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Discussion Starter #1
Hello again all,

I finally got my starter issue sorted out. Initially, the car wouldn't start after it got warm, but it turned out to be the hot exhaust dumping out of the open headers onto the starter motor. A little heat wrap solved that solution.

I recently installed a new edebrock 1406 in place of my old 1406 and the car runs better than ever! Using my dwell tach, I adjusted the idle mixture screws to get max rpm. Now the car takes off smoothly and doesn't sputter or bog anywhere through the rpm. It has never run so well! However, now I am concerned that I am running too lean. I pulled the #1 plug after driving the car for 20 minutes straight, and the filament is white and the electrode looks clean as a whistle. Is this still ok considering that I'm not experiencing any hesitation or other probs? Or do I need to drive the car around for an extended period of time before trying to diagnose the plugs? I think that spending the last several months rebuilding a motorcycle has really affected my car knowledge...looks like it might be time to find a garage in Nashville so I can work on the car more often! I'm open to any suggestions. For reference, the plugs are new and the engine is a 351W with tremec TKO.

thanks,
Jeff
 

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How does it pull in high gear (direct drive) at WOT? If it doesn't nose over or detonate, you're likely OK. You can bump the jets up two steps and compare.

Best way to run the plugs is to do a WOT pass and shut off clean, then pull them. On the street, keep idling to a minimun prior to shut down.
 

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I have Holley 600Vac with 612 main jets, pretty lean. Plugs are white, I could sell two year old plugs as new. I think that most people run unnecessary rich. Ok, I use 94 gas, DUI distributor that has enough power to burn lean mixture and 160 thermostat, those things keep the detonation away even with 16/40 degrees advance. I hear detonation when acclerating at low gear against a hill, about twice a year.

Yesterday, I used 650DP with much richer set up and picked up only 6 hp 5100-5300rpm.

I think that many engine builders are nowadays running their engines much leaner than before.
 

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Pat's advice is right on the money. If you're looking at the plugs to judge the lean/rich (air fuel ratio basically),
a WOT run and immediate shut down is the correct method.

Info:

http://www.dragstuff.com/techarticles/how-to-read-plugs.html

You can draw some very general conclusions after doing some normal driving. You need to be able to look down inside at the base of the porcelain. You'll see a carbon ring encircling the porcelain. The size and height of the ring can give you some idea of how the a/f is.

I use one of these things.

If you're not experiencing any surges or stumbles, I'd wait to get a sniffer on it to see how the a/f ratio really looks.
 

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Discussion Starter #6
The engine still has not been fully broken in, so I'm a little hesitant to do a WOT chop. Perhaps I will just pay a couple of bucks and get it sniffed because I really don't feel like putting a hole in one my pistons.

It's too bad that I don't have one carb per cylinder. On my bike, I just purchased a tool called Carb Tune (big in the UK) that allows you to screw in a spark plug with a glass filament and then tune the engine to achieve a stoichiometric blue flame throughout the rpm range. I know that they make it for cars too, but I'd be reluctant to gauge the accuracy.

thanks again everyone for the input,

Jeff
 

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The engine still has not been fully broken in, so I'm a little hesitant to do a WOT chop.....I just purchased a tool called Carb Tune (big in the UK) that allows you to screw in a spark plug with a glass filament and then tune the engine to achieve a stoichiometric blue flame throughout the rpm range. I know that they make it for cars too, but I'd be reluctant to gauge the accuracy......
Jeff
I can understand that. ;)

I've got the tool you're talking about. Called "Color Tune". As to accuracy, David Vizard mentions in one of his books that he uses the "Color Tune" to calibrate some of his other equipment.

They aren't that expensive and are a pretty cool unit. It's interesting to be able to see the combustion process going on in the chamber.
 
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