Register now to get rid of these ads!

Hot Rods Myth and facts of ignition timing explained

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

  1. skooch
    Joined: Feb 7, 2007
    Posts: 688

    skooch
    Member

    Wow, I thought spark retardation was started in the 70’s.
     
    Sharpone likes this.
  2. V8 Bob
    Joined: Feb 6, 2007
    Posts: 3,132

    V8 Bob
    ALLIANCE MEMBER

    If you didn't retard a crank start Model T or A, you may have ended up in the hospital!
     
  3. warbird1
    Joined: Jan 3, 2015
    Posts: 1,297

    warbird1
    ALLIANCE MEMBER

    kadillackid, Sharpone and V8 Bob like this.
  4. V8 Bob
    Joined: Feb 6, 2007
    Posts: 3,132

    V8 Bob
    ALLIANCE MEMBER

    [QUOTE="mike liebenberg,......any advice would be appreciated[/QUOTE]

    Mike, a slipped crank damper has been suggested and I've asked for point dwell. One or both will cause the problems you are having.

    When I bought my flathead '51 Ford, the engine ran, but not good. When home, timing showed 15* or so BTDC but dwell was also waaay off. Reset points to 27* and set timing to stock 2* and engine ran like a new one.

    I bought a healthy 312 that ran good, but could never set timing ever close to spec, until I found the damper had slipped, very common on Y-blocks I learned later.

    I suspect one or both of above could be your problem. The other common Y-block issue could be the timing chain not set to the 12 pin spacing.
     
    Sharpone likes this.
  5. And even cars from the '10s and '20s had mechanical spark advance. Actually a manual spark advance. In the form of a lever sprouting from the side of the steering column. Street driving a vehicle without some means of readily advancing or retarding the timing as needed would totally suck. :(
     
    Sharpone likes this.
  6. twenty8
    Joined: Apr 8, 2021
    Posts: 3,454

    twenty8
    Member

    I am interested to hear what happened as well......
     
    pprather and Sharpone like this.
  7. Dwell is 38
    And again the vehicle is all original with the Teapot carb and the non mechanical advance dizzy.
    What i'm trying to get feedback on is why this all original set up now prefers a static advance of 22* then shows the vaccum advance kick in showing around 44* revving no load. Idle vaccum healthy 19inHg and cylinder compression at around 105psi per hole. And it has a solid front crank pulley of which i have verified has correct TDC mark by confirming cylinder 1 is at top of bore with pointer lining up we pulley mark.
     
    Sharpone likes this.
  8. lostone
    Joined: Oct 13, 2013
    Posts: 3,447

    lostone
    Member
    from kansas

    Could there be some excessive slack in the timing chain ?

    ...
     
    Sharpone likes this.
  9. Are you working with a "fixed" timing light or do you have one with a dial and gauge built into it that allows you to adjust where your timing mark indicates "zero" on the timing tab?
     
  10. V8 Bob
    Joined: Feb 6, 2007
    Posts: 3,132

    V8 Bob
    ALLIANCE MEMBER

    Your dwell is WAY off, throwing your timing off. Dwell directly affects timing. Reset dwell to 27, then work with correcting timing.
     
    warbird1 likes this.
  11. New timing chain set up
    Using a adjustable style timing light...thats how i know i'm getting 44* total vacum timing.
    And have tried adjustments of between 28 to 38 degrees of dwell
     
    Sharpone likes this.
  12. gene-koning
    Joined: Oct 28, 2016
    Posts: 5,376

    gene-koning
    Member

    If you really are running 44 degrees of total advance, you won't be doing it very long, that motor is not designed to have that much spark advance.

    The dwell on a v8 has to be very near 28 -32 degrees. More or less will mess up the timing. Dwell is the number of degrees the points are closed, when the points open, the spark gets discharged from the coil. If your actual dwell is 38 degrees, then that spark is being sent out pretty late, that is why you have to advance the timing so much.
    Set the dwell at 28-30 degrees and leave it there.

    [QUOTE="V8 Bob,
    The '49-'53 flathead max distributor advance was around 10 degrees from about 4" Hg input, resulting in 20 or so crank shaft degrees.
    The '54 Y-block max distributor advance was around 15 degrees from about 4" Hg input, resulting in 30 or so crank shaft degrees. Later '55-'56 Y-block specs are similar.
    Sorry for any confusion.[/QUOTE]

    You have a higher vacuum reading then these specs show, so its possible that you have more vacuum advance. The above spec shows your total advance should be around 30 degrees, so an initial setting of 15 + the vacuum advance should give to a motor that performs properly. You may adjust a couple degrees up or down to give you a good balance between a hot start and performance.

    Your old initial timing of 8 degrees was too slow, but your 20 degrees was too much. Seems like someone told you that very early after your 1st post.
     
    Last edited: Oct 14, 2024
    firstinsteele and Moriarity like this.
  13. So gentlemen i hear all the specs and actually have the following page in my original manual. What i'm facing is a vehicle that will not run on the factory spec and i'm trying to find the reason. It will not run at 3* 0r 15* as it just spits thru carb. I set timing old school way using Vaccum gauge by finding that sweet spot and lock in down. Then using the timing light just to verify where it's happy and it's the 25*. Road test it and no pinging ,spitting or backfire. But then i face the issue of not starting after hot soak. Yes i can live with it but getting it right is always the right path.

    7EF7295B-405A-4CBA-8F11-B21D6CCA93CA.jpeg
     
  14. gene-koning
    Joined: Oct 28, 2016
    Posts: 5,376

    gene-koning
    Member

    If its not starting right, then its not happy at 25 degrees, You are happy with the performance, but its not happy with the advanced timing. Its advanced too far. Is your dwell set correctly?
    Back off the timing until it starts easy, then see what the timing is set at, and tell me how much vacuum you have lost by dropping the timing back. Still a long ways between 15 degrees and 25 degrees.

    I believe you need to look into why its spitting back through the carb with the reduced timing. Spitting through the carb is not generally an issue with having the ignition timing set at factory specs unless the valve timing is off. I would expect spitting through the carb to show up more with too much advance rather then not enough. You likely have a lean condition or a different problem, like an intake valve not closing fast enough (carboned up or dragging valve). Or, maybe the starter, starter wiring, or battery isn't up to par causing the hard hot start condition, but I still think 25 degrees static timing is too much. Couple the advanced timing with the hot restart issue, your motor is agreeing with me.

    Timing has always been a compromise between starting and performance, and the specs in the book are a starting point.
     
  15. ALLDONE
    Joined: May 16, 2023
    Posts: 3,168

    ALLDONE
    Member

    not really, there's was nothing to do....fact is this.... this is how you set timing...hook up the light... start the motor, point the light at the timing mark and turn the dist. till the mark lines up to factory spec... probley some where between 8-12 degrees... the rest doesn't matter unless your trying to squeeze some free hp... if the book say set it at 8 degrees... set it at 8 degrees... there is not a shop manual on the planet that says set it at 50+ degrees... thats the facts... but one time at band camp.......................is just gonna confuse those that wanna know how to set timing...
     
  16. ALLDONE
    Joined: May 16, 2023
    Posts: 3,168

    ALLDONE
    Member

    so lets say you made the mistake of taking this to my shop.over fourty years same location, 5 star shop.... but we don't know anything, and never learned any thing.. but we say open for someting to do...

    the very first thing I would do is pull #1 plug... bring the motor to top dead . and look at the timing mark... could be some one it marked at total timing... or what ever the case...you need to know this first...then I would put the plug back in and hook up the timing light...start the motor and see where it's at at Idle....then I would bring the rpms up to see if the dist. is advancing... could be stuck either way full adv. or no advance...till that is verfied your just chasing your tail... spinning your wheels, waisting time...
     
    firstinsteele likes this.
  17. ALLDONE
    Joined: May 16, 2023
    Posts: 3,168

    ALLDONE
    Member

    the next thing, I would tell you to make sure you put a quart of marvel mystery oil at every oil change...with out it you get problems like you mention...the valve train get gummy and likes to hang valves open... and if I was working on it I would do a compression test... poping through the carb is what happens if a intake is hanging open,, and stick when you shut it off... then makes it almost impossible to start...and like said, i would verify the accelerator pump is working and the choke is open... mosty basic y block stuff, which i know nothing about , but I like to type stuff on web sites to make people think I know stuff....guess I get lucky cause all my cars run good...
     
    patsurf likes this.
  18. I'm going to respectfully bow out of this conversation
    thanks
     
  19. ALLDONE
    Joined: May 16, 2023
    Posts: 3,168

    ALLDONE
    Member

    did you fix it???
     
    warbird1 likes this.
  20. ALLDONE
    Joined: May 16, 2023
    Posts: 3,168

    ALLDONE
    Member

    heres another thing about 6v and y blocks, and other 6v cars... a big thing is the battery...need to load test it...if it bombs to 3 v when you crank it, that makes the spark too weak,.. and FSI dist. won't spark at all...but. of all the 57 t birds my wife has had the marvel trick has fixed the hot start issue...
     
  21. ALLDONE
    Joined: May 16, 2023
    Posts: 3,168

    ALLDONE
    Member

    also to those reading this looking for answers....sometimes you are just over looking what the problen is....I had a guy chasing a hard start problem once....he replaced every thing.... ran the timing to the moon.... I smelled the gas...ahhh, how old is this gas??/ put new gas and it ran perfect...
     
    warbird1 and Eric David Bru like this.
  22. ebfabman
    Joined: Mar 10, 2009
    Posts: 582

    ebfabman

    Small block Chevy in a 51 Merc. AFR in the mid to high 14 to 1. IMG_7465.jpeg
     
    Rice n Beans Garage and pprather like this.
  23. Thank you @ebfabman.
    Light throttle, 21"hg vacuum.
    Cruising 72 mph at 2220 rpm.
    Timing at 48 degrees BTDC.

    Initial advance, some mechanical advance and some vacuum advance.
     
    Last edited: Oct 23, 2024
    Rice n Beans Garage and ebfabman like this.
  24. ALLDONE
    Joined: May 16, 2023
    Posts: 3,168

    ALLDONE
    Member

    and just to keep with the facts... timing was not set @ 48 degrees... it saw 48 when it wasn't producing any poewer, and the motor was just floatin... also fact... which would be nice if it was shown...is that every time you touch the throttle ,the timing will drop 15 degree...kinda like the instant MPG on new cars... my class C rv got to 99 mpg pulling a 10k loaded trailer down the 8% grade in hurricane utah. but soon as Got to the bottom and had to gas it on the flat it dropped to3 mpg.... but just to not argue with the sign post and take the wrong road home....I never tell anybody I get 99 mpg pulling a trailer...same as one should not tell others they run 50 degrees advance,... the motor is asleep when it gets to 50 degrees ...
     
    Fordors likes this.
  25. ebfabman
    Joined: Mar 10, 2009
    Posts: 582

    ebfabman

    IMG_7481.jpeg

    Wrong. I set it at 48 degrees and can change it in real time any time I want.
     
  26. ALLDONE
    Joined: May 16, 2023
    Posts: 3,168

    ALLDONE
    Member

    you win....
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.