1981 Camaro Z28 350 SBC Engine issues.

Discussion in 'Troubleshooting & Diagnosis' started by HB_81Z28_80870, Aug 1, 2020.

  1. HB_81Z28_80870

    HB_81Z28_80870 New Member

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    Need some help with my engine as I had it rebuilt last year and since then have pulled it 2 times more with it presently at the engine builders. My issue is that I am puffing oil and burning it with oil leaks that I have found and corrected. I am running Kendall GT comp oil 20W50 with ZDDP in it for my flat tappet cam. My engine is a mild build, 30 over, mild comp cam 12-234-2 212*-218* @.050, roller rockers, Edelbrock EPS intake & Edelbrock 1406 600CFM.
    The engine runs strong with 170 PSI compression on all 8 cylinders. Timing on stock HEI was 12 static, 13 VA & 21 Mech.
    The engine when it was running had a coolant temp of 160-170* as I have a 2 core rad with rebuilt original water pump & 195* T-stat.
    Was wondering if the oil I'm using is too thick as it looks to me from the valves & pistons that there is a ton of deposit of hard carbon and tan discoloration on top of the pistons, with the valves having a sticky black deposit on the top of the valve.
    The engine builders are saying that is waaaaay too much fuel, go figure.
    Have uploaded photo's for a better idea of what's going on.
    Not happy about the multiple pulling of the motor, would like this to be the final time as I would just like to drive it.
    Thanks in advance for any comments or advice as I've been following this site for some time and have found the advice here is #1 with lot's of knowledgeable people.
     

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  2. Robert stuart Bell

    Robert stuart Bell Rsb78LT

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    That's rough, I know the frustrations of just wanting to drive but the car doesn't seem to want to.

    Not sure who built your engine or what they did but kinda looks like you got screwed or they gave you the wrong block back,
    The pics you posted is what my original 305 looked like after 280,000kms with leaking valve seals and I'm not sure how you'd over fuel anything with a 1406 unless it's broken like most of them.

    Unless your racing or live a 90°+ area 20-50w is a little excessive but not crazy, it gets to 105° at the very most here and I run 15-40w with no problems.
     
  3. berg2695

    berg2695 Veteran Member

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    Oil coming through the pcv system maybe?
     
  4. cadillac_al

    cadillac_al Veteran Member

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    I don't think the engine is getting warmed up enough. I don't know if that would really cause that much carbon though. I have never had anything that ran cooler than 195-200.
     
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  5. Camaro Tim01

    Camaro Tim01 Veteran Member

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    The engine when it was running had a coolant temp of 160-170* as I have a 2 core rad with rebuilt original water pump & 195* T-stat.

    ... How are you running at 160-170 if your thermostat is 195 ??, they usually run at or slightly above the thermostat temp... if youre running lower than optimum operating range and too cool, that could do it...

    looks like what they said, its way too much fuel, low octane fuel, or fuel with some additive in it thats leaving those deposits

    what gas are you running in there with 170 compression ??... thats about 11:1 ratio... you might need an octane booster additive or run a high octane to run/burn properly.... time to run airplane fuel
     
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  6. rchydzik

    rchydzik Veteran Member Lifetime Gold Member

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    I would look at oil coming down the valve guides. Assuming the guides are in good condition, look at the valve seals. Too much fuel should wash the valves, and there are deposits on the valves.
     
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  7. HB_81Z28_80870

    HB_81Z28_80870 New Member

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    Thanks guys for all your replies.
    Answer to your questions -
    Berg - I checked the PCV system by removing the valve cover air breather & plugging it, then I removed the PCV valve & put my finger over the hole.
    There was no vacuum which to me would indicate it's not sucking oil through the intake. Found that on a Blog from an old mechanic trick!!
    Camaro Tim - Tim I may have mislead you, I meant 170 PSI compression test. My motor is 9:1 CR, I have flat top pistons & 882 heads(75cc). Nothing too wild & it runs on 87 pump gas.
    I believe you might be on to something with too cool. My gauge on my estimation is around 160 to 170 as it is barely above the 1st line above the 100 mark at the bottom of the scale.
    The car will warm up & I use a thermo gun on the water neck & it is around 160*. I also checked the lower rad hose & it's 168*.
    The upper rad hose is not fully open as I can squeeze it & pinch it off. I have seen it up around 195* when I'm driving it at 3500 rpm on the hiway.
    rchydzik - I thought the same thing, but when I had the motor rebuilt the heads were completely redone & tested & when they pulled the heads the valve seals looked good.
    That's still the $1,000,000.00 question.
    Robert - I did receive the same block as it is a numbers match block.
    I am of the same thought that with the temp of the motor & thickness of the oil that maybe the secret to the deposits on the valves & piston tops.

    Stay tuned Gentlemen for the results. I will post the solution once I find out what's going on.
     
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  8. rchydzik

    rchydzik Veteran Member Lifetime Gold Member

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    That first mark is more like 185, right where you should be with that thermostat. The sensor has very high resistance as it comes up to temparture, and becomes much more linear as the engine approaches operating temperature.
     
  9. COPO

    COPO Veteran Member Lifetime Gold Member

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    If you had thinner viscosity oil then you’d have those deposits on the tops of the pistons and valves cause it would be thin like water. Try a hotter spark plug. AC R45 or R45S, NGK XR4-5 (4 is hotter), Autolite 86.
     
    Last edited: Aug 2, 2020
  10. Robert stuart Bell

    Robert stuart Bell Rsb78LT

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    Still running the stock hei?
    If everything is good with the valves, right shaft diameter, valve seats and seals are good and the heads aren't cracked I'd go with hotter plugs and think about getting an ignition box, msd's multi spark did wonders for my small block stinking like a rich pig
     
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