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Timing Questions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Hossbaby50, Feb 14, 2003.

  1. Hossbaby50

    Hossbaby50 3/4 ton status

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    I have been having problems with my truck not running for crap after I installed a new fuel pump. I thought they were carb related, but now I am thinking timing is my problem. I didn't touch my timing so I didn't think it was the problem. But now I am confused about a few things.

    #1: I have the Craftsman Pro timing light, with adjustable timing control on the back. I had been setting my timing with the dial at 0*, and then timing the motor to 10* BTDC. Is this the correct way to do this? This worked fine before I changed my fuel pump, but now it won't. It won't run well now until (with the dial at 0*) I get to at least 20* BTDC. To set the timing should I set the dial to the number I want to set the timing to (12*) then set it on the marker to 12*? Is this 12* BTDC or is this 24* BTDC?

    #2: Right now I am running 12* on the dial, and the motor set to 12*, but I need more timing still. How much timing am I actually running? (sofar the motor hasn't pinged and it is still acting sluggish, especially right off idle if you gas it hard)

    #3: Why would my motor run ok with the 0* dial and 10* engine mark, but now it won't run ok without 0* dial 20*+ mark, or the 12* dial 12* mark?

    I am going to install a new set of plugs this weekend, and aslo pop the cap and see if my mechanical timing weights are stuck or are working properly. I appreciate all the help anyone can give me.

    Harley
     
  2. TopOff

    TopOff 1/2 ton status

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    Your 85 truck, I beleive controls the timing itself. IIRC you should set it to 0 with some electrical connector disconnected at the distributor. Reconnect it, and the timing "computer" takes care of the rest.

    Good luck.
     
  3. Hossbaby50

    Hossbaby50 3/4 ton status

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    Nope, no computer. It did have the ESC for spark knock, but that was disconnected and removed a few years ago. It is set up like a normal HEI distributor. (with MSD) The set timing to 0 thing was for 87 and later trucks with FI I believe. I know that 86 had computer controlled carbs, and some computer controls on the distributor.
     
  4. Doug M

    Doug M Registered Member

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    ? /forums/images/graemlins/grin.gif Your new Sears timing light came with instructions. Read them. /forums/images/graemlins/rotfl.gif Your '85 has a stock vacuum cannister that provides 20 deg advance at idle. When setting base timing disconnect the vacuum hose and plug it. Set base to 10-17 deg btdc, as much as you can without ping while under load. Can't find your instructions? With the vacuum plugged into the distributor adjust knob on timing light until it strobes on tdc. (0) Look at the knob on the timing light that will tell you total base plus vacuum advance timing. (10 base plus 20 vacuum = 30 total)
    2039 and came up with nothing on the search? /forums/images/graemlins/rotfl.gif sorry couldn't resist. A newby with 10 bolts and a carb has no right to talk this way /forums/images/graemlins/grin.gif
     
  5. Hossbaby50

    Hossbaby50 3/4 ton status

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    My instructions are 1000 miles away in Arizona, and I am in Colorado at school. I thought I had read them correctly because it ran fine with me setting my timing to the stock 4* BTDC with the dial on 0*. Now I am having to set it to over 20* BTDC with the dial at 0* to get it to run right after I replaced my fuel pump. This is making me question whether I read the directions right, am setting the timing right. As for the wise ass comments, I expected some for the directions thing, but I have been doing searches on carb, fuel pump, and timing stuff for the past week and a half trying to get my truck to run right. It is my only mode of transportation so I ask questions to hopefully get some help to try and solve my problems so I can get it on the road again, not to get my balls busted. I try and not be some jerkoff that just posts every question I think of without searching, I search, and if I can't find the answers to help me then I ask. I really do appreciate the help though. Thank you for the guidence.

    Harley
     
  6. Doug M

    Doug M Registered Member

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    Hopefully you will accept my apologies. It was not my intention to put you down, too many people are that way these days and I am sorry that after reading what I wrote I was one of them. I hang my head in shame. I was talking about myself on the newby comment.

    Is it possible some dirt or foreign material got into the carb during the fuel pump change? Hopefully not, but if you haven't check/replace fuel filters.

    Your adjustable timing light will read actual timing if the dial is set to zero. If the dial is set on (as an example) 20 and the light strobes at 0 on the timing mark then the timing is 20.

    Be sure your vacuum hose to the distributor cannister is disconnected and plugged while checking the base timing.
     
  7. Hossbaby50

    Hossbaby50 3/4 ton status

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    Its no sweat off my back that you bust some balls. Everyone does. Its no big deal to me, as I don't take it to personal. I just don't like that atmosphere here on CK5, as that is what sets it apart from other sites. I wouldn't hang your head in shame as I wouldn't want you to. I am just defending myself with my comments. I do try and search for info as much as possible, and I advise others to do so too. I have looked, and I couldn't find answers so I ask.

    I do understand how my timing gun works now, (I kinda did before, but was confused). Thanks for the help. I appreciate it.

    Harley.

    P.S. If I ever ask something like "how strong is my 10 bolt" by all means tell me to search, and bust my balls all you want as I deserve it. /forums/images/graemlins/laugh.gif
     

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