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Hot Rods Myth and facts of ignition timing explained

Discussion in 'The Hokey Ass Message Board' started by 2FORCEFULL, Jul 24, 2024.

  1. Paul
    Joined: Aug 29, 2002
    Posts: 16,843

    Paul
    Editor

    nothing is so simple that it can't be misunderstood.
    I learned to time by ear, bring the rpm up to about 3k and twist the distributor to get the highest smoothest speed then back off just a hair.
    now I fuck with everything with every tool at my disposal.
    not much mention of fuel delivery in this thread.
    I find that to be a very important factor in fine tuning the ignition.
     
    jet996, warbird1, chicken and 4 others like this.
  2. Rodney Dangercar
    Joined: May 19, 2024
    Posts: 76

    Rodney Dangercar
    Member

    My turn! ;) I'm not going to say what is right or wrong, I'll leave that to the internet warriors. Before I start I will say that I spent a lot of time under hoods in the 70's and 80's repairing other people crap as a mechanic. When it came to using vacuum, whether ported or manifold or between pre-emission and emission era vehicles, IMO there was no one way that was right. The manufacturers tried all kinds of things depending on the year and what they were trying to accomplish. There are legit arguments for using ported and manifold so I don't get in to that stuff.

    I have a 351W with an Erson HF2 cam, Edelbrock RPM intake, Carter ThermoQuad carb, Hedman headers and ported C9OE-G heads. My timing values are 16 initial, 20 mechanical and 14 vacuum. Lumpity lumpity engine! While I use ported spark for the vacuum advance when up to temp I also have a coolant controlled vacuum switch in the intake that switches the vacuum advance to manifold vacuum when the engine is below 120 degrees. This raises the cold idle and helps the engine run smooth while choked. It works like a champ! It switches off once the water temp is above 120 degrees, dropping the idle back down. I'm off the choke shortly after that and on base idle/timing.

    I have the MSD 6T with adjustable rev limiter and timing adjuster at the dash so I can crank the initial back on a hot day or when it's cold, turning it back up once the engine starts. Since I have a dual point triggering the MSD I also have a backup ignition system I can switch to in case the MSD dies (has happened twice in almost 40 years).

    It works quite well for me.
     
  3. 05snopro440
    Joined: Mar 15, 2011
    Posts: 2,855

    05snopro440
    Member

    My experience is much the same. My dad became a mechanic in a rural area in the 70's. He taught me to use a light to get it close, then move the distributor to get the right characteristics in hot cranking, driving, etc. If you have to remove the distributor and you're not changing anything internally, use a paint pen and mark your distributor, cap, and rotor locations and drop it back where it was. Sure if you're on a dyno or running laps at the drag strip you can dial it in for max performance, but when you're talking a street cruiser, it's not so critical.
     
    Last edited: Jul 24, 2024
    MAD MIKE, 427 sleeper and lilCowboy like this.
  4. lostone
    Joined: Oct 13, 2013
    Posts: 3,447

    lostone
    Member
    from kansas

    ^^^This ^^^^

    Back when I ran dual point Mallory 's then I went to using stock distributors with a Mr. Gasket dual point plate kits and spring kits I would get everything timed then mark the distributor then when I changed or set points I'd just pull the distributor, do the maintenance on a bench where it was easy to do then just drop it back in, line up the marks and tighten her down.

    I did it that way for years....

    ..
     
  5. 05snopro440
    Joined: Mar 15, 2011
    Posts: 2,855

    05snopro440
    Member

    I did a neat one last year... I needed a bit more timing, but my vacuum advance canister was trying to be in the same place as my upper radiator hose (455 Buick). I needed to move the rotor and housing together by 2 teeth. I counted the number of teeth, and divided 360 by that number. Then doubling that angle (for 2 teeth) I figured out the distance I would need to move the distributor and rotor to stab it back in at the right spot. Marked my rotor on the distributor, pulled the distributor, turned it to the new mark, and stabbed it back in. Fired right up and I could get the additional timing I needed. I'm an engineer so the math was easy and I didn't need a timing light, to find TDC, etc. These old engines are really quite simple, sometimes we seem to forget that.
     
  6. gene-koning
    Joined: Oct 28, 2016
    Posts: 5,376

    gene-koning
    Member

    So, lets see what we have learned.
    You can indeed have 50 degrees + timing with a light throttle at 3,000 rpm.
    You don't have over 34-36 degrees of timing at 3,000 with a wide open throttle.
    That is because the vacuum advance goes away when you have the wide open throttle (the intake vacuum has been replaced with a rushing in air/fuel mix).
    Your drag slicks that start at 5psi of air pressure will increase the air pressure after the tires get hot by doing a burnout and a quarter mile run. The "teacher" is guessing that pressure can be 30 psi, but has never checked it. I was happy to see someone point out that the air pressure in the hot tires would be reduced as the tires cool down, (at least that was what I thought he was saying), I'd hate to think someone would think the cold tires would still have the high air pressure the hot tires had. Air pressure will increase with heat, and will decrease with cooler temps.

    Its a great review, but I learned all this in high school auto mechanics class in 1972.

    So, what else have we learned?
    We, on the HAMB are perfectly willing you argue the correctness of these same points we all agree on, because the statements were not worded the same way we would have worded them. Carry on, I'm going to get some popcorn.
     
  7. twenty8
    Joined: Apr 8, 2021
    Posts: 3,454

    twenty8
    Member

    [​IMG] Don't mean to be rude, but I couldn't help but stop listening........:rolleyes::D

    Static timing + plus mechanical advance = "Total ignition timing".
    Then you have the vacuum advance, which is not included in the "total timing". It is expressed as a value in it's own right.
     
    Last edited: Jul 24, 2024
    don colaps, hrm2k, chicken and 5 others like this.
  8. ALLDONE
    Joined: May 16, 2023
    Posts: 3,168

    ALLDONE
    Member

    so page three and not one timing strap pic......
     
    NoSurf likes this.
  9. Fordors
    Joined: Sep 22, 2016
    Posts: 6,294

    Fordors
    Member

    OK, enlighten me, in my 65 years of reading about hot rods and 60 years of being an active participant I’ve never heard the term “timing strap”. What is that?
     
    skooch and Adriatic Machine like this.
  10. F-ONE
    Joined: Mar 27, 2008
    Posts: 3,619

    F-ONE
    Member
    from Alabama

    I think it’s time for a song.
     
  11. twenty8
    Joined: Apr 8, 2021
    Posts: 3,454

    twenty8
    Member

    He would be referring to reading the spark plugs by checking the heat marks on the "earth strap".......
    There is a lot more to it than just the timing though.
    http://www.c5ignitions.com/uploads/1/5/1/5/15151528/spark_plugs_part_2.pdf
     
    2FORCEFULL likes this.
  12. Mike VV
    Joined: Sep 28, 2010
    Posts: 3,329

    Mike VV
    Member
    from SoCal

    2FORCE -

    In red above -
    Not too familiar with FAST, drag racing...are you ?
    LOOK IT UP !!!

    Thanks for the info, but I'll stick with my methods if that ok with you.

    Mike
     
  13. ALLDONE
    Joined: May 16, 2023
    Posts: 3,168

    ALLDONE
    Member

    OK, I'll bite, maybe the 200 mph in a 1/4 mile is not considered fast anymore, or 105 in a 21' boat, but , I still can tune pretty good, and sure ,bench racing is always fun, but not the same.... there a great crowd here with tons of knowledge,.. I think those in the know all agree total all in advance is base timing plus centrifugal mechanical advance in the distributor,,, and that should be all in at 5000 rpms. vacuum hooked up or not.. I always wanna get total at max rpms...make sure I don't hurt something... as far as the 50 degrees advance, that part was explained well by many, and the, lets kick 2FF in the nuts part brought a bunch of entertainment... the reading spark plugs to tune is a major part..
    pretty sure we also agree that once base is set, you can start tuning stuff like jetting, advance curves , vac. advance... Ive run motors alll in with vac advance un hooked to 36 degrees.... then hooked up the vac and the timing would spike.... but don't remember any doing that past 4000 rpms...i've had motors ping with vac adv. hooked up and it would go away un plugged... I'd make note of where, pull the dist. and take it to National Speed in vegas and they would tune the vac and mechanical to my motor...

    so pretty sure those that know here are on the same page,... and those that don't can learn ... lot of good info here..
     
  14. ALLDONE
    Joined: May 16, 2023
    Posts: 3,168

    ALLDONE
    Member

  15. ALLDONE
    Joined: May 16, 2023
    Posts: 3,168

    ALLDONE
    Member

    so you are saying you run over 50 degrees timing @ 5000 plus rpms????
     
  16. ALLDONE
    Joined: May 16, 2023
    Posts: 3,168

    ALLDONE
    Member

    it's the strap on the spark plug that melts off when you run 50 degrees plus total timing right be fore it burns a hole in the piston at WOT
     
  17. ALLDONE
    Joined: May 16, 2023
    Posts: 3,168

    ALLDONE
    Member

    one must keep in mind that we as hot rodders are try'n to attract a crowd into this great hobby sport that were still jumping from nut to nut in 1972... I talk to alot of people ... pretty much get the same answer from most the 30 yr old crowd... they want nothing to do with grumpy old fucks that make fun of you if you have the wrong hub caps.. or your car is not period correct... the rat rod thing started as a revolt to the old crowd to put what ever they wanted on their car, not paint it to some trailer queen to win a trophy..
     
    '34 Ratrod likes this.
  18. ALLDONE
    Joined: May 16, 2023
    Posts: 3,168

    ALLDONE
    Member

    THIS!!!
    this is what I was after, for those that no nothing about Timing but are afraid to ask,... just real facts.. no kick in the nuts, or getting attacked so some one can get more likes....good info!!!
     
    Moriarity likes this.
  19. Fordors
    Joined: Sep 22, 2016
    Posts: 6,294

    Fordors
    Member

    OK @2FORCEFUL , I’d like you to try something for us, put a vacuum gauge on a vehicle with a vacuum advance canister and take a blast down the highway. Note the vacuum reading and report how high, or low the reading was. Then sit down, put your thinking cap on and determine your total timing at full throttle. Don’t attempt to conflate a vehicle running vacuum advance with a fuel car that might run 50* timing in the quarter mile, those are two different animals.
    Sheesh, 40 years in the business and you don’t understand what creates manifold vacuum, nor what the purpose is for a vacuum advance canister on a distributor.
     
    2OLD2FAST likes this.
  20. Been reading these timing dialogs for 50 years in rod mags now on the internet. I am convinced no human will ever know how vacuum advance on a distributor works!!
     
  21. The timing of this thread is spot on, all points have merit.
    I don't want to dwell on it though.
    It has sparked a lot of interest.
    It's like a huge vacuum has sucked all of my previous knowledge about setting the timing.
    Probably time to advance to the next topic, that will spark my interest.
     
  22. GROAN!!!!

    Ben
     
    seb fontana and 2OLD2FAST like this.
  23. MCjim
    Joined: Jun 4, 2006
    Posts: 1,347

    MCjim
    Member
    from soCal

    upload_2024-7-25_8-19-38.jpeg
     
  24. ALLDONE
    Joined: May 16, 2023
    Posts: 3,168

    ALLDONE
    Member

    your not making any kind of sense,, when i time a motor, I know exact where total timing is, a lot of the post on this board to some one that doesn't know might lead them to believe that you put the crank timing at 50 plus degrees,... and that was the reason ,... you wanna think I know nothing about anything, I'm fine with that... but I will keep what I think of you to myself
     
  25. Paul
    Joined: Aug 29, 2002
    Posts: 16,843

    Paul
    Editor

    please be aware excess drama or personal attacks will get a thread shut down.
     
    warbird1 and Bandit Billy like this.
  26. VI Lonewolf
    Joined: Sep 2, 2017
    Posts: 80

    VI Lonewolf

    twenty8 likes this.
  27. gimpyshotrods
    Joined: May 20, 2009
    Posts: 24,403

    gimpyshotrods
    ALLIANCE MEMBER

    The digital engine management on my Falcon frequently has the spark over 45° advanced.
     
    57 Fargo likes this.
  28. Question; if your engine is running great, what difference does any of this make?
     
    egads, 05snopro440 and firstinsteele like this.
  29. winr
    Joined: Jan 10, 2008
    Posts: 296

    winr
    Member
    from Texas

    1965 F100 with original rebuilt 352.... it is around 9 to 1 compression

    "69 hi comp 390 2 barrel cam.. 428/431 intake, exhaust lift
    .198/200 duration at .050 ..... going from memory on the cam

    12 degrees initial advance, 37 degrees total advance around 2700 rpm

    Adjustable advance adds another 10 degrees cruising steady

    Runs on regular,


    Ricky.
     

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