Help me read this plug

[owdlvr]

So I've been getting HORRIBLE mileage on the rebirth of my 1776. Finally checked the fuel pressure out of my stock pump...8psi. Hmmm, guess that's the problem!

Parked the bug next to the lathe and worked out the right fuel pump rod length to get a steady 2psi out of the pump. After that I readjusted the idle mixture screws (50 jets) for high idle and sync'd the carbs. The plug photographed below is a new plug with less then 100miles on it, comes from Cylinder #2 (four shots of the same plug), after doing a 3600rpm pull up to Alice Lake from my house (Darren K knows the hill). Engine was shut down immediately and the plug pulled.

Thoughts on the plug? The photos are taken with flash, but I've balanced it out so it's not blowing out any coloring. The photo on the lower right was taken with a different camera after the plug rolled around on garage floor. The specs are dirt and blew right off. The shot does show the thread coloring and what I think is timing on the ground strap much better.

Any help or thoughts to assist me with tuning this engine would be much appreciated!



-Dave

[Darren]

Your still a bit rich by the looks of it... you also may need 1 step colder plug ..In that last picture (bottom right) it looks like the ground strap transition is around the corner towards the threads if im not mistaken.

did I send you this link?

http://www.empirenet.com/pkelley2/sparkplugreading.html

Cheers

[owdlvr]

These plugs are the NGK DR7EA, bumped up one heat range as you suggested from our last look. Perhaps I'll drop the 8's back in to compare the readings. I think I like your new plug reading link better then the last one. This was the previous one: http://www.4secondsflat.com/Spark_plug_reading.html

In hindsight, I should have run these plugs for a while longer before trying to read them. I think the color change you're seeing on the ground strap is actually the cadmium that burns off the NGKs, but I could be wrong!

-Dave

[Darren]

Try taking 4 Deg. of total timing out and see if that ground strap mark moves.

[jim martin]

i think Darrens on it .
rich at idle and mid and lean on the top end . before you put 8's in try pulling some timing .plugs are clean as well as not showing signs of overheating .
takle one jetting zone at a time .there is no sence driving the car for x amount of kms then deciding to pull a plug for wot jetting .get your idle jet figured out first . ring above threads should be at least grey to light grey and your close .then move on to top end .

[owdlvr]

Been about three weeks...I was out in Silver Star, and then Panorama coaching so I haven't been playing much.

Shortly after reading Darren's post I backed out the timing about 4deg, and sure enough the color change moved up the electrode. I swapped out the 50 idle jets for 45's, and took it up for a run the other night. Didn't see any change on the plugs, and the engine was dieseling on shut-down. Stopped for some thinking, and realized I had the accelerator circuit nuts adjusted for maximum spray...sure enough they were dripping at idle.

Tonight I backed both circuits off two turns at the nuts, black puff on acceleration is gone and they aren't dripping at idle. Forgot to pull and clean the plug before going up to Alice lake, but this is what the plug looked like after a 3800rpm pull:



The carbon is coming off the plug, after the photos I knocked off some 'sheets' easily from just inside the plug. I'm a little concerned about the spotting on the porcelain, and wonder if this is an issue? For what it's worth, can't pick it up with the naked eye even under magnification. Flash photography made it jump out.

I actually did two runs. The first run was with the timing set at about 25deg total advance (the current pulley is a b**** to read). I went up, determined that the timing was too advanced based on color change being right at hte bottom of the electrode, so went home dropped the timing to 20deg total advance. Idle was readjusted and then I took the run with the plug photographed above. On the first run the car has smooth power from about 2200rpm right through to 5k (where I lifted). I can run up to alice lake holding 3800rpm at about 3/4 throttle. On the second run, with the timing backed off. The power band doesn't start until 3,000rpm, I have to have my foot to the floor to hold 3800 up the hill and it's got a wicked 009 stumble when you initially push down the throttle. This hesitation is there from a standstill, and also partial throttle driving.

From the plug above, though, I would think I need to back off even more timing?


Fuzzy BB photo. 20deg on the left, 25deg of timing on the right.

I'm going to clean the plug, reinstall and do the run again in the morning.

...I'm thinking we're getting close enough to the GCVW show that perhaps I should sponsor a "Tune Dave's bug" contest. Free activity in Whistler for Two?

-Dave

[Bruce]

There is no way 20º is anywhere near right.  

At part throttle cruise, my timing is well over 40º BTDC.

Retarded timing causes runon when you turn the key off.

[owdlvr]

well that would explain my run-on when I turn the key off

So where do I go from here?

Just need to know what I fix first. Go after the timing or the jetting to start?

When I initially set the timing I set it to 30deg max advance around 3500rpm, and I've been backing it off due to the electrode reading since then. Distributor is a 009.

-Dave

[Bruce]

Why did you pick 30º initially?

Watch the advance of your dist with a tach.  Note where it reaches max advance.  It should be all in by about 2500 rpm.  3800 is for lame stock distributors.

[owdlvr]

Will re-adjust.

I seem to think 30deg was max advance out of my 009, but that was over a month ago!  Timing light is in the car, so I'll readjust before heading home.

-Dave

[Bruce]

I seem to think 30deg was max advance out of my 009,

?
The max timing is where you set it. Has nothing to do with the distributor.  Why did you pick 30º?

[Darren]

I would be putting a colder plug in ther and get some timing  back into it, you will burn the exhaust valves out a 20 Deg. total, 

Bruce I told him to use 30 Deg, bec that is usually a safe starting point..... 

Dave call me if you want to chat.