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Author Topic:   Reading an alcohol plug
10car
Dirt Roller

Total posts: 14
posted April 30, 2002 10:15 PM
Since alcohol burns cleaner can you read a plug the same. The carb was used when I got it with 70 and 71 jets, seemed small so I checked carb it is a alcohol carb. I took it out on practice day and it ran good. I went ahead and jetted it to 74 and 75 and ran it in he last session and it burped all over the place. So for the first race I took down to 71 and 72 it ran better but still burped so I took it back to 70 and 71 for the next week and it seems to run fine. Maybe someone has done some internal work on it I don't know. The porcelin seems pretty clean but there is some browning on the metal. I pulled them after 3 nights and looked under a mag. glass w/light and didn't see any traces of metal. I have never ran alky before. any suggestions. Thanks

Gene
Dirt Maniac

Total posts: 183
posted May 01, 2002 04:42 AM
2 common ways to check are 1) exhaust temp, you need a 300 dollar gauge but its the best method. 2)As long as yor buddies can see a little blue flame out the exhaust your still a tad rich. This method is free and all the kids in the grandstands will cheer for ya.

George Gilliland
Dirt Full Roller

Total posts: 39
posted May 01, 2002 08:52 AM
With Methanol I find that the plugs only come into the picture when you are extreme on the jetting or timing. Take off the headers and look. The headers and ports should be charcoal grey and the exhaust valves should be 1/2 dark and 1/2 white on each valve. The temperature is also an indicator of the extemes.

dirtracer14
Dirt Freak

Total posts: 333
posted May 01, 2002 11:28 AM UIN: 23443678
So if i blow that cool blue flame when i lift than im a tad rich? I tried a new carb this weekend that had really big jets 181 it didnt seem right packing the track so we put the old one on 157. The old one has allways put a flame out when i lift, do i need to drop down a few?

Gene
Dirt Maniac

Total posts: 183
posted May 01, 2002 05:47 PM
Blue is a little rich, orange is too lean, also a sharp crackling sound when you back off of it from the exhaust tells you its lean. Running a little rich on alky will not hurt the power much, and its a lot safer.

dirtracer14
Dirt Freak

Total posts: 333
posted May 01, 2002 06:20 PM UIN: 23443678
I have allways had the blue flame...well most of the time. Its not milking the oil so i figured i was ok, nor did i get a blubber so i just stay close to where i am at now. I called BG today to get some info on the new carb (not to friendly)and he gave me the #s that it left the shop with now i just need to get some jets and im ready to put it back on.

10car
Dirt Roller

Total posts: 14
posted May 01, 2002 11:17 PM
Thanks for your help I know I blow a blue flame cause my wife tells me my 6yr old daughter wants to know why daddys car is on fire. ha haha more help or suggestions is always welcome. I got a holley pro series carb today that has only been on a dyno a couple times I might try it sometime. I hate to mess with stuff when it is running good.

spde
Dirt Full Roller

Total posts: 63
posted May 01, 2002 11:17 PM
I run a good plug to begin with, an Autolight Platium or NGK platiums. I know that plugs will still show color on the porcelan deep into the plug. I try to to get a nice light tan. The other thing is to measure your exhaust temps!!! This is a must on alcohol. We check our temps 1" off the heads and in the middle of the exhaust tubes. I run about 950 dergrees at an idle and 1250 degrees at 3,000 rpm. I'm not a 100% sure but I think alum. melts around 1700 degrees so we try to keep under that. Also water temp plays a big factor in the motor. If it is to cold (under 180) the car will run rough. We use just the standard restricters, no therosates!! Anyways I got this temp gauge at Sears. It works from a digital meter, the hole set up cost me about $75. This also comes handy to measure tire temps. I have a freind that has a temp guage you can leave on the car and while your running it will record the data for you to look at. This will record from 2 seperate header ports. I think it costs $200-300 I'm not sure on this. He says it works well and is fast updating. Anyone interrested I can get the price and info for ya . ltr hope this helps Spde aka
Dirt Racing Motorsports

George Gilliland
Dirt Full Roller

Total posts: 39
posted May 02, 2002 12:14 PM
Aluminum melts at about 1000 deg. F.

ryan
Dirt Freak

Total posts: 277
posted May 06, 2002 10:52 AM
1220 to be exact

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