Last post on Sep 14, 2007 at 4:23 PM
You are in the Speed Shop Tuning and Modification
What is this discussion about?
Chevrolet S-10, Performance Mods
#7 of 26 Re: BLACK OIL [okko1]
Sep 03, 2007 (3:16 am)
Carb is Edelbrock 1406 600 cfm electric choke. air cleaner is large 13-14" x 3 round no brand name. engine is about 3 years old since rebuild with 20 k miles engine doesn't use oil
thanks for the reply
#8 of 26 Re: BLACK OIL [drcarp]
Sep 03, 2007 (6:38 am)
thats a very good carb. is this an egr motor
#9 of 26 Re: BLACK OIL [okko1]
Sep 03, 2007 (11:44 am)
No erg no smog no converter
headers and dual exhaust
thanks for the reply
#10 of 26 Re: BLACK OIL [drcarp]
Sep 03, 2007 (1:54 pm)
From the sound of things I wouldn't touch a thing. It seems your got it right where you want it.
#11 of 26 Re: BLACK OIL [hoodlatch]
by Mr_Shiftright HOST
Sep 03, 2007 (5:55 pm)
The only explanations I can think of for "black oil" is compression blow-by into the crankcase, fuel contamination of the oil from over-rich mixture, (and that gas in the oil doesn't burn off in a 16 mile trip), OR the air filter is letting in way too much dirt because it's not sealing right.
You should check to see if your oil dipstick reads HIGHER after your short trip (wait 15 minutes after you stop).
Excess fuel in your crankcase may be acting like a solvent all throughout your engine (this is not a good thing and must be corrected immediately).
I'd suggest you treat your symptoms of black oil with the utmost seriousness until you track it down.
Oil analysis might tell the story.
#12 of 26 Re: BLACK OIL [Mr_Shiftright]
Sep 03, 2007 (6:09 pm)
THANKS FOR THE REPLY
WILL CHECK CARB MIXTURE SETTINGS AND TIMING TOMORROW.
#13 of 26 Re: BLACK OIL [drcarp]
Sep 03, 2007 (6:35 pm)
that carb your useing is pretty simple to change jets and metering rods in. there is kit for around 60.00 i think. be careful if the engine has a larger than stock cam that you don't get to lean. that carb with factory jets in good working order should be 90% efficient on any small block.
are you getting any oil thru your pvc system or in the breather it's self
#14 of 26 Re: BLACK OIL [okko1]
Sep 04, 2007 (1:35 pm)
IT DOESN'T LOOK LIKE ANY OIL AROUND PVC AND THE BREATHER IS TIGHT AND CLEAN. I LEANED OUT THE CARB TODAY LET'S SEE IF THIS IS THE PROBLEM.THANKS FOR THE INFO
#15 of 26 Re: BLACK OIL [drcarp]
Sep 09, 2007 (11:45 pm)
Your gas mileage of only 8 mpg, along with black oil, tells me that the carb is way, way too rich. This amount of richness cannot be cleared up by just adjusting the idle mixture screws. It is either coming from 1> a float level that is set too high, or a float valve that doesn't shut off the fuel when the fuel reaches the correct level, or a float that is heavier than it should be (plastic float that has become porous and soaked up gasoline or a brass float that has a leak in it). 2> A choke plate that doesn't open fully when the engine warms up, or a choke pull off (also called choke vacuum break) that either has a ruptured diaphragm or is not getting any vacuum, or a choke pull off that is improperly adjusted, and doesn't pull the choke open far enough. or 3> clogged idle air bleeds or clogged main air bleeds, or air bleeds that are too small for this engine, or stuck metering rods, wrong size metering rods, or main jets that are way too large for this engine.
Another thing to consider is that the distributor vacuum and centrifugal advance mechanisms must both be working properly, before the carb can be set. And the ignition system must be producing a spark of adequate intensity, while the spark plugs must not be misfiring or carbon fouled.
But, in any case, the choke plate should open fully when the engine is warm, and if you look down into the carb air horn right after shutting off the engine, there should be no fuel spilling into the engine after it is shut off.
If you have changed the compression ratio or the cam, then whatever jets came in the carb may be totally off for what the engine now needs. If your carb was not intended for the type of engine it is on, it may also be too rich for that reason. In those cases, you need to either get an exhaust gas analyzer and keep leaning out the jets and metering rods until the air fuel ratio reaches about 12-1 under heavy throttle, and about 14-1 to 15-1 under easy driving. Or take it to a performance shop that has a dynamometer, and have them blueprint the carb by running the truck on the dyno and monitoring the exhaust gas.
If you are good with carbs and tuning, you can also do this by driving the vehicle, and reading the appearance of the spark plugs. But carbs have many different circuits with overlapping effects; so it is necessary to understand how these circuits work, in order to know which parts to adjust and what to change.
I hope this information gets you on the track to fixing this problem. Let me know, if you have further questions.
#16 of 26 Re: BLACK OIL [zaken1]
Sep 10, 2007 (11:09 am)
wow thanks for the reply. i will follow up on these answers and let you know