1. charlesvolare

    charlesvolare Well-Known Member

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    I have a fresh 360, 11:1 compression, mild roller cam, magnum heads. kb107's with rings gapped to 0.032". I have about 500 miles on it so far, but driving it every day.

    I took it out last Saturday to an autocross event and ran a few laps. One of my buddies noticed it smoked a little at idle. The next day, Sunday, I pulled the plugs and ran a compression test. 190-195 on most cylinders, #5 was a little lower than the rest but not anything crazy enough for me to remember (I can go find where I wrote it down if I need to). Sparkplugs all looked good, no fouling.

    It's only smoking at idle, warm, only under vacuum, and it is oil smoke. Starting cold, nothing. Driving around, nothing. I'm guessing pcv, but is there anything else I should look for? Valve seals would cause more smoking range I'd imagine. I'm still driving it, if it's bad enough to foul plugs I figured I can narrow it down to a single cylinder if it's something more.

    I'm thinking about plugging the valve covers and putting a vacuum gauge on the dipstick to see if the excessive crankcase pressure or vacuum.
    IMG_20200202_165743.jpg

    Autocrossing may or may not have caused it, that's just when I first noticed.
     
  2. volare 77

    volare 77 Well-Known Member

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    I had a issue years ago when I was just a youngster with a leak at the intake gasket.
     
  3. Aspen500

    Aspen500 Well-Known Member

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    It could be the intake gasket sucking oil from the valley into the underside of the intake ports. A big offender of oil smoke at idle (and on decel) is the valve guides and seals. They will only give the blue fog at idle or on decel with engine braking. Usually, the longer it idles, the worse the smoke gets. The fact that the plugs look perfectly fine leads me to the guides. Those are the 2 most common causes of what you describe. Oil rings would cause smoke on accel (probably not at idle unless really bad) and, the top rings would cause excessive crankcase pressure and can cause oil to blow out the dipstick or crankcase vent (or even seals), plus you should see evidence on the plugs. Guides generally only get oil sucked past the valve stems with high vacuum, such as idle or closed throttle decel.

    Just an FYI. Years ago I had an '81 D150 with a 318. it burned a quart of oil every 300 miles and had BAD blue smoke at idle and on decel, but not on accel or steady speed. I had an extra set of heads and had them overhauled with new guides, seals and valves. After bolting them on, no smoke and oil still on full mark at 3,000 miles before oil changes. From a quart every 300 miles to not a drop in 3,000, all from worn valve guides.
     
  4. charlesvolare

    charlesvolare Well-Known Member

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    Unplugging the pcv didn't change it. Capping everything and vacuum gauge on dipstick showed crankcase was building pressure, so I'd start to rule out intake gasket from that.

    When it's not 30 degrees and rainy I'll pull the valve covers and see if the valve seals are all looking okay, seals were fresh on the heads less than 20,000 miles ago.
     
  5. Aspen500

    Aspen500 Well-Known Member

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    If the guides are worn, even with good seals you can still suck oil in, especially with umbrella seals. Not saying that's absolutely what's wrong, just a good possibility.
     
  6. charlesvolare

    charlesvolare Well-Known Member

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    Couldn't wait, broke out the propane heater. Seals are all good and in place. Spark plugs are a whole different story. The picture in the first post is what they looked like 5 days ago, with about 450 miles on them. This is what they look like now, barely 30 miles more, if that:
    IMG_20200206_183508.jpg IMG_20200206_184629.jpg
    Definitely an issue with #6.


    Here's a video of the autocross on Saturday, and a around the 0:45 mark I'm hitting the rev limiter. Could that actually be high rpm detonation? My tach isn't working so I'm not 100% sure what the rpms were looking like and whether or not it was actually hitting the limiter. But then again, if it blew the head gasket into the lifter valley it would be sucking oil in on every decel and not really as much at idle I'd imagine.
     
  7. AJ/FormS

    AJ/FormS Well-Known Member

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    Are you running Cast Iron heads on that?
    On pumpgas?
    At what elevation?
    With what head gaskets?

    I don't know what I'm hearing in the vid, but it doesn't sound like a rev-limiter, and it don't sound good.

    As to the smoking, if you filled the mufflers with oil like I once did, it takes quite a few miles to burn it all out.

    2,8,3, and 5, don't look all that happy either. Are some of those on the same runners of a dual plane?
     
    Last edited: Feb 7, 2020
  8. charlesvolare

    charlesvolare Well-Known Member

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    Yep, cast iron magnum heads. 93 octane pump gas. About 330' elevation. Felpro 1008 head gaskets.

    Pulled the intake today, this was #6 runner: IMG_20200208_180610.jpg
    A few others seemed to have oily runners as well. Looks like I could've tightened the intake a little and it would've fixed it. I'm hoping that was it.
     
  9. volare 77

    volare 77 Well-Known Member

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    The problem with my intake way back then was the heads were cut too much to up the compression and the intake was off because the intake side was not cut along with it. After replacing the gasket about 3 times I finally realized what was going on.
     
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  10. Aspen500

    Aspen500 Well-Known Member

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    I was thinking the same thing. If your heads were cut, the mating surfaces will be out of alignment unless the manifold mating surface was cut to compensate. If not cut (either head or block deck surface), maybe only needed a retorque. I've noticed manifolds with vertical bolts (like a Magnum) will need retorqued after the manifold and gaskets "settle in". Usually takes 3 or 4 rounds before the bolts hold torque on initial installation, as it settles in.

    Hope you've found the cause of the oil!
     
  11. AJ/FormS

    AJ/FormS Well-Known Member

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    img_20200208_180610-jpg.jpg

    By the compression pattern, it looks like the angles are off alrightee,
     
  12. AJ/FormS

    AJ/FormS Well-Known Member

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    Wow! You and YellowRose from FABO, are the only guys I have heard of that can get away with that kind of pressure in a cast-iron chamber on pump gas.
    Kudus to you, for figuring out how to do it..
     
  13. BudW

    BudW Moderator Staff Member

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    Are you using a normal single or dual plane 4-bbl intake or the Magnum beer keg style intake?
    Intake Magnum.jpg
    The reason I ask is the lower gasket on the beer keg intake is known to suck oil out of the valley, more so than the cylinder head to intake gaskets do (but both gaskets can do so).

    My second question is which valve covers are you using? Most stock valve covers have a metal baffle to prevent rocker arm oil spatter from getting close to the PCV. Most aftermarket valve covers do not have (typically) a baffle and any oil splatter from rocker arms in vicinity of PVC valve will get sucked into that valve.
    This is an example for a chrome big block cover:
    iuWYHQE58S.jpg

    The only other sources of oil usage will be:
    - Piston rings (and/or pistons)
    - Valve guides and/or valve seals.
    - Oil not able to drain back into oil pan fast enough.
    - Intake machining (or lack thereof) to match cylinder head(s).

    If a somewhat recent rebuild – I don’t see valve seals being an issue (unless someone forgot to install 'em).
    Oil drainage is also typically not an issue on a recent rebuild (think sludge preventing oil draining).
    Excessive valve guide clearance and/or piston rings are both possible – but I suspect intake gasket might be more likely.
    BudW
     
  14. Aspen500

    Aspen500 Well-Known Member

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    My Dakota (3.9 Magnum) had the intake plate problem years ago at around 60,000 miles. Didn't notice excessive oil consumption really (1/2-3/4 qt per 3,000) but the idle was funky, like an air leak. I put the TSB update kit on with the new plate, gasket, longer bolts, etc. I seem to remember different manifold to head gaskets and bolts too were a part of the TSB. It was almost 20 years ago now, so I could be wrong about that part. Now at 172,000 miles and it uses MAYBE a cup of oil per 3,000 miles still. It took care of the idle problem as well. About half the plate gasket was sucked in and a couple inch long piece was completely missing.