Looks like # 23 from that link! Too lean and probably to far advanced. Just my 02.

 

Well I messed around with it some today...
I took the carb off, bench set everything, installed one jet size larger on the primaries (74), and two larger on the secondaries (83), put the carb back on. Started tuning the carb with the 4 corner idle mixture screws and got it as good as I think I could... and took her for a ride... It definitely did not break up as much as with the smaller jets, but still did a little bit... Brought it back home, pulled out a plug and its pictured below. Hard to see, but its close to before I made the changes, but a lil less speckels on the porcelain, and lil more color on top. Still looks way too lean to me. Im gonna try backing the timing down a few degress tomorrow morning and see what that does for me...

I wonder if some of my problems are coming from running such a hot plug?? its an AC Delco FR5LS, equivalents are Autolite 3928, Champion RC14YC.

 

The FR5LS is a 5 heat range plug, that should be fine on a zz4 engine with alum heads and 10-1 compression. Timing for that engine calls for 10* BTDC @ 800 and 32 total @ 4000. I"d be more tempted to run 33-34* total all in @ 2800 as long as you didn"t hear any detonation !!! Try some 76"s in the primaries and check them at 2500-3000 rpm

 

Ehh never got around to messing with the car today, other than looking at my timing marks I made with a white out brush... who knows what they are even at... I think it was at 10 and 32total actually, but the stock dampner is hard to read!
Im gonna clean them off, mark TDC, and go buy a dial timing light.
76/83 is actaully what the stock speed demon comes with and ran that combo before, but I think was still too lean... remember when I changed the plugs last time looking similiar. Im gonna try those again, and check the plugs now that I have an idea what the plugs should be looking like!
As far as the plugs, I do run the motor with nitrous occassionally, and really should be using a colder plug for that, so I went ahead and ordered an Autolite 3924 plugs last night with some other stuff from Summit... Ill try those out after I try the 76/83 jets if its still too rich... and if its still too rich with those jets and the 4 heat range plug, ill just keep jetting up.... LoL
Along with the 3924 plugs, I ordered a distributor re-curve kit ewith the weights/springs in addition to the adjustable vacuum can, so I can dial the tuning in 100% as well. And of course some more nitrous jets for the vette and my Dakota R/T

I wanna get this engine running optimally safe, so then I can start to tune it on nitrous as well.

 

Rule of thumb from A Real Motor Man The plug should be the color of choc milk. that plug is hitting /burning correctly.

 

Alright... I got to mess around with the car again this morning...
I threw in the 76 jets in front, and 85 in the secondaries...
When I had the carb off, I again bench set everything according to that BG carb tuning paper, and did it step by step...
At the same time, I also set the distributor to 10*, as it was definitely at 12* before. With the VAC can disconnected, it definitely can benefit from a re-curve kit since it doesnt come all-in till way up in the RPMs.
Anyway, I checked the plugs from the car sitting at idle for a few minutes, and came up with something like plug# 11 in the above link. And when I shut the car off at idle, it no longer "runs-on" Happy with that I supposed...
SO then I went and drove the car for about 10 minutes to clean the plugs off some, and just held it in first gear around 3000 RPMs, and turned the key off... and back to the "run-on" problem. Can this run-on be causing an erronous reading of the plugs!? When I pulled the plug it looked somewhat better... mostly like plug# 21 in that link.
I then did a WOT run all the way thru second gear and up to 4500 RPMs in third, shut it off, and more "run-on" Didnt even bother checking the plug cause of this.
So, can I get an accurate reading after the engine runs-on for sometimes as long as 5-10 seconds!? If not, how the hell do I cure this problem so I can tune the car, other than installing an o2 sensor?

 

That changes EVERYTHING..... I've never messed with NOS but from what I understand You need to be ALOT richer with even less timing!!

 

plus an even colder plug for nos !
I dont use nos so i can"t recommend a plug for that. Let the engine settle down to idle rpm, then immedetly shut it down, thats where your getting your run on from.

 

I can't see the color line on the ground strap??? The color if too far advanced is near the threads, retarded near the end where the spark jumps, you want it at the bend.
Idle is the ring above the threads and the center electrode and they should look a dry black.
I personally like the plugs.
WOT is the color ring right down in the plug and you will never see that.