Spark Plug Carbon Fouling |
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Spark Plug Carbon Fouling |
tornik550 |
Aug 5 2008, 12:03 PM
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#1
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Senior Member Group: Members Posts: 1,248 Joined: 29-January 07 From: Ohio Member No.: 7,486 Region Association: None |
I was hoping tha tyou guys could help me with a little problem. When I first purchased my 73- 914 a few years ago, I took out the spark plugs and they looked great. I started driving it myself and now I always have a huge amount of blakc carbon deposits even after only a few minutes of driving. I realize that black deposits normally suggest too rich of mixture however I have not made any changes to the carbs so I cannot figure why this would happen. The only thing that I changed was fuel. I also used 93 octane fuel, not sure what PO used. After this has happened, I have played with the mixture setting on the carbs however I wasn't able to fix the problem.
Could this be from a higher octane fuel? Timing problem? Too cool of plugs? Engine info- 1.8l case however 2.4l due to new cylinders/pistons... 2.0l heads msd 6al ignition bosch 050 dist with pertronix timing set at 27 degrees at 3000rpms plugs-autolite with 63 temp, also tried 64 temp, also tried bosch plugs but I dont remember the number 93 octane fuel plug gap .045 (due to msd ignition) I clearly do not have a good understanding of plug reading. I have read quite a bit however I cannot figure out an answer to my specific problem. Any ideas would be greatly appreciated. Thanks, Steve dual weber 40idfs |
904svo |
Aug 5 2008, 12:15 PM
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#2
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904SVO Group: Members Posts: 1,118 Joined: 17-November 05 From: Woodstock,Georgia Member No.: 5,146 |
What size ventures do you have, also what jets are you using?
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r_towle |
Aug 5 2008, 12:23 PM
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#3
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Custom Member Group: Members Posts: 24,584 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
Really...this is a carb issue.
Describe your intake setup. Carb (s) Main jets Idle jets Air correction jets Venturis. Also, camshaft and head flow numbers to be really accurate. It can be done without those numbers. What type of driving do you do with the motor?? Street, track, Autox?? A mix of all? Rich |
tornik550 |
Aug 5 2008, 12:39 PM
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#4
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Senior Member Group: Members Posts: 1,248 Joined: 29-January 07 From: Ohio Member No.: 7,486 Region Association: None |
I will get the settings and sizes when I get home tonight. I use th ecar for a little bit of everything- street, track...
I take it that the higher octane fuel would not be the issue? |
r_towle |
Aug 5 2008, 12:48 PM
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#5
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Custom Member Group: Members Posts: 24,584 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
not really an issue for running to rich...to much fuel is to much fuel.
Around town you are running on the idle circuit for quite a bit of driving. The size of the venturis, the size of the intake valve, and the jet sizes are all going to contribute to getting this to work. The idea is to speed up the intake charge to bring in MORE air... this require making the venturi/valve smaller, and possibly the idle jet smaller also.... gotta see what you have first. See if you have the build sheet for the heads and camshaft...it makes a difference. Rich |
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