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Thread: I really am idling with 40 degrees advance
          
   
   

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  1. #1
    pnut is offline CHR Member Visit my Photo Gallery
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    I really am idling with 40 degrees advance

     



    After thinking that my timing marks were off, I discovered using a piston stop that they were right on.

    My Small block chevy with mild cam and Qjet is running quite well. No pinging (that I can hear, but loud muffler), staying about 200 degrees with 180 tstat, and generally all seems ok. BUT at idle, the timing shows 40 degrees. When I rev the engine when sitting still to bring in all of the centrifugal weights, I get to 58 degrees, and it seems to be doing fine. I drove 50 miles last week this way (25 miles to and from work).

    I have an adjustable vacuum canister, including a limiter plate set at about 16 degrees max vacuum. It starts well too, even when hot (a bit tight, but not too bad).

    Should I be worried? When I reduce timing, the power goes down. When I get to 12 static, 26 (or so) with vac, and 38ish max with static, vacuum, and centrifugal idle, it spits pops and runs poorly. It acts like the timing marks are off, but I know they are not!

  2. #2
    Dave Severson is offline CHR Member/Contributor Visit my Photo Gallery
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    Are you certain the cam and crank are phased correctly?????
    Yesterday is history, tomorrow is a mystery, Live for Today!
    Carroll Shelby

    Learning must be difficult for those who already know it all!!!!

  3. #3
    nitrowarrior's Avatar
    nitrowarrior is offline CHR Member Visit my Photo Gallery
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    Dave, I'm with you on the cam part. Very suspicious.
    What if the "Hokey Pokey" is what it's really all about?

  4. #4
    R Pope is offline CHR Member Visit my Photo Gallery
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    Believe me, your engine is NOT idling with 40 degrees advance. You are timing it on the wrong cylinder, or something. It would kick back and blow the starter off before it ran like that.

  5. #5
    Frisco is offline CHR Member Visit my Photo Gallery
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    IF you have your idle RPM set above 800 and you are running FULL manifold vacuum to the vacuum advance , then you may be running 40 degrees advance at that idle. This would depend on how much mechanical advance and vacuum advance is being added to the initial at your idle RPM.

    The correct method to check/set the timing is to disconnect and plug the vacuum advance hose from the vacuum advance cannister. You should also have the trans (if automatic) in drive (be sure to set the emergency brake and block the wheels and do NOT rev the engine up when checking this way. Also would be a good idea to have someone with their foot applying the brakes.) and the idle should be in the 650-750 RPM range.

    Checking at a higher RPM will cause an incorrect reading as the centrifugal advance weights will have begun to open and will cause some additional timing.

    Checking with the vacuum advance hooked up will also cause an increase in the timing since their is no load on the engine the vacuum advance unit will also increase the timing.

    You are checking the timing incorrectly.

  6. #6
    pnut is offline CHR Member Visit my Photo Gallery
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    40 degrees is WITH vac advance. I'll post up each component tonight, but I think that's about 25 static. I was idling at about 700 when checked, so below where the centrifugal comes in. With centrifugal all in, it shows about 56-58 (all 3 full in).

    Attached is a picture of the timing chain alingment marks when I did the cam swap this winter (before I bent the locks over).

    Denny, you answered "absolutely". Do you mean I should absolutely be concerned?
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  7. #7
    pnut is offline CHR Member Visit my Photo Gallery
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    My timing (just measured) is:
    24 degrees static at 700rpm
    40 static + vacuum at 700rpm
    60-62 static + vacuum + centrifugal at 2800 rpm

    The cam is Lunati Voodoo 60101
    Advertised Duration IN/EX: 256/262
    Duration @ .050 IN/EX: 213/219
    Gross Valve Lift IN/EX: .454"/.468"
    LSA / ICL: 112/108
    Valve Lash IN/EX: Hyd/Hyd
    RPM Range: 1000-5500

    By the way, I was extremely careful to follow the break in to the letter. I'm learning alot, but now I know why people go and buy turn key crate motors. What the hell? It seems just fine, but the numbers just don't add up. I'm losing my motivation real fast with this damn motor.

    Now what?

  8. #8
    C9x's Avatar
    C9x
    C9x is offline CHR Member Visit my Photo Gallery
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    The engine idles ok at the higher advance rate because it takes a while for the lean idle mixture to burn.

    Do you have an amplified ignition box
    Something along the lines of an MSD6al?
    And are you using a dial-back timing light?
    Perhaps one of the Penske ones from Sears?

    I found when timing my 462" Buick engine (455 series engine) with a Penske dial-back it was off about 20 degrees.
    The original timing light - also a Penske - a non dial-back style showed the timing where it should have been.

    I've discussed the dial-back timing lights being used with an MSD 6al box on another site (HAMB).
    Most of the guys reported that their dial-back lights read the timing correctly and compare favorably with a non dial-back light.

    The readings taken on my - owned for a short while, took it back - light was with the dial set at zero and getting the degrees off the degreed dampener.

    A couple things you could do.
    Take a reading with a standard timing light and see how it compares to the dial-back light if in fact that's what you're using.

    The other, time the engine statically at your desired initial advance figure.

    The manuals show centrifugal timing starting as low as 430 rpm in some cases so your 700 rpm idle probably has part of the centrifugal timing in.

    Timing the engine statically would show you where you're at there.

    As far as your cam timing goes, I'm not seeing a crank gear mark other than the yellow or black line in the pic.
    C9

  9. #9
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    Is that a 350 or a 305? They take different timing tabs and yours sounds like it may be a 305
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  10. #10
    pnut is offline CHR Member Visit my Photo Gallery
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    The timing mark on the lower gear is a small circle obscured by the paint pen. I put in a better pic, you might be able to see it. Black mark is the keyslot I marked.

    I have only an HEI with integrated (high voltage) coil. No MSD or dial back light. Using a standard timing light with the marks on the balancer up to 50(double checked against an 8" timing tape).

    You may be right about the centrifugal, but would be surprised if it was that much difference down that low. I will try to get it to idle even lower.

    On a separate note, I noticed my fuel pressure was very low (recent change showing 1-2PSI). I just thought I would mention it in case that had any impact on this. It might even be a bad gauge.

    350 engine. Not 305 (pretty sure).
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  11. #11
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    C9x
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    Thanks Pnut - I see the mark now.

    Are you running a mechanical fuel pressure gauge with isolater for the gauge?
    The isolaters I've been involved with usually make the gauge show 1# low in the 4# - 6# region.
    And if they're full of air or entrained with air bubbles on the gauge side they'll show 1/2# - 1#.

    If you're running a Holley red (street) electric pump sometimes the built in regulator hangs up due to roughness in the bore.

    I had one do that and it stayed at 1/2# - 1# for quite a while.
    I thought the gauge was bad, but nailing the throttle drained the float bowls fairly quick.

    Easy to fix by dis-assembling the regulator and polishing - by hand - the regulator piston bore with some 400 - 600 grit wet/dry.

    Clean well when done and it will pump pressure good as new - provided it was the regulator that was hanging up.

    Most Holley fuel pump failures - and probably other brands - are caused by low voltage at the pump.
    Long run of small wire etc.
    C9

  12. #12
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    Do you have a picture of the front of the engine? timing tag- vibration dampner?
    www.adoptafriendforlife.org

  13. #13
    pnut is offline CHR Member Visit my Photo Gallery
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    I dropped off my Jeep with a friend of mine with a shop. He does lots of carb'd engines and Jeeps.

    While talking to him, I think we figured it out. I checked that the marks on the balancer were right. I DID NOT check if the pointer was pointing to 0 at TDC. Both of us were almost sure that was it (since engine is original, and everything else is aftermarket, they may not line up correct).

    I'll let you guys know.

  14. #14
    pnut is offline CHR Member Visit my Photo Gallery
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    It seems that was it. This is where things get confusing, When I rotated the engine with the piston stop in place, I put a mark on the balancer using the zero on the pointer. I rotated the engine in the other direction, then made another mark on the balancer using zero on the pointer. I suppose I could have used any point on the pointer and acheived the same result which was to check TDC on the balancer.

    To find out where the mark is on the pointer, I THINK what I need to do is to put the piston stop back in, rotate the engine until it stops, mark where zero is FROM THE BALANCER on the timing cover. Then reverse and mark again using zero from the balancer. Then 1/2 way inbetween should be zero on the pointer (or timing cover). Reply and tell me if you think this is wrong.

    In any case, I can drive it for now, and do it next week since I know it won't blow up.

    By the way, here is a picture of the vehicle I have it in (my Jeep)!
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  15. #15
    pnut is offline CHR Member Visit my Photo Gallery
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    Denny, that procedure is exactly what I did the other day. Will that really line up the zero on the pointer and the zero on the balancer?

    If the pointer is off location, how would this procedure show me that? I'm not doubting you, maybe it's just too early for me.

    Drove it in to work this morning, and it ran very strong.

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