I am in the process of tuning my carbs. I had been dealing with some significant rich running issues that I posted in a previous post. That issue is resolved. Now, I am able to drive the car however it seems to hesitate at cruising speeds (2500k rpm). Idle seems a little rough.

I am a novice at reading spark plugs. I am looking for opinions on this plug. The other plugs look the same except the white on the electrode only goes a little past the curve.

I should note that the timing was a bit too advance and has been dialed back a slight bit.

My guess- little too rich, too hot of spark plug and timing too advanced.


Setup info-
Dual weber 40 idf- recently sync'd
idle jet- 60
mains-145
air correction jets- 200
emulsion tubes- f11
vents 32
Spark Plugs- NGK BP7ES
Engine- 2.27l

I should also note that I have a lot of spark plugs laying around. Doe anybody know if a NGK BP8ES is hotter old colder than BP7ES (think its colder).

Way to lean!
engine specs?

http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html

Here's a good photo reference
Mike

For my future reference- what makes you think too lean? I thought maybe a little rich because I had some black soot on the base ring.

Engine Specs-
2.27l-recently rebuilt by local porsche builder using parts I provided.
78.5mm crank
96mm jugs
2.0l heads
not sure of cam- told by PO was "a fairly aggressive webcam for carbs" whatever that means. I really should have checked prior to assembly.
MSD 6al
MSD blaster 2 coil
bosch 050 dizzy

What do you think I should change?

I realize that it may sound dumb that I am asking what I should change if I am to lean. The reason that I said that was because I am already at an idle jet of 60 which I thought was getting on the high side. I wasn't sure if I should make a different change first- such as mains (doesn't make sense to me that mains would help much).

Any opinions on whether the NGK BP7ES are the correct plugs or not?

I am using nearly the same jetting on a 2056.

I think that your carbs may simply be too small. You may need to go up to 44s instead of 40s.

Also, are those plugs from idle, or from driving range? If the car idled at all before you pulled the plugs out, they are only showing you how your idle is. To see what your burn is under load, you have to turn off the engine while under load. Like going down the freeway, pull into a rest stop ramp, and turning off the motor while you are still moving under power, and seeing what the plugs look like.

Zach

I was wondering about that also. I have a set of larger venturis. I may put those in to see what happens.

I have read a few posts that suggest that 40idfs may be ok for my setup. It may be wishful thinking because I really don't want to buy a new set of carbs.

Here's a "how to" on webers I found with a quick search, DCOE is the sidedraft version of a IDF.
http://www.teglerizer.com/dcoe/webertune.htm
40mm are getting borderline on a 2270 but they should work fine, all kinds of guys run 40's on 3.0 /6"s.
You should run only about 28* advance and try the colder plug.

Pop of your pump and the cam grind is stamped around the cam oil pump drive.

Man I love tuning with a wide band, I hate the "old school" method now. The real nice thing about a WB is you know if you're lean instantly.

Larger carbs are probably NOT the answer, especially since you are running 32 venturis.

Before I did anything, I'd get an assortment of larger mains and smaller air correctors.

Just for starters I'd try 180 airs, and then maybe 160 mains.

The plug even shows that the timing was too advanced.. The yellowish residue on the electrode tells you where you're timing is at. Spot-on timing is considered right at the curve (90deg.) of the electrode. Above it is advanced, below it is retarded timing..

Awesome- excellent info!

.Your / the plug gap appears to be excessive...to big...., the fuel air ratio is lean...the engine is running lean.....go down on the air correction jet as a starting point ..one jet size.........and the accelator pump jet size and fuel volume might need to be richened up......Check the plug gap FIRST.... .028 ths.....What oil are you using?...dino or synthetic?...how new is this engine? is it broken in yet?...rings seated?...

Reading plugs from engines with unleaded fuel is difficult..

I have the plug gap set at .40. I read that somewhere around .40 was correct when using a MSD unit. I can change it an see what happens.

I have th floats set up at 10.5 with the gasket in place.

I am using 20-50 dino oil.

My engine is very new. It has approx 200 miles on it. I followed a break in procedure but I cannot really remember the exact procedure- it was 6 mo ago or so. How do I tell if the rings are seated?

You can get Innovate LM-1's used all day long for $250 or less. It's the best investment you will make... Typically you jet by the size of the venturi and not the size of the engine. That being said there are many variables including but not limited to:

* Fuel (% of ethanol and other oxygenating additives)
* Engine efficency
* Exhaust System (see above)

Like Jake said, looking at plugs with todays modern fuels is extremely difficult. Get it on a wide band and when in doubt jet on the rich side. I think your plug gaps are fine with an MSD. I run .045" with a Mallory 6AL and a Bosch Blue Coil.

Correct me if I'm wrong Jake, but I was taught that with unleaded fuel, you read the ceramic insulator for mixture...

Well with only 200 miles on the engine the rings are not broken in or seated completely yet..( generally after 500 to 1000 miles the rings seat.)(variation due to cylinder wall finish)..The reason I suggested checking the plug GAP is that , with a Lean mixture, and excessive plug GAP you can have misfires/and detonation....which might/or could be the hesitation you mentioned...I asked about dino/synthetic oil.....plug readings with synthetic oil ESPECIALLY on a new engine W/O seated rings can be trickey. You do not have that as a diagonistic problem...CHECK all four spark plugs, if apperance is same , assume float level is correct.
....Reduce the air correction jet size to richen up the fuel mixture., set timing at 27 degrees BTDC total advance.(for now)....YOU NEED MORE HEAT in the engine before the rings are going to seat properly. DO NOT "drive it like you stole it" as some idiots may have suggested as a break in technique. Keep the revs at or below 4000 rpms., make sure you have FRESH uncontaminated gas....go on 15/20 minute trips. shut down and let cool off. The heat cycling will promote proper seating of the total engine components "warping" seasoning of the engine.( it'll last a hell of a lot longer)...Check valve lash at 500 miles.....I look forward to your progress reports. Murray.