L28E TDC Verification

[Tony D]

Ah, OK, I can see them on the laptop... you're right, the OP said:

 

"Here is where it sits now, explain to me what the engine assembler was thinking and how it can all be adjusted back to OEM specs."

 

The one photo shows the notch advanced, and the other photo shows the typical 'Set it to #3 for Race' mythological position....

 

The answer is partially in the last sentence and:

 

"Set it back to Notch #1"

 

Too bad it took so long for someone to look at the basics and SEE them in the photos! (I should log on my laptop and not my iPhone so much!)

[AdreView]

Ah, OK, I can see them on the laptop... you're right, the OP said:

 

"Here is where it sits now, explain to me what the engine assembler was thinking and how it can all be adjusted back to OEM specs."

 

The one photo shows the notch advanced, and the other photo shows the typical 'Set it to #3 for Race' mythological position....

 

The answer is partially in the last sentence and:

 

"Set it back to Notch #1"

 

Too bad it took so long for someone to look at the basics and SEE them in the photos! (I should log on my laptop and not my iPhone so much!)

 

Tony, so the question is do I just stick with the current #3 "more oomph, because racecar" setting and go ahead per your instructions and adjust spark timing?

 

Or...set the sprocket back to the #1 OEM spec setting and then go ahead with spark timing adjustment?

Edited April 7, 2014 by AdreView

[Xnke]

Set it back where it belongs!

[seattlejester]

I followed the "how to rebuild your datsun OHC" book. I think I ended up with position two lining up the best with the timing mark for my particular engine. So as Xnke says, put it back to where the timing marks line up. Just make sure you use a good timing chain tensioner tool, if the chain falls you are going to have to take the front timing cover off, and that can be a real pain.

[AdreView]

Having not touched the cam sprocket setting from position #3 yet, these are the results after the hot valve adjustment and spark timing adjustment.  Initially, the spark timing was reading at 20 degrees BTDC, I adjusted it to the factory 10 degrees BTDC.

 

This is a warm start at about 800rpms per the factory tach (which I know is not very accurate):

http://youtu.be/R702A_RQsJU

 

 

Here is the fuel response:

 

http://youtu.be/Tqqc5CK553U

 

 

AFM and vacuum response:

 

http://youtu.be/BRSdOKLuWTI

 

 

This is what all the plugs across the board looked like without driving the car, keep in mind the richness they faced prior to valve adjustment (I did clean them off, but the rich fuel lays it's mark well), hence the black on the insulator tip:

 

 

 

 

 

Now I believe I need to get the fuel tank cleaned and sealed internally and also get the AFM calibrated for today's fuel.  I believe adding a A/F gauge and sensor will aid in further tuning.  I still have to sort out the throttle valve switch as my pops couldn't hold a steady 1400 rpms so I could verify release of the right side post contact.

 

Tony, what else may I be missing here or next steps?

Edited April 8, 2014 by AdreView

[Xnke]

Set the cam timing back where it belongs!

 

if it's not right, then you will not be able to correctly set the other functions you are looking at. Today's fuel burns at a 14.4 stoich, compared to straight gas at 14.7 stoich. That assumes 15% ethanol content, which may or may not be the case.

 

Set the AFM per factory spec, set the timing to factory spec, set the cam to factory spec, THEN start wondering where to make mods.

Edited April 9, 2014 by Xnke

[TimZ]

if it's not right, then you will not be able to correctly set the other functions you are looking at. Today's fuel burns at a 14.4 stoich, compared to straight gas at 14.7 stoich. That assumes 15% ethanol content, which may or may not be the case.

 

Careful - Wideband EGO sensors generally measure lambda (1.0 at stoich) and multiply by 14.7 to get AFR, assuming that everybody runs straight gasoline.  So unless your wideband allows you to set a different fuel type it will read 14.7 at stoich regardless of what fuel you are running.

[Xnke]

Even the LC-1, the cheapest thing going, allows you to choose that...

[TimZ]

Even the LC-1, the cheapest thing going, allows you to choose that...

Yes it does, but only if you know that you need to do it.  Most don't.  That is why I'm mentioning it.

 

If, like 99.9% of wideband users do, you took your off-the-shelf wideband and tuned assuming 14.4 was stoich "because you have E15", you would _not_ end up with the mixture that you thought you tuned to.  Granted, in this case you'd only be a few percent rich across the board, but just saying that you need to tune for 14.4 without explaining the subtle but important details just muddies the water, and is very likely to make things less accurate, rather than more.

Edited April 10, 2014 by TimZ

[AdreView]

Set the cam timing back where it belongs!

 

if it's not right, then you will not be able to correctly set the other functions you are looking at. Today's fuel burns at a 14.4 stoich, compared to straight gas at 14.7 stoich. That assumes 15% ethanol content, which may or may not be the case.

 

Set the AFM per factory spec, set the timing to factory spec, set the cam to factory spec, THEN start wondering where to make mods.

 

Waiting on delivery of a timing chain holding tool before I can proceed.

[Tony D]

Someone actually 'tunes' to 14,7?

[TimZ]

Someone actually 'tunes' to 14,7?

Across the board - isn't that ideal?  ;P

[AdreView]

Received the timing chain tool, set the cam sprocket to position #1 and here are the results:

 

 

 

Now I know that upon the rebuild they quite possibly used a new chain as you can see.