240Z WILL NOT run right

[Captain Obvious]

3 minutes ago, inline6 said:

If absolute accuracy matters to you, the spade for the wire hook up points upwards instead of to the side originally.

Like this?

[BoldUlysses]

^Thanks for that.  You'd be surprised at how hard it is to find a pic of a stock distributor's wiring online.

[Captain Obvious]

Glad to help. So comparing your pic to what I have here, there are some other differences. I'm not sure which is correct, but the wiring inside my distributor is a little different than yours.

On the inside of mine, the ground wire went to the other side of the points than yours, and I've got this yellow wire on the high side of the points. Functionally it doesn't matter where the ground wire goes, and I'm guessing that my yellow wire was put in by a previous owner.

Here's what I got. Input on originality appreciated:

 

[Captain Obvious]

i kinda like the way your ground wire runs to the other side of the points. I wasn't completely comfortable with the way they were sharing a slotted hole on the points with the big washer AND the electrical connection.

After seeing your pics, I'm thinking that wire should go to the other points screw like you have yours.

[BoldUlysses]

I thought about securing the left end of the wire to the side you have it, but I was a little concerned with the wire being pulled taut when the timing is advanced.  Electrically it doesn't make a difference since they both connect to the same big plate.

[inline6]

1 hour ago, Captain Obvious said:

Like this?

I mean for the wire from the harness, not the capacitor wire. 

Like this:

https://jdm-car-parts.com/products/euro-spec-distributor-for-datsun-240z-w-manual-transmission-nos

and this:

Edited September 12 by inline6

[inline6]

2 hours ago, BoldUlysses said:

Awesome, thanks.  I mainly wanted to make sure I had hooked the condenser up correctly.  Dielectric grease OK for the cam?

Wasn't sure, so I did a search and found this 🙂 

"Yes, dielectric grease can be used on a distributor cam. Silicone dielectric grease can be used to lubricate the cam lobe rubbing block contact on a distributor, and it can also be used to seal electrical connections and ensure conductivity. Some recommend re-lubing the cam lobe rubbing block contact every 3,000 miles."

Edited September 12 by inline6

[Zed Head]

Might as well check the condenser before you get too far along.  It should have "OL" from the wire to the condenser body metal.  No continuity.  You can also measure capacitance if you have the right meter but it's not commonly done.

And .020 is your point gap.  It should determine the dwell on a new cam but a dwell measurement is more precise.  It's measured in degrees with a dwell meter.  As the cam wears the dwell could change.

Mechanical ignition systems are more complex than they seem.  Kind of amazing that they work like they do at high RPM.

Here's a pretty good article from Pertronix.

https://pertronixbrands.com/blogs/product-higlights/understanding-ignition-dwell?srsltid=AfmBOooVjLx4762Zc7UGTaiEOiTUuhwututQ4aKVsDB2ZJPHPywx_gMZ

[Captain Obvious]

10 hours ago, inline6 said:

I mean for the wire from the harness, not the capacitor wire. Like this:

https://jdm-car-parts.com/products/euro-spec-distributor-for-datsun-240z-w-manual-transmission-nos

Hmmm... So on my and BoldUlysses distributors, the electrical connection to the coil sticks out sideways instead of upwards towards the cap. I had tried before to swing the condenser connection to the side (instead of from the bottom), but I changed my mind because of the poor fitment. It got in the way of the other spade to the coil.

So the spade to the coil should point upwards instead of sideways? As shown on the euro distributor you linked to:

[BoldUlysses]

41 minutes ago, Captain Obvious said:

Hmmm... So on my and BoldUlysses distributors, the electrical connection to the coil sticks out sideways instead of upwards towards the cap.

You can orient the little metal tab whichever way you want; just loosen the screw & rotate it 90°.  It may have originally been oriented up when I had the points on before; I don't remember.  To the side just kind of made sense to me this time around, given the direction the ignition wire comes from.

[Captain Obvious]

10 hours ago, BoldUlysses said:

To the side just kind of made sense to me this time around, given the direction the ignition wire comes from.

Me too. The coil tab to the side made sense to me as well. But orienting both the connections in the same position didn't work well.

In any event, it's really not a big deal. Thanks for bringing up the questions so I could tag along for the ride!  

[BoldUlysses]

OK report after the points reinstallation:  No change.  I guess maybe it runs a little better.  I dunno.

It runs alright on initial startup, but as the engine warms up, it gradually devolves to this:

(speedometer is currently disconnected)

Started off in 2nd gear and slipped the clutch to get it moving.  It idles fine, but bucks and backfires at anything over a light load.  Undriveable.

• Drawing fuel from the auxiliary tank (no filter) in front of the rad support through a known-good pump.  3-5 psi idle.
• 17° BTDC @ 750 rpm.
• Float bowls lids nice and snug.
• Carbs sync'd with Uni-Syn, ~2.5 turns down on the screws.
• Float bowls wet-set to 21mm front, 19mm rear.
• I capped off the PCV & brake booster ports on the balance tube just in case there was a vacuum leak.  No change.
• Misted carb cleaner around the carbs & intake.  No change.

I'm totally stumped, guys.  Really wanted to take it to Cars & Coffee on Sunday, but I guess that's not happening.