Quick Help Compression Stroke.

Discussion in '1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-' started by louieb, Jun 20, 2013.


  1. louieb

    louieb Member

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    louieb Member

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    finding compression stroke wile stabbing dizzy.

    ati damper all lines faded. new stock dizzy stabbed right or wrong?


    my question relates to using the metal marks on the stock dizzy and the notched block mark to get close to -10 tdc. the factory does include these mark are they easy to see?

    question to locate the position of number 1 inside the distributor, and line it up with the wire and the case.

    1do you first find number 1 cylinder as air is just coming out of the #1 spark plug with my finger on it? or do i wait till all the air comes out to be on the compression stroke.?

    i noted today as air just exits the #1 cylinder the #1 spark wire on the distributor did not line up with the rotor. it was off to the right. and not lined up with # 1 on the cap, but if i continued to rotate the crank by hand, when all the air from the compression on number 1 spark plug came out, and was evacuated that the wire and rotor did line up with the distributor cap.
    #1
  2. cenok is family

    cenok is family Active Member

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    when the air starts to come out, you are at the bottom of the compression stroke. keep rotating to get to TDC (when the piston reaches the top and the air ceases to come out). this is where you need markings on the balancer to get it to actual TDC, otherwise it's a guessing game and being a little off will make a difference. the rotor should be pointing at the #1 spark plug position when at TDC, not when it just starts the compression stroke.
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  3. louieb

    louieb Member

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    well as far as i can tell, i moved the dizzy 1 notch and put the Number 1 on the compression stroke, when air is almost full at the number 1.

    its seems to be running a hell of a lot better. got back lost power issue i was having.

    since i couldn't get answer here i found a link that told me number 1 should point at number 1 on cap and rotor when air is full at number 1 not after all the air comes out. reason we are now on exhaust stroke. most of my fuel i could smell at the tailpipe, not making power.

    it now makes power and has much more pep. the motor needs spark at 1 when its filled with fuel, not after.
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  4. clement

    clement Founding Member

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    pull the passenger side valve cover while you are rolling it over. problem solved.
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  5. cenok is family

    cenok is family Active Member

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    Like clement said, I assumed you had the valve cover off so you could see when both valves are closed. Both valves closed, piston at top dead center, the pointer needs to point to the #1 post. If it doesn't, you need to restab the dizzy. being at top dead center means the piston is at the top of the cylinder, so if by "air is full at #1" you mean the cylinder is full of air and the piston is low in the cylinder, that is incorrect. All the air will push out past your finger on the spark plug hole as you approach tdc. I know how an engine works bud, but thanks for the lesson
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  6. louieb

    louieb Member

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    thats the way it was, and i mean when the compression is strongest on your finger.

    i dont know why its running better but it seemed to work. your quick to reply when u have a wrong answer. your right as far as ai canw2 tell by other web sihts describing it, but the one i found said it should be this way. tdc is not the same thing as compression stroke is it? when the spark fires? is it?
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  7. jetmech807

    jetmech807 Mustang Master

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    TDC is the very top of the compression stroke. The point where the piston stops before moving down on the power stroke. You generally set the distributor to fire the plug x amount of degrees(crankshaft degrees)before TDC. That would be advance. I have no experience with Fords with distributors so I don't know how much advance they like. My 03 is the first Ford I've owned. The method I used for Oldsmobile was bump the starter till compression blew my finger off the #1 spark plug hole, then line up the timing mark on harmonic balancer with 0 degrees on the pointer. That is TDC. If you have a balancer that has slipped over the years, that doesn't work though. Beyond that, break out the timing light to fine tune your advance. There, you should be thouroughly confused now.:D

    Sent from my EVO using Tapatalk 2
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  8. louieb

    louieb Member

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    think about this, the way every 1 has described it here is the way i set it a year ago. i was very disappointing. the car had seemed to looses 50 to 75 hp, but i ran it.

    yesterday i was readjusting valves, and checked my mark. but i didn't like the idea of the ignition fire at tdc. so i moved it to the position were my finger feels strongest pressure, not an empty cylinder, and the car picked up the 50 to 75 horse power that was lost. the exhaust sounds better during shifts. no popping. less fuel smell.

    faster smother acceleration. at this point i dont know what to think. i will be timing total advance today at 2500 RPM and see how that goes.

    now im looking at the mark on distributor, and block they line up.

    this should put me close to 10 degrees before. i am running it now at 14. the rotor lines up with number 1. wire and cap.

    at this point i could try turning motor. and rotating the crank a little more, getting all the air from number 1 plug.

    is it necessary? considering the distributor lines up with block, and im at least close to 10?
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  9. cenok is family

    cenok is family Active Member

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    Tdc is tdc, regardless of which stroke you are on. Doing the method I said, and 99% of everyone else, is the only way you can get an engine timed correctly, unless you marked the dizzy and block, make sure the engine never rotates, and stab the dizzy back in exactly where it was before. After that, you can adjust spark timing to fire X degrees before (advance) or after (retard) tdc. Your timing depends on your setup. N/A setups run better with advanced timing, around 10-16* base 32-36 total. Forced induction typically runs 14-18 total.

    Btw, I didn't mean to seem snappy, I just know I'm correct on this situation.
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  10. cenok is family

    cenok is family Active Member

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    if it seems to be running correctly, no need to do it again. I see you are referring to marks on the dizzy and block so again I'm going to assume you made the marks, pulled it, then put it back in the same way? If that's the case, you should be fine. It'll be timed at whatever it was before and you can advance or retard from there. You'd know if the timing was off, if you picked up power, it sounds like you had too retarded before.
    #10
  11. 7991LXnSHO

    7991LXnSHO Active Member

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    There should be a tdc mark on the harmonic balancer. If it does not line up with the point both valves are closed and the piston is at its absolute highest, something is slipped or put together wrong like the marker plate in the wrong spot or even the wrong tab. A cam shaft could be put in 180 deg off or the balancer outside could move and you might blindly get it to run. You need to reference 10-14 deg. advance base timing from the real tdc mark. The computer on your Mustang, or if it was an older Olds, the mechanical and vac advance parts in the distributor, control the rest of the advance curve.
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  12. mikestang63

    mikestang63 Mustang Master

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    Not saying this is the case, but if you have the stock harmonic balancer, check to see that the rubber ring which is in between the inner and outer portion is not sticking out or shifted. That would cause your balancer to be off resulting in the timing marks to be off, and the car to lose some power. Since you did not describe any shaking or vibrations I doubt that is it but it could have shifted just a bit.
    #12
  13. 7991LXnSHO

    7991LXnSHO Active Member

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    Did you get it all straightened out?
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  14. cenok is family

    cenok is family Active Member

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    is should have been an easier task, but he said in his original post that he has an ati damper and all the lines are faded away.
    #14
  15. foxfreak89

    foxfreak89 New Member

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    Im new to the site but i need help identifying the cam i pulled out of my car on the heel its marked with 6111 i cant find ANYTHING on it though
    #15
  16. mikestang63

    mikestang63 Mustang Master

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    How about starting a new thread instead of hijacking someone else's? Have you tried those new Cool Ranch Dorito's Tacos?
    #16
  17. foxfreak89

    foxfreak89 New Member

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    I dont know how
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  18. 7991LXnSHO

    7991LXnSHO Active Member

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    I see that. A new 0 (tdc) deg mark would have been easy to mark by now. New timing tapes are cheap. So if he now understands how to set the timing advance from the true zero mark, he is probably too busy driving to post a result.

    If he is cheap, he can do some geometry to figure out where to mark/scribe 10 12 and 14 degrees advance for free. Take the diameter of the balancer, change the measurement to circumference, device it by 36 (360 deg * 10) to find the distance to 10 degrees new mark, etc.

    This is the only reason they teach high school math - so we can fix cars better. :)
    #18

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