Running Lean?

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64 SRT8 Dart

64 SRT8 Dart

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Ok well the 318 is in the Valiant and am wondering if the primaries are too lean.
I'm sure the secondaries are fat enough as when I'm hammering on it I can smell that its a little rich.

Carb is an old 650 SB DP. 65prim 87 sec jets.
Cam is a Comp XE268.
Plugs are Autolite 65.

They look really clean to me.

What do you think?
 
What heat range is that plug? does it ping or rattle? bog or anything like that? seems to look to me.
 
Looks rich and undertimed to me (initial timing anyway). To be honest you can't tell much unless you cut the engine and pull the plug for a certain condition. If you want to know how it's doing at WOT then after a pull you slow down and cut the engine off as quickly (safely) as possible. Same goes with cruising conditions. Cruise at a certain speed for a couple minutes, then get then engine turned off as soon as possible to preserve the reading. The plug in the pictures looks to have quite a bit of idle time on it so that's all you can read. It's also helpful to start with a new plug.

All that said, it looks ok to me. Sure it looks like you could clean up your idle and maybe give it more timing, but not bad. What is the timing set at anyway? You running the vacuum advance? Did you clean the plug at all before taking the pictures?
 
I have the vacuum advanced un hooked and was going to run it at around 32* total. Not sure what would work best with that cam but as of right now, it's set by ear.

I ran the engine up to 2000 and advanced it to the point that it brought the rpm up then start to load the engine then backed it down a bit.
I know on a fresh motor that's a nono but I don't have a timing light and that's just what i've known to do for a temporary setting. Maybe I backed it down too much.
 
th


hope it helps
 
Ok, so I'm actually prob running rich in the primaries and lean in the secondary.

I really really need to get a timing light on this thing.:violent1:
 
That picture, though a good general reference, is wrong on one thing. The part that says "lean wot" is not correct and you cannot tell by looking at the top of the porcelin. To properly read wot you must look deep down inside the plug where the porcelin meets the bottom. There will be a marking commonly called the fuel ring that will tell you what's realy going on. The rest of the porcelin could be stone white but the engine could still be running rich.
 
Btw that's a huge jet spread on your carb. I don't know the stock jetting for your particular carb, but it's possible you're either slighly lean on the primaries, or over rich while on the secondaries, or both.

A general rule of thumb for a carb that has a powervalve in the primaries and no powervalve in the secondaries is 8-12 jet sizes. I'm thinking there's something wrong with a 22 jet spread.
 
Yep, that's a big jet spread. That's a big jet you have on the sec side. I think a lot of the 650 DPs had an OOTB jetting around 67 pri, 76 sec.
 
You need a wideband A/F guage, then it would tell you through the entire throttle range if you are lean or rich.
Makes it really easy to know where and what to change if you can't feel it in the car.
 
64 SRT8 Dart said:
Even on a spread bore?
Click to expand...

Spread bore carbs do run a wider jet spread than a square bore. What is the list # on your carb? I remember a 6210 being one of the 650 spread bore Holley's and I just looked in my Holley book and see it came with 60's in the primary side and 83's in the sec side so it sounds like yours might be jetted richer than normal but IMO your plugs don't look too bad, just a little rich at idle. Not having enough initial timing can also have an effect on that as well as the adjustments. You do need to get the timing dialed in before you worry about carb adjustments. If it's mainly a street driven car I'd suggest running the vacuum advance. It'll help the plugs run cleaner as well as help with fuel mileage and have peppier off idle response.

TB is right about the wideband O2 sensor. I love mine. You can dial in every circuit for optimum performance
 
fishy68 said:
TB is right about the wideband O2 sensor. I love mine. You can dial in every circuit for optimum performance
Click to expand...

With oxygenated fuels, I believe that reading the plugs is nearly meaningless for all-around driving unless it's waaaay too rich or lean. Drag racers can usually read theirs, but that takes practice and a lot of knowledge.

With the wideband, you know you're in the ballpark. I got one last year and it's just a great tool to have.
 
Yeah, it's a 6210 model.
Thanks, for the help everyone. I'll play with the timing today and see what happens.

I know right now the car scares the crap outta my wife when I hammer it, lol. I'd like a little more though :)
 
Ok so I jetted this thing back to stock jets 60/83 and now it seems to stumble a little bit and hestitate in different spots between 1000-3000 rpm. Also it smells like its running WAY rich which it didn't with the larger jets in it. Weird I know, lol. Its also suckin gas like crazy with the smaller jets. Gonna go middle ground with the jets and see what it does.
 
Get your timing first, then dont worry about it unless your having trouble.
 
A lot of people equate a funny smell with running rich when in fact running lean can cause it to stink. Another common mistake is jets do not affect the idle mixture so if jetting is off it does not affect the way it idles or smells at idle. Have you worked out the timing yet? If not you might as well go hunting with a blind fold on
 
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