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I tweaked my timing and carb fuel/air settings today, with some success. At first I had increased timing too much and the thing was trying to cut out when driving 20 mph or so. The idle seems better (though still a little rough), and power may be a tad better as well. Time will tell if my gas mileage improves. Anyway, I noticed last week that if I am going 80+ mph on the freeway and let off the gas I begin blowing smoke out the exhaust. It only happens when I have been going very fast and then slow down. When I got off the freeway it appeared as though smoke was coming from underneath the car. I assumed it was because the wind was blowing the exhaust that way etc. Well, this morning I crawl under the car to adjust the kickdown linkage, and I notice an oily substance all over the rear part of the tranny. Specifically, the transmission mount and surrounding area. It looks more like oil than tranny fluid. I noticed that some of the substance had gotten on the exhaust pipes and burned away. That wasn't there last weekend when I was under there. I didn't think any more about it until I was cruising down the freeway this afternoon and started blowing smoke. Is it possible that I'm blowing oil out when I turn that many RPMs? Something is definately going on, but I don't know what. The smoke starts when I slow down, and goes away after a couple of minutes (even faster if I get off the freeway and slow down significantly). Any thoughts?

'65 289 4V Edelbrock 1405 600CFM C-4 yada yada yada
 

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Gone but never forgetten
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The first 2 thoughts that come to mind if it's oil and not tranny fluid is a small leak in a valve cover gasket, or even more likely, a leak at the back of the intake gasket. If you're intake is leaking, it will run down the bellhousing and "coat the top of the tranny. As you get going faster the oil may tend to leak more, but most it starts blowing all over the place and onto hot exhaust pipes. A small amount of burning oil on an exhaust pipe wouldn't be very noticeble to you in the car, but would become much more obvious right after slowing down.

At that point, the oil isn't "splashing and blowing" as hard, no longer is getting on to the exhaust, and stops smoking. How's that sound?

Just a wild guess, but it could happen /forums/images/icons/smile.gif

If you always do what you've always done,
You'll always get what you've always got

http://www.classic-mustang.net/johnpro
 

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Higher speed=more rpm=more blowby=pressure follows path of least resistance...

Check your valve cover gaskets and the back of the intake manifold.....and the PCV grommet...

You may be surprised by the hurricane going on in there at 80mph...things end up in places you wouldn't believe..*G*

Pat
http://www.jps.net/binay/webdocs/strtmstng002_sml.JPG
 

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Could be coming from several places that you don't see by just looking at the top of the engine. Valve covers, rear intake. My small oil leak is "probably" coming from not putting a little sealer on my bolts for the flywheel to crankshaft. My transmission stays a little damp. And like you the oil gets on the exhaust. The faster you go, the harder the wind blows & pushes the oil onto the exhaust.

66 Coupe, 302, Auto, 3.25 gears. Candyapple Red with White Pearl Stripes. Cragars.
 

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1966 coupe and 1970 sportsroof
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