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Hot Rods timing sbc

Discussion in 'The Hokey Ass Message Board' started by dstangl, Apr 14, 2014.

  1. dstangl
    Joined: Sep 29, 2012
    Posts: 28

    dstangl
    Member
    from central MN

    Ok so I got a new distributor and coil and thought I had things in place and fired up the motor it started and actually sounded pretty good but the timing pointer on the balancer isn't where it should be what did I do is the distributor off ? please help never timed a motor before?
     
  2. was it timed correctly before the new distributor? did you change anything else? with different harmonic balancers and pointers it is possible the timing marks are off. i would check for TDC on #1 cylinder , then check your timing marks and remark if necessary . then re-time your motor
     

  3. what is it at now? what should it be?
     
  4. mechanic58
    Joined: Mar 21, 2010
    Posts: 681

    mechanic58
    Member

    A stock (or close to it) sbc should run well and be set somewhere around 10* BTDC. The first thing you really need to do is confirm TDC on your engine and re-mark it on the balancer if you find that the current mark is off.

    A 'good' sbc will run 'ok' with the ignition timing across a pretty wide gap. It won't optimum across that gap, but it will run. For example - you might find that your engine will actually run and even idle ok with the timing set anywhere from about 40* BTDC to as far retarded as 4 or 5* ATDC. It should be set somewhere between 6 and 10* BTDC to be correct with a maximum advance (at speed) somewhere close to about 37* BTDC.
     
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  5. 3banjos
    Joined: May 24, 2008
    Posts: 470

    3banjos
    Member
    from NZ

    If it starts, runs and drives good, never mind where that pointer is. It'll be happy where it's happy.
     
  6. dstangl
    Joined: Sep 29, 2012
    Posts: 28

    dstangl
    Member
    from central MN

    it ran fine before with a single carb and HEI distributor but I have no idea where the timing was it ran when I got it and never changed it then I switched to a tunnel ram and dual carbs which forced me to get a new distributor due to clearance
     
  7. tfeverfred
    Joined: Nov 11, 2006
    Posts: 15,796

    tfeverfred
    Member

    Make sure your harmonic balancer matches the timing pointer. Some balancers were made to read at 12 o'clock.
     
  8. mechanic58
    Joined: Mar 21, 2010
    Posts: 681

    mechanic58
    Member

    Yeah - that's how you end up with egg-shaped cylinders, broken ring lands and a blue haze out the tailpipe.

    Sounds to me like you really might oughta seek some professional help getting the timing set correctly. Running even a few degrees off from where it really should be can have detrimental effects in the long term. The spec exists for a good reason.
     
  9. First, find TDC on #1 cyldr. Mark balancer if needed. Un hook and plug vac adv. line if you have one. Check initial timing at idle. Check total timing and see what RPM it is all in at. Adjust accordingly. Your dizzy my need recurved, to get desired results and optimum performance.
     
  10. tfeverfred
    Joined: Nov 11, 2006
    Posts: 15,796

    tfeverfred
    Member

    There are like 3 GREAT threads on this. All great and thorough. Search them out.
     
    Blues4U likes this.
  11. best advice of any given.

    Forget the number in the book. It is a timing number to make any assembly line engine run. it is seldom ideal even for the assembly line engine, but it will be close enough that they all run about the same. It is a good starting place though.

    I have a question for the OP. What are you using for a timing light? If you are using one with an advance dial find one without it and try again. They are seldom calibrated properly and often the dial gets bumped or turned and forgotten and you don't get a proper reading anyway.
     
  12. 1971BB427
    Joined: Mar 6, 2010
    Posts: 5,612

    1971BB427
    Member
    from Oregon

    No, this is the best advice given! Making sure where TDC really is, and marking the balancer for the correct location is a must. It needs to be done before anything else is done, and then you can pull and plug the vacuum advance to time it.
     
  13. All above is right on.....find TDC, by pulling #1 plug, rotate clockwise looking at damper from front of engine. When you begin building pressure you are on the right stroke. Using a TDC plug would be risky, but using a Flashlight slowly rotate engine toward TDC just when piston stops moving up your close. Mark Balancer with a marker or make a pointer from wire and mount on front of timing cover. Note once you have TDC,.... mark 40 Degrees BTDC by Calculating (2*TT*R)in X(40deg/360deg) = inches. Then you know your timing for the most part should be within this window. 10 to 12 degrees initial, 34-36 deg total advance for street driving. This is what I tend to do, except I use a TDC indicator to find actual TDC. 2 * (Pi) * radius of Damper is circumference of damper. Formula works for any diameter, just remember radius is 1/2 diameter. 40/360 or (1/9) sets upper limit for most SBC's.
     
  14. MAD 034
    Joined: Aug 30, 2011
    Posts: 775

    MAD 034
    Member
    from Washington

    Also make sure you are not 180 degrees off when you drop in the distributor. The camshaft rotates only half a turn to a full turn off the crank. Don't let the "finger over the #1 spark plug compression noise" fool ya. To be sure pull the valve cover on the driver side and look at the position of the rocker arms.
     
  15. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,010

    gimpyshotrods
    ALLIANCE MEMBER

    Disconnect the vacuum advance line, and plug the line. Attach a vacuum gauge to a manifold vacuum source. Adjust your timing by rotating the distributor until the highest vacuum reading has been achieved at idle. Lock it down there.
     
    Last edited: Apr 16, 2014
  16. 1971BB427
    Joined: Mar 6, 2010
    Posts: 5,612

    1971BB427
    Member
    from Oregon

    How would the "finger over the #1 plug hole" fool you? It wont do it on the exhaust stroke, so it has to be the compression stroke.
     
  17. GRX
    Joined: Mar 28, 2014
    Posts: 68

    GRX
    Member
    from MD

    How old is the balancer? Not unusual for the outer ring to loosen on the rubber.
     
  18. MAD 034
    Joined: Aug 30, 2011
    Posts: 775

    MAD 034
    Member
    from Washington

    It will always be on the compression stroke when you hear the piston push air out the spark plug hole but the cam may not be in the correct location. You got a 50/50 chance of being right.
     
  19. woodiewagon46
    Joined: Mar 14, 2013
    Posts: 1,607

    woodiewagon46
    Member
    from New York

    Follow everybody's advice but there is no "exact" degree of timing for a small block Chevy. For example, when you purchase a crate SBC, PN10067353, 1971 thru 1985 the paper work that comes with this engine lists it for Chevys, Pontiacs, Olds, Buick, El Caminos and assorted Chevy trucks. Look up the timing specs for each of these engines and they vary quite a bit. Mechanic58 and gimpys are giving you the best advice. Have you put a timing light on your engine? Where is it timed now? Keep in touch we can get you thru this.
     
  20. Bruskie
    Joined: Apr 9, 2014
    Posts: 50

    Bruskie
    Member

    You didn't say what dist. you r using
     
  21. dstangl
    Joined: Sep 29, 2012
    Posts: 28

    dstangl
    Member
    from central MN

    I'm using a sears timing light that is older than I am no dial or anything on it so I think I'm ok there, vacuum advance is unhooked. I know there are different balancers out there so I made a piston stop from a spark plug and found and marked TDC it fires right up but reads way advanced probably 30 degrees or so at idle where it sounds the best I know motors are all different but with the new rebuilt carbs on there I just want to be confident I have timing where I want it before I start adjusting the carbs I was going to start at 10* BTDC
     
  22. dstangl
    Joined: Sep 29, 2012
    Posts: 28

    dstangl
    Member
    from central MN

    It is a Pertronix Flamethrower distributor and Flamethrower II coil
     
  23. dstangl
    Joined: Sep 29, 2012
    Posts: 28

    dstangl
    Member
    from central MN

    Still battling this the best I can tell my new timing mark for TDC is pretty close even after checking a couple of times timing still way advanced at idle but if I loosen the distributor and try to turn it counter clockwise to retard it closer to 10* as planned it dies way before I get there?
    Since these carbs have been rebuilt and never tuned is that the problem? was going to set the timing before I touched the carbs but it seems to be dumping a LOT of fuel in at idle it smells burns my eyes and has black sooty plugs would all that fuel keep me from backing the timing off?
     
  24. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,010

    gimpyshotrods
    ALLIANCE MEMBER

    Stop looking at the timing mark, and use a vacuum gauge.
     
  25. X2!! Your mark could be anywhere, but vacuum won't lie to you.
     
  26. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,010

    gimpyshotrods
    ALLIANCE MEMBER

    The timing tab, and the groove in the balancer don't have any special, mythical power. Once you have made any modifications to a factory configuration, their relationship starts to lose meaning. Make more modifications, and they will lose even more meaning. Don't make the mistake of being wed to a particular number.

    As I have stated, highest vacuum at idle is a better starting-off point for tuning than some slot, and chunk of metal.

    If you have a late balancer on an early engine, or vice versa, a slipped outer ring on an older balancer, a cheap foreign timing tab, or any possible combination of those, could chase your tail in perpetuity.

    Live manifold vacuum cannot lie.
     
  27. studebaker eric
    Joined: May 9, 2008
    Posts: 1,509

    studebaker eric
    Member
    from Diablo Ca.

    If you can get it to start, with the vacuum advance disconnected and plugged,turn the distributor clockwise(retard) to the point it just starts to slow down, mark this position, or remember it, turn it counterclockwise (advance) to the point it just starts to slow down, mark or remember this point, and set it in the middle of these two points. This will give you a good baseline setting. deal with your carb tuning, and fuel pressure at this point, to get a baseline. Then start fine tuning it.
     
  28. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,010

    gimpyshotrods
    ALLIANCE MEMBER

    Which is the same procedure, just without the vacuum gauge attached.
     
  29. mustangsix
    Joined: Mar 7, 2005
    Posts: 1,296

    mustangsix
    Member

    I think proper timing at 3000 rpm and higher is more critical and lately I've been timing my engines at full advance rather than initial. Unless I've had the distributor run on a machine, I can't know for sure where the timing really is until it's on the engine and running. The springs, bob weights, and stops are often marked, but every one of them could turn out different.

    I'll run the engine up to about 3000 rpm, and with the vacuum advance unplugged I'll use a dial back timing light to set the distributor to give me the full 32-36 degrees I'm usually looking for, depending on the engine. I'll let the idle advance be whatever it lands on and make a note of it.

    This sometimes give me a little more or a little less idle timing than spec, but I know for sure its more accurate at higher speeds where I'm trying to make power. Also, knowing this I can adjust the timing at idle speed and know how far it should move at full advance.
     
  30. monkeywrenching
    Joined: Feb 14, 2007
    Posts: 299

    monkeywrenching
    Member
    from maryland

    Find TDC of #1 , locate best position for dist. Set inital timimg. Plug vacuum line. Then adjust your timing based on this principle: highest vacuum lowest rpm @ IDLE. After that you can work on your full advance given what your engine components will require.
     

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