Timing Issue

[siteunseen]

[chiefmd]

I started with Zed Head process and decided to work on the idle issue first. Checked the AAR thru ECU for 12V, all good. I pulled the AAR and looked inside and there is about a 1/16" opening, I thought should be open about halfway when cold, right or wrong?

Situnseen - I do have a vacumm gauge and will perform the check. Thanks for the article on installing shaft.

[siteunseen]

I think halfway cold is right. Put it in the freezer and see then hot water. Your cold might be 80 outside. It's  92 here.

It's always warmer here so my AAR is useless. 

Sorry I haven't read the whole thread but surely you've turned the idle adjustment spring up top after the throttle body? Another thought, is your throttle body plate closing completely? I've had to clean my with lacquer thinner and a toothbrush. They get gunky.

Edited May 23, 2019 by siteunseen

[Zed Head]

12 minutes ago, chiefmd said:

I started with Zed Head process and decided to work on the idle issue first. Checked the AAR thru ECU for 12V, all good. I pulled the AAR and looked inside and there is about a 1/16" opening, I thought should be open about halfway when cold, right or wrong?

Situnseen - I do have a vacumm gauge and will perform the check. Thanks for the article on installing shaft.

The AAR does the same thing as the idle adjustment screw.  You could just open up the idle adjustment screw to see if it starts and holds idle.  If it works then the idle speed will slowly increase the engine warms up.  It will be a good clue about the problem though.

[chiefmd]

Well I placed it in the freezer for a few hours and then in hot water. Here are the results. When I took it out of the freezer is was about halfway open and after the hot water it was fully closed. So I guess it is functioning as it should. On to the next item.

[chiefmd]

Zed Head- I checked my old distributor against the rebuilt one and there is about 1 1/2 dash mark difference which would be about 6 degrees according to the picture you supplied.

The new distributor is set on the second dash mark from the top (as shown in you picture) while the old one was about 3 1/2 marks. Should I go ahead a reset to were the old one was (3 1/2 marks)?

Do you think that would be the difference of 10 btdc and 15 btdc?

[Zed Head]

The timing light tells you what your timing is.  It is what the light says it is.  Not sure that fiddling with the distributor will help things unless you want to run with 20 degrees initial timing.  That's pretty high.  You could easily end up at 40 degrees at 2500 RPM which your engine might not like.  Some of the 280Z distributors even have 11 degree weights, for a total of 22 degrees on top of initial.

I don't really know what's happening with your problem.  I'm still leaning toward vacuum leak.  The Aussie Home Built Z guy just posted a video about having to run very high advance numbers for timing then finding out that his intake manifold wasn't bolted down.  Big leakage.  I think it's in his "Dyno day" video.  Once he fixed the vacuum leak he got back to normal.

[Zed Head]

Pretty sure he describes it in the what will it make video.  Tried to find where he talked about timing but my computer sucks for videos.

https://www.classiczcars.com/forums/topic/58542-home-built-z-full-video-build/?&page=27#comments

 

[chiefmd]

I have been following Jeff's videos. I will go review that video again. I do know that I have the washers installed and all was torqued to specs. Today I did take a vacuum reading from intake manifold and surprise surprise 3-5 lbs and 10 when reved. Not good

[Zed Head]

1 hour ago, chiefmd said:

Today I did take a vacuum reading from intake manifold and surprise surprise 3-5 lbs and 10 when reved. Not good

I think that lower vacuum when revving is a sign of a leak.  At higher air flow the leak gets overpowered.

Don't forget the EGR system.  It's a known problem.

[siteunseen]

I had a problem with my EGR.  You take a handheld mirror and look under the intake manifold closest to the windshield.  The coupling hooks there, mine was loose for who knows how long and rotted out my EGR chamber? I think it's called.

This is after I replaced everything but gives you an idea of what I'm talking about.

Another thing that happened to me, and me only apparently 'cause I'ma stupid sometimes, I put the valve cover gasket on upside down and created a small opening above the thermostat housing.  They have a straight side and mine was opposite.  I know that's not your leak but it's something to look at.

 

[siteunseen]

Hard to see but it's a little different than the other side.  One side is a little shorter than the other.  Good luck!