexquijano Was the engine running worse back in March and was it still fouling one plug? Now it seems to be worse. All but one plug shows fouling. Random question, does the engine use a lot of oil?

[emccallum]

I cant recall all of the tests you have done. FWIW, I had a z that was running poorly and after doing a bunch of stuff, it turned out that the dizzy shaft/bushing was worn and causing the point gap and rotor to float around. Easy enough to check for shaft play. 

[gundee]

20 hours ago, jalexquijano said:

Took the car out today car was misfire all the way. Guess problem has spread to the other spark plugs and car misfire all the way. I tried to step on the gas to see of by speeding the plugs would clear up but no luck. Guess its time to open this engine. Anyone has a different view?

It kind of looks as though the valve seals are not doing their job.

But I think you mentioned you replaced them. They can be tricky to seat properly.

[Patcon]

All kinds of possibilities. It's really unfortunate we haven't been able to sort this yet. I cant tell from the plugs if it's carbon or oil.

Mark might be right on it being fueling or spark.

It could also be valve seals or oil rings. Even with good compression you can have blow by. I think more compression testing is a waste of time. If the valve guides are badly worn the seals may not seal. This is a California Datsun engine after all!

I guess Jalex needs to pick a direction.

Fueling and ignition

or

Short block and head.

It's hard to know which way to go from such a long distance. Also there is the issue of finding competent people to help him.

Maybe you start with the cheapest option????

Maybe you just pull the head and have it gone through??? Valves, guides, seals, proper geometry...

It's problematic that the cars are so rare where he's at. Otherwise he could try different parts to help diagnose..

 

[emccallum]

Yep, my compression numbers were good but oil rings were bad. Fouled plugs and lots of smoke. You have to know that ignition is good and carbs arent too rich.

Does it smoke?