Zmanco Posted August 18, 2006 Share Posted August 18, 2006 I have triple weber 40's on my L28 w/flat top pistons, 6:1 header, and 284/284 .480" lift cam. I've finally got my jetting to the point where it drives great, almost perfect. There are few minor nits but given it's completely livable now, I figured I'd check my plugs to see what they look like: The coloring in the pictures isn't as accurate as I would like, but you can see that there's a lot of soot making me think I'm too rich. However, I just went up to the 50F9 idle jets since the smaller ones were too lean below 3k. My mains are 130 and I'm wondering if I should try going to down to 125? That seems kind of small, but that's all I can think of. Any other suggestions? Edit: Forgot to mention I live at 6000 feet. Quote Link to comment Share on other sites More sharing options...
slownrusty Posted August 18, 2006 Share Posted August 18, 2006 Looks rich, but reading spark plugs is a science. EGT gauge or an AFR gauge is the only real way to know. when I was running sidedrafts I installed an EGT gauge for tunning purposes. If you run down the 'Springs we can do runs and log it on my LM1, if you like. Yasin Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted August 18, 2006 Share Posted August 18, 2006 or to Centennial and we can check it out with my LC-1 =) my wideband was the best money ever spent.. but those plugs are fouled to all hell Daniel.. LoL.. might wanna lean it out a bit Quote Link to comment Share on other sites More sharing options...
Zmanco Posted August 18, 2006 Author Share Posted August 18, 2006 I forgot to mention that I have a narrow band O2 sensor on it, which so far has been very helpful in making the carbs very drivable. Of course, I don't know how rich I am, as the plugs show I know I can't go any leaner on the idle jets as I've already tried that, so maybe I'll just try one size down on the mains. Thank goodness there's a guy on ebay with reasonably priced jets. Question: can either of your widebands be installed temporarily? How would that be done? Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted August 18, 2006 Share Posted August 18, 2006 You'll need to go wideband, those jets are so fouled it isn't funny. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted August 18, 2006 Author Share Posted August 18, 2006 You'll need to go wideband, those jets are so fouled it isn't funny.I noticed that my mileage dropped 2-3 mpg when I switched to the webers. While I didn't expect it to improve, I was surprised that it dropped that much. I had just assumed it was because I was always heavy into the throttle to hear them sing Just thinking about this further, I wonder if I should be going up in size on the air correctors due to my altitude? I'm currently at 200. Anyone with Webers at altitude have any thoughts? Quote Link to comment Share on other sites More sharing options...
slownrusty Posted August 22, 2006 Share Posted August 22, 2006 Mine can be temporarily mounted. Like so: Yasin Quote Link to comment Share on other sites More sharing options...
CArFAn Posted August 22, 2006 Share Posted August 22, 2006 found this thought it may help http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 22, 2006 Share Posted August 22, 2006 First thing is what you were doing before pulling the plugs. The way to read plugs properly is to go WOT, then kill the engine and step on the clutch at a given rpm. Pull over and read the plugs right there on the side of the road. Then as mentioned, you have to actually know how to read plugs, and hardly anyone does. The easiest and cheapest way to get a good idea of what is going on is to weld an O2 bung into your exhaust collector and run a single wire narrowband O2 to a voltmeter inside the car. Get a good quality narrowband O2 (I used Bosch) and you'll get repeatable, accurate results. Shoot for about .8V on the voltmeter. Wideband is better, but narrowband will get you close, and it only costs ~$30 assuming you have to buy the O2, the voltmeter, and the wire to connect it all up. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted August 22, 2006 Author Share Posted August 22, 2006 found this thought it may help http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html Thanks, that's the best chart I've seen since they show multiple examples of each. My O2 setup is just what you suggested, and it was invaluable to get rid of the flat spot transitioning to the mains. I've gone ahead and ordred smaller mains, and larger air correctors as well. I'm hoping/expecting that some combination will get them much closer to neutral. Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted August 23, 2006 Share Posted August 23, 2006 All running a car at WOT and then reading the plugs does it tell you what your WOT rich/lean condition is. Doesn't tell you anything about part throttle which is where you drive 99% of the time. The wideband is the way to go. Quote Link to comment Share on other sites More sharing options...
John Scott Posted August 23, 2006 Share Posted August 23, 2006 ....and if you have a lump bumpy cam and then putt putt around for weeks you'll have perma black plugs like mine always look, even when I'm jetted lean. In other words, with old plugs, it would take a lot of WOT to get an accurate read. Better to start with a fresh set...or better yet what everyone else has already said about WB AFR. BTW, knowing your credentials, you could probably "Mcguyver" one of these in a few minutes from a game boy and a watch spring John Quote Link to comment Share on other sites More sharing options...
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