new 383 smoking a bit...hmmm... - Team Camaro Tech
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post #1 of 13 (permalink) Old Feb 24th, 03, 10:25 AM Thread Starter
 
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Help! I'm Getting a little blue/black smoke that gets worse when engine gets warm, smoke is very acrid (strong smell/burns eyes) so I'm 90% sure it's fuel. Engine is a 383 stroker w/TFS aluminum heads, CR is 9.8:1, cam is a crane 119831 full hyd roller (284/292) with 1.6 roller rockers on intake and exhaust. Tank is full of 91 octane. Timing is set to 9 degrees initial, distributor is a new proform generic HEI unit. Engine is running real nice and strong, it idles exceptionally smooth for this size of cam. Carb is an edelbrock 750 on a performer RPM intake, carb is adjusted for best lean idle, the screws are only about 3/4 of a turn out from their seats. Fuel pressure regulated at 6 psi. One buddy thinks it's simply spewing unburned fuel due to the cam's overlap...Smoking seems worse at idle than at higher RPMs, but it is still there through the RPM range, and it puffs some under hard accelleration...Oil shows no signs of contamination. Does not seem to be coolant related, from what I can tell..no white smoke. Temps never exceed about 170. Any ideas? Could it be that the Edelbrock carb (unmodified, right out of the box) is set up too rich? Maybe a hotter plug is needed? (I'm running a set of Autolites as recommended by Trick Flow, will have to check the plug# when I get home tonight..)
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post #2 of 13 (permalink) Old Feb 24th, 03, 02:44 PM
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Are your plugs getting fouled? My 355 with a healthy cam seemed to idle well. But it always fouled the plugs and ran rich. I discovered that I had the primaries opened to far and fuel was being pulled in through the transfer slot. On Holley's there is a stop screw on the bottom side of the bottom plate that you can use to crack open the secondaries so that you can close the primaries and get back into the idle circuit. Some people will drill a small hole in the primary butterflies to allow them to close the primaries and get back into the idle circuit.
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post #3 of 13 (permalink) Old Feb 24th, 03, 06:00 PM
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Too much fuel or an air restriction on the intake making it rich. Make sure it can BREATH BABY BREATH. If it still does it with the filter off it's mixture. Nice engine. Summit has a performance section you can read for fix's.
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post #4 of 13 (permalink) Old Feb 25th, 03, 06:22 AM Thread Starter
 
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Thanks for the advice, snatchin'...I'm going to pull the air cleaner off and take it for a drive to see what happens..I probably won't get a chance until this weekend. The air cleaner that is on there is kinda old...havent yet decided what I want on there yet.

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post #5 of 13 (permalink) Old Feb 25th, 03, 10:00 AM Thread Starter
 
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GlennC, I'm running an Edelbrock carb, 750CFM, VacSec, electric choke. No adjustments, new, straight out of the box. I have heard that these carbs are sensitive to excessive fuel pressure. I'm running a steady 6psi. (Edelbrock manual recommends 6-7) Another post somewhere said that even 6psi may be too much. I'm going to knock it down to 4-5 and see if that changes anything. I really want to make sure I've eliminated all other possibilities before tearing into the carb...
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post #6 of 13 (permalink) Old Feb 25th, 03, 10:40 AM
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Quote:
Originally posted by Snatchin'gears:
Too much fuel or an air restriction on the intake making it rich. If it still does it with the filter off it's mixture.
If I'm not mistaken, while a restrictive air cleaner will harm performance, it won't affect mixture. The reason is that the bowls and air bleeds are referenced to the same pressure inside the air cleaner. A choke on the other hand restricts flow to the primary throttle bores, but the bowls and bleeds are referenced to the area above the choke plate.

I wouldn't recommend running the engine on the street without an air cleaner. Suck a leaf in and you'll be fighting another problem and still have a mixture issue to fix.
-dnult
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post #7 of 13 (permalink) Old Feb 26th, 03, 10:40 PM
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No matter what it's too rich and besides too much fuel there is too little of air that makes the too rich of a mixture. I'm not sure about 383's and 6 lbs of preasure but I'd figure thats ok especially if he wants what the 750 can put out. Ho hum.
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post #8 of 13 (permalink) Old Feb 27th, 03, 10:45 AM Thread Starter
 
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So does anyone out there have edelbrock tuning experience with a performer 750CFM carb on a 383? It seems like it's definately the carb setup, rather than some sort of obvious problem...
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post #9 of 13 (permalink) Old Feb 27th, 03, 04:06 PM
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there's a good article on page 87 of the current Camaro Performers on tuning an edelbrock
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post #10 of 13 (permalink) Old Feb 27th, 03, 05:53 PM Thread Starter
 
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Hey thanks DjD! I picked up that issue the other day and hadn't had a chance to read it. That article by Ron Ceridono seems very helpful. I ordered an edelbrock cal. kit from Summit and I'm going to work on the tune this weekend. Thanks!!
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post #11 of 13 (permalink) Old Mar 4th, 03, 06:28 AM
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I've heard that edelbrock carbs ususually run on the rich side. You can change that with some jets and rods. The owner's manual or edelbrocks website should have the procedure to do this.

Another thing, with a new engine, the rings may not be seated fully yet, and the smoke may go away with time. If the smoke is from oil.

Good luck.

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post #12 of 13 (permalink) Old Mar 4th, 03, 09:57 PM
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Since there appears to be a predominance of carbs shipped out of tune for what they are applied to I think california should require all carbs sent there to include a months supply of a nitro fuel additive to help prevent air pollution.
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post #13 of 13 (permalink) Old Mar 7th, 03, 01:16 AM
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rwhite692,

I recently ran into a simular issue with a friend that has an Edlebrock on his Chevelle. He was always concerned with a small puff of smoke and excessive reak of fuel. I loaned him my regulator assembly w/fuel gage and sure enough his fuel pump was overpowering the carb. He has since bought his own regulator setup and has put this issue to rest. I'd check this and refer to the users manual for the right jetting and rod combo

Best of luck,
Tom
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