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w3wilkes

Regulator / Gauge - Do I Need It?

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On ‎11‎/‎23‎/‎2017 at 12:20 AM, Stanley said:

I think 5 to 6 psi would be OK if you're running a return line.

Yes, I run the return line. I noticed when I replaced all the rubber fuel lines that the exit of the fuel rail on the motor is restricted which I'm guessing is to give some back pressure in the system.

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Good idea to set up lines from float bowl vents to clear plastic catch cans to make sure there's no overflow. The catch cans should be located where fuel will go on the ground if they overflow instead of pooling somewhere (like stock air cleaner) or going on the exhaust pipe.

I had the floats set slightly higher than stock for a while. Got about 1/2 ounce total overflow over a year.

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With the new airtex 8012s pump the psi raised to 4psi and nl overflow. Response got better but at 2.70 turns clockwise at the fuel mixture knobs of both su roundtop carbs. I even took a picture of the plugs for your opinion. Am i still too lean?20171128_130539.jpg20171128_125832.jpg

20171125_103035.jpg

20171125_103012.jpg

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Yes i know but if i go too rich i would then have a problem when the car is as idle as the plugs start the foul getting sooty black which causes the car to hesitate under traffic situations with a tendency to stall. I am using a cheap automatic transmission fluid for my su carbs. My problem is always at idle.

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 Go to 2.75 and check the plugs again after a few days. Small incremental changes. Try to keep the drive the same between plug checks. In other words, if the plug readings have been with, say, 1/4 traffic and 3/4 highway miles, try to keep the percentages the same. Don't read the plugs after idling in traffic one time and after highway miles the next. Try heavier wt. oil in the carbs and see if it helps throttle response. Heavier oil shouldn't affect the idle.

Edited by Mark Maras

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 You don't avoid it, it's part of the tuning process. I would suggest that while you're idling in traffic, keep the RPM's up at a happy idle, maybe around 1500 RPM's or a little more. Or, if the engine starts easily when warm, shut it off when you have to sit and idle. See if that will keep the plugs from fouling. The needles, springs, float level, could cause the sooty plugs at idle. I think you had SM needles, what color springs are you running? I know you set the floats but you wouldn't be the first person to have to go back in and tweak them a bit. I won't be convinced that they're right until you pull the domes and pistons and tell me what the fuel height in the jet is at 2 1/2 turns down.

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@jalexquijano Sitting here thinking back to what I believe was the original problem, which was the plugs loading up and getting sooty at idle, I visited the "WayBack Machine" and remembered something from long ago that I ran into. Another possibility that would cause that condition is a barely leaking needle(s) and seats and or excessive fuel pressure. Theoretically, a less than perfect (but not belching fuel terrible) seal can allow excess fuel to bypass the needle and seat and raise the float level at idle when the engine is using the least fuel, causing a rich mixture. The longer it idles the higher the fuel rises in the float chamber. As the engine rpm's and load increase the excess fuel in the float chamber is used and the fuel level returns to normal. Did you ever notice plugs 1, 2, and 3 being lighter or darker than 4, 5 or 6? A possible sign of one carb leaking. Kind of a shot in the dark but your symptoms seem to relate to this. It 's not that uncommon in carbs. Thoughts? 

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7 hours ago, Mark Maras said:

 I visited the "WayBack Machine" 

“And now, here's something we hope you'll really like..."

Talk about a flashback!

  • Like 1

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 Still looks too lean. The white porcelain should be a tan color. Does it still run rich at idle and load up (turn them black) the plugs? I'm assuming the pictured plug had little idling time. Please confirm.

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Yes it just had a little of idling time at the garage and short traffic lights. I read in another forum that i could have a vacuum leak somewhere and that it be causing the plugs to foul sooty black at idle. Do you concur?

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1 hour ago, jalexquijano said:

Yes it just had a little of idling time at the garage and short traffic lights. I read in another forum that i could have a vacuum leak somewhere and that it be causing the plugs to foul sooty black at idle. Do you concur?

  A vacuum leak would add more air to the mixture. The normal symptom of a vacuum leak is a higher RPM at idle. Remember, anytime you suspect a lean condition, you can ease the choke on and see if performance improves.

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