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Author Topic:   Alky plug reading
chapa73
Dirt Maniac

Total posts: 171
posted October 28, 2005 02:45 PM  
Okay,No matter what I have changed on jets,my plugs always look like they are lean(From what Im used to seeing on gas)
I talked with a couple local guys and they have told me that reading plugs with alky is pretty tricky,So my question is without sending to a dyno,how do you guys tune a engine with alky?

Is there any CHEAP tools that you use?

Todd83C
Dirt Full Roller

Total posts: 54
posted October 28, 2005 04:33 PM  
I talked to a engine builder that gave me a good starting point and went up from there. My plugs had a slight brown tent to them after running a race. But remember better to a bit rich and foul a plug thene to be lean and burn a piston or somthing!!!!! Look for sings on the plug for running too hot, Thats the way i did it.

A. Bighurry
Dirt Full Roller

Total posts: 38
posted October 28, 2005 08:49 PM  
Plugs won't color as quickly with methanol as with gas. A good precaution is to buy a small magnifying glass with a light on it. It's made by several companies like Comp, etc. You can check your plugs closely and make sure that you have no metal transfer from pistons or valves onto the electrode. The little spots of metal would be caused by a lean condition. Start with a safe jetting and work down 2 sizes at a time, monitoring performance and plugs. Run hot laps and check them before it idles much.

rocket36
Dirt Freak

Total posts: 216
posted October 29, 2005 05:51 AM  
if you see little spots of aluminum on the spark plug, its too late, you've already detonated the cylinder way too much.
the magnifier is the way to go and read the colour slightly further down the plug but the a similar colour as on gas.
alky definitely takes longer to "colour" a plug but you really should do this during a practice session, as to get a true reading, you need to go from racing conditions & rpm to engine shut down as quick as possible with minimal run down time. by the time you finish a hot lap, do a cool down lap and then idle into the pit area, the plug reading will have changed (this is why a dyno is an advantage but not a nessesity).

A. Bighurry
Dirt Full Roller

Total posts: 38
posted October 29, 2005 08:12 PM  
In a perfect world we could all shut the engine down without idling and do a plug reading. If you can't, doing it after hot laps will have to do. Like I said, starting out with a SAFE jetting and sneaking up on optimal jetting by going down 2 sizes at a time and reading plugs works. You can tell by the performance if the engine likes the leaner jetting and by the plug COLOR and LACK of metal transfer that you are still safe. If you watch them closely you'll catch the metal transfer before tearing anything up. Years ago we went too far down on jetting and caught it by using the magnifying loop. We caught it in time and it didn't hurt the motor. Naturally you don't ever want to see it and if it's done right you won't. Lean is mean but hurts parts so watch the plugs closely.

A. Bighurry
Dirt Full Roller

Total posts: 38
posted October 29, 2005 08:14 PM  
I do agree on the practice session thing. That would be a perfect time to do it.

littleb24f
Dirt Full Roller

Total posts: 36
posted October 30, 2005 11:07 AM  
to properly check alky jetting is by a exhaust temp gauge. or wide band o2 sensor. reading the plug on alky is a waste of time. unless you dye the alky so you can see it on the plugs,which nobody does. I use my starting point set by my carb builder and go from there,most of the time it's dead on. my carb guy tells me to adjust by sound and water temp. if it flutters and sluggish, to rich, if it screams and water temp up, to lean. alky is forgiving if to rich and for the most part lean also. that's why it's hard to jet if you don't have a exhuast temp, or o2 sensor. we have access to a chassis dyno with a wide band o2 sensor so I can have everything set before the season starts. takes the quess work out. hope this helps.

[This message has been edited by littleb24f (edited October 30, 2005).]

A. Bighurry
Dirt Full Roller

Total posts: 38
posted October 30, 2005 08:31 PM  
Yes, an EGT sensor would work great. A dyno would be even better. I didn't mention it because the original post stated that he was looking for a cheap tool that would help him at the track. We don't have any trouble reading ours. I do know that if you're running too rich it can wash the plugs and you can't read them. We can also tell by the way the car runs and by engine temp, although we don't consider the carburetor part of the cooling system like a lot of the people we're around do.

Kromulous
Dirt Forum Champ
Total posts: 815
posted October 31, 2005 01:11 PM  
Alky is forgiving when rich, that is a good point.

Let me make a suggestion, we burnt 4 pistons this year, and spent over $400 dollars in head gaskets reapairing it each time, let along the pistons and rings. Our first year on alky.

Richen the motor up till it bluppers, and loads up, fouls plugs etc. Then lean it out from there, with small adjustments. You may milk up some oil, and other things, but its best to error on the rich side, because on the lean side you will be replacing parts.

Once you lean it out to where it runs good run it, it should be ok, it may still load up alittle idling.

As well remember with alcohol, the cooler it is out side, the more fuel you need. Cool needs fuel. So if you running a 94 jet all summer and then fall comes and it drops 20 degrees outside, you better be going bigger on the jets.

Anyway thats some things i learned this year running alky, it can be frustrating. Also get a Willy's carb if you can pick on up cheap, there awesome for tuning.

Krom.

goinrcn44h
Dirt Freak

Total posts: 206
posted November 02, 2005 07:32 AM  
Once you get a ballpark jetting, get a good density gauge and adjust from there. on my injection, I know where my barrel setting is closest week to week, I check that every so often. I recheck my low speed and hi speed weekly and clean them out and clean it all. as well as nozzles and blow the lines out. I had a pop or sputter for a while that was very elusive because I wasn't checking my density after the main. my hi speed was a touch soft and gettin too lean on top but wasnt too bad to bring water temp up. so now I have it set and rarely change it or my low speed. based on density I adjust my main pill and thats it really. I limit my at track as much as possible so I can focus on chassis. same with plugs and wires, spare cap and mag ready and setup to go. if anything is askew I just swap out and worry bout it later. but on methanol, maintenance is more important than being spot on. being lazy will whack out your jetting every week and you'll run in circles... trust me here......
44H

chapa73
Dirt Maniac

Total posts: 171
posted November 02, 2005 07:50 AM  
Thanks guys for all the reply's.
From what you guys say to look for,Im on the rich side,Car will load up at idle.Also when I come off the track I can smell the exuast really bad,and cant never start the car and run it for any amount of time in the garage.

goinrcn44h
Dirt Freak

Total posts: 206
posted November 02, 2005 10:57 AM  
With any jetting whether lean/rich/or spot on methanol is gonna burn the eyes somethin fierce.. first lesson w/ methanol... but yea, stay on the rich side.. an engine 10% lean will lose more power than one 10% rich and cost tremendously less in the long run. a piston will tend to melt faster when on methanol as well.. also when idling or rollin under a yellow its a good idea to slightly pinch off the fuel shut off, just dont forget to open it back up before ya firewall it or it will get real fast, real hot and real dead....lol..
44H

A. Bighurry
Dirt Full Roller

Total posts: 38
posted November 04, 2005 05:11 PM  
You can be rich at idle and still be lean on the track. The mixture screws in the metering blocks adjust your idle mixture. It might even be bleeding over out of the boosters. I wouldn't go jetting down to try to clean up the idle.

chapa73
Dirt Maniac

Total posts: 171
posted November 09, 2005 11:13 AM  
thanks guys!

16Again
Dirt Roller

Total posts: 17
posted November 11, 2005 08:44 PM  
There is a web site that has a very good articla written on reading spark plugs. Check out www.4secondsflat.com

nine finger
Dirt Forum Racer

Total posts: 85
posted November 21, 2005 12:15 PM  
pull your header and look in the port. if the top of the port is washed clean its rich.

wareagle87
Dirt Roller

Total posts: 10
posted November 22, 2005 07:30 AM  
Some of you guys talk about EGT. What is a good temp?

juliaferrell
Dirt Freak

Total posts: 375
posted November 22, 2005 09:48 AM  
The proper EGT is determined mainly by V/E and compression ratio......Ie....a 15:1 engine might like 1100 as a 9:1 engine may want 1400. Mainly determined on a dyno by getting peak torque at a specific rpm.

wfoondirt
Dirt Forum Champ
Total posts: 510
posted November 22, 2005 10:55 AM  
All good advice above but noone has mentioned the downside to running rich. A rich mixture will cause excessive cylinder wear which will result in having to bore the block and replace pistons. 90% of the mods I've been around are way too rich either because the don't know how to tune them or think they are better off to be way rich. I'm not triing to say that its better to run lean because its not, just triing to make people aware that being to rich can be just as costly in the long run.

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