Building A L28 (Na)

[esmit208]

On Tuesday, May 09, 2017 at 1:12 AM, TheCrazySwede said:

Awesome! Did you paint those yourself? I have 45's

Yes but it just my own personalization.

[TheCrazySwede]

So the Z no longer has electrical issues!

I ended up ditching my current harness and re-modified a harness out of a 73 240z and used that. Works great and no longer giving me issues! Also installed some led bulbs in the car and some HID's while I was at it.

I' currently facing an odd issue...

During idle, Cyl4 and 5 don't fire. I checked for spark and compression - both give positive results. Turning the idle mixture screws don't do anything, either. Something get stuck, possibly? Under load I believe the engine runs on all six, but definitely not under idle (disconnected Cyl4 and 5 serves no changes to the idle.)

Anyone have any tips as to why? The only thing I can think of is maybe the needles getting something stuff in there...

I tried spraying starter fluid into those carbs and didn't get any change in idle behavior - but I do get that from any other carbs.

[sweatybetty]

edit delete

Edited May 23, 2017 by sweatybetty

[TheCrazySwede]

Ok, it's been a while since I gave an update, so here it goes!

Every wire in the car, from front to back, has been redone, replaced or discarded. The car runs on what is needed. No heater, no fan controls, no radio, no antenna switch - not even the fuel light was spared. The car runs on only what's needed, nothing more and nothing less. 

 

The issue with the idle and pilot jets is resolved, too. Idles and runs on all six cylinders now! I'm not sure what did it, but I replaced my filter, cleaned my tank, cleaned out the carbs as best as I could and messed around with the idle mixture - and eventually it worked!

 

I've spent many hours now diving into every piece of literature I can find on DCOE carburetors and I've surely learned a lot to the point where I feel very comfortable working on these guys. What I couldn't find much on was what parts of the DCOE family (Weber, Mikuni, OER, Solex, etc.) is interchangeable - specifically talking about jets.

What I learned is that Weber idle jets work as long as you get the appropriate seats for them. Mikuni Air Correctors work on these carburetors, too, and fit right into the emulsion tube. The mains, however, only seem to fit with OER ones. I went through a lot of different setups to find something that works for this engine and so far the perfect recipe seems to be:

Mains: 135

Air: 160

Idle: 65(OER)/65F9(Weber)

I am currently running 62.5 pilots, but it's a tad bit too lean when cruising. i've tried 70F8's and 70F9's and they're both too rich. My guess is that 65's should fit in perfectly, but they're still on their way from Japan since I'm going with the OER one. The F9 designation on Webers is the same as the OER.

 

I also got a wideband hooked up now so I can get proper readings on this thing. At idle I'm currently sitting at 12.7-13 AFR, it goes up to 14 when cruising under 2kRPM (should richen up a bit with the 65's) and I get in the mid 12's at WOT, which seems to be the sweetspot for this engine.