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Thread: Spark knock

  1. #26

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    It has 2.64 gears. At 60mph at 2050rpm.. have 3.31 and an 8.8 to put in next year. Need to work on my 68 mustang as well...

  2. #27

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    Is this car equipped with an EGR and is the vacuum line to it plugged on purpose?

  3. #28

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    Quote Originally Posted by gt pony View Post
    Is this car equipped with an EGR and is the vacuum line to it plugged on purpose?
    I think it did have an egr possibly on the bottom of the 2v motorcraft. The air pump is removed and i have everything plugged.

  4. #29
    FEP Power Member Ourobos's Avatar
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    20 year old carburetor, I assume it's fresh now?
    1986 CHP SSP Coupe

  5. #30

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    Does your intake have provisions for an EGR?

  6. #31

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    Quote Originally Posted by gt pony View Post
    Does your intake have provisions for an EGR?
    The ebgine has 10k into it. Name it, it is new. Why would I want egr? Has 1399 heads. Air gap intake. Holley 600 new.(as in rebuilt.
    Last edited by 78futura; 05-30-2018 at 07:38 PM.

  7. #32

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    I re-read the thread. So, there's acceleration pinging, that I assume is worse while driving the car, but will do it in the driveway too just winging the throttle under no load? That's the very odd part. Constant increased (~2000+) RPM pinging too, under load or no load? Wanted to ask, what does "clearanced for drag race" mean? Also assumption until answered/explained: main and rod bearing oil clearances on the loose side... Being that it's happening also under no load, with apparently at least 87+ octane, and compression ratio and camshaft shouldn't generate much more than 190psi cranking pressure, and even if you retard the initial timing all the way back down to zero, TDC, it still does this. If rockers aren't clattering at idle they shouldn't be with acceleration, but worth re-checking your pre-load settings to make sure no clearance has developed and/or is increasing. Mention was made about having to "walk" the plug wires one around the cap to have the distributor where it is... also worth verifying #1 firing is happening where/when you think it is... in investigating this strange problem... good luck with it. ... as well, I agree with you OP, why would you want EGR?, because spark knock/pinging is not an exhaust gas recirculation deficiency.
    Last edited by Walking-Tall; 05-30-2018 at 05:01 PM.
    Mike
    1986 Mustang convertible 3.8L ---> BUILD THREAD
    1983 Mercury Cougar 3.8L LS
    1986 Ford Thunderbird 5.0L ELAN
    1966 Ford Fairlane sedan 200-6
    1966 Ford Fairlane GT (390ci 4spd)
    1981 Mercury Marquis Brougham
    1980 Capri RS Turbo
    1971 Mustang Fastback
    1974 Pontiac Luxury LeMans

  8. #33

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    Quote Originally Posted by Walking-Tall View Post
    I re-read the thread. So, there's acceleration pinging, that I assume is worse while driving the car, but will do it in the driveway too just winging the throttle under no load? That's the very odd part. Constant increased (~2000+) RPM pinging too, under load or no load? Wanted to ask, what does "clearanced for drag race" mean? Also assumption until answered/explained: main and rod bearing oil clearances on the loose side... Being that it's happening also under no load, with apparently at least 87+ octane, and compression ratio and camshaft shouldn't generate much more than 190psi cranking pressure, and even if you retard the initial timing all the way back down to zero, TDC, it still does this. If rockers aren't clattering at idle they shouldn't be with acceleration, but worth re-checking your pre-load settings to make sure no clearance has developed and/or is increasing. Mention was made about having to "walk" the plug wires one around the cap to have the distributor where it is... also worth verifying #1 firing is happening where/when you think it is... in investigating this strange problem... good luck with it. ... as well, I agree with you OP, why would you want EGR?, because spark knock/pinging is not an exhaust gas recirculation deficiency.
    Back in the Jurasic days of early EGR systems, which this vehicle would qualify for, if you disabled the EGR system by plugging the vacuum hose to it, if would create a pinging situation as described because believe it or not introducing recirculated exhaust gas into the intake system would actually cool the intake charge because it was an inert gas. I encountered many vehicles where a mechanic had done this thinking it would help performance or gas mileage. Not so. In fact a fellow tech I worked with was always doing this which fell on me to figure out what was going on until I got to the root cause, which was him. And yes, it did create a problem between us because while I was fixing his f ups, he was making money on customer pay jobs. But I digress ,that is the reason I was asking about the EGR system so I could get a better understanding of the vehicle in question.


    Perhaps I'm suffering some form of PTSD from my past experiences.
    Last edited by gt pony; 05-30-2018 at 07:05 PM.

  9. #34

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    Quote Originally Posted by Walking-Tall View Post
    I re-read the thread. So, there's acceleration pinging, that I assume is worse while driving the car, but will do it in the driveway too just winging the throttle under no load? That's the very odd part. Constant increased (~2000+) RPM pinging too, under load or no load? Wanted to ask, what does "clearanced for drag race" mean? Also assumption until answered/explained: main and rod bearing oil clearances on the loose side... Being that it's happening also under no load, with apparently at least 87+ octane, and compression ratio and camshaft shouldn't generate much more than 190psi cranking pressure, and even if you retard the initial timing all the way back down to zero, TDC, it still does this. If rockers aren't clattering at idle they shouldn't be with acceleration, but worth re-checking your pre-load settings to make sure no clearance has developed and/or is increasing. Mention was made about having to "walk" the plug wires one around the cap to have the distributor where it is... also worth verifying #1 firing is happening where/when you think it is... in investigating this strange problem... good luck with it. ... as well, I agree with you OP, why would you want EGR?, because spark knock/pinging is not an exhaust gas recirculation deficiency.
    Clearanced as in rod main bearings a little looser.
    Rockers sound ok.. The xe274h is known for a little noise of valves slamming shut due to the high ramp rate.
    It does ping more in 3rd gear. Can drive it abd not make it ping if real carefull with the accelerator. Only had it up to 3500 so far. The engine sounds great otherwise. You can tell that 14deg for the inital is the spot to be. It runs smoother at idle and idles up maybe 50rpm right at that spot. That used to be the way to time without a light at a party or whatever..
    You have to stab it one at idle to do the noise(thus making a quick load on the engine) you need 3k rpm at least and at that rpm looking at 30deg probably of total mechanical advance..

  10. #35

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    If I back out of it and hold a certain rpm the noise will go away at any rpm...

  11. #36

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    Quote Originally Posted by gt pony View Post
    Back in the Jurasic days of early EGR systems, which this vehicle would qualify for, if you disabled the EGR system by plugging the vacuum hose to it, if would create a pinging situation as described because believe it or not introducing recirculated exhaust gas into the intake system would actually cool the intake charge because it was an inert gas. I encountered many vehicles where a mechanic had done this thinking it would help performance or gas mileage. Not so. In fact a fellow tech I worked with was always doing this which fell on me to figure out what was going on until I got to the root cause, which was him. And yes, it did create a problem between us because while I was fixing his f ups, he was making money on customer pay jobs. But I digress ,that is the reason I was asking about the EGR system so I could get a better understanding of the vehicle in question.


    Perhaps I'm suffering some form of PTSD from my past experiences.
    Putting in egr gas into the intake lowers the combustion temp helping get rid of pinging. Egr to me is the devil.

  12. #37

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    What should I gap the plugs to? I am at .035" with the suggested afr165 plugs.. anyone have an Idea for gaps to correct a ping? Was thinking of trying .040..

  13. #38

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    Maybe turn the fuel psi up.. its a marshall liquid gauge as they did not have an autometer and could be inaccurate says 3psi..
    Easy to do and test..

  14. #39

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    What 600 Holley carburetor, exactly? LIST #?... because it could be an issue in your situation... as well as a number of 600's that are on the small side for your combination, they can also be calibrated quite (too) lean idle circuit-wise, and therefore the transition, also known as "emission" calibrated... what I refer to as JACKED UP, and don't work worth a hoot on anything even stock besides whatever mediocre weak turd it was originally calibrated on, and worse on something warmed up efficient therefore powerful and completely combusting internal combustion engine. Low fuel pressure... as long as the bowls are being filled, and with off idle and part throttle acceleration, there's not much danger of the bowls being emptied. WOT, maybe different story. 3 or 4 is okay if with bigger 0.120" needles and seats, and some of the fastest vehicles on earth are set up that way to avoid foaming in the fuel... 5-6 is better though with common 0.110" needles and seats... and some 600 Holley carburetors have even smaller needles and seats... and lots of 600 Holley carburetors come with a combination of primary idle feed restrictions that are too small for how much camshaft you're running, and primary idle air bleeds that may be too big... producing a too-lean idle/transition circuit, that will carry further up into overlap with the main circuit, but lean all the same, and CAN produce pinging as well as surging or a feeling like "trailer hitching" slight acceleration/deceleration sensation...

    "Suggested"... What plugs? Maybe they're searing hot...
    Last edited by Walking-Tall; 05-30-2018 at 09:29 PM.
    Mike
    1986 Mustang convertible 3.8L ---> BUILD THREAD
    1983 Mercury Cougar 3.8L LS
    1986 Ford Thunderbird 5.0L ELAN
    1966 Ford Fairlane sedan 200-6
    1966 Ford Fairlane GT (390ci 4spd)
    1981 Mercury Marquis Brougham
    1980 Capri RS Turbo
    1971 Mustang Fastback
    1974 Pontiac Luxury LeMans

  15. #40

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    My plugs are black from all the idling(timing, cam break in etc.) I think they are .097 needles and seats in the float bowls.

  16. #41

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    The kit was for a 4160

  17. #42

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    The more I think about it now seems like a carb issue.. We tued the idle mixtures by vacuum and perhsps with my 2.64 gears and basically setting my foot over the accel pedal is 60mph perhaps the idle mixture is way too lean and the transition causes the lean condition.
    Cutting timing to 0 inital did not get rid of the ping..
    Going to try 3 things both idle screws out 1/2 turn and increase fuel psi and recheck floats.

  18. #43

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    Double post sorry...

  19. #44

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    I agree - likely fuel issue.

    I did notice you mentioning setting timing by ear and leaving it where the motor is up 50 rpm or so. Personally Iíve never used a tach or vacuum gauge when setting timing by ear. I turn it so the engine speeds up, back until it slows back down, then set it to where itís just starting to think about speeding up. Then when I start it I make sure it doesnít crank hard.

    on tolerances, right at or .001 tighter than max allowable tolerance on rods and mains. Front main has accessory drive and needs to be at least .001 tighter to avoid knocking when everything is needing engine power.

    when it was assembled did you check side to side tolerances between the rods and the journals?

    Are you seeing any crank or cam thrust tolerance challenges here?

    Good luck getting this problem fixed!!
    Last edited by erratic50; 05-31-2018 at 09:28 AM.

  20. #45

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    4160 is simply the MODEL number style and tells me nothing about the carburetor at hand. Carburetor LIST #? ... unless it's a secret, lol... tune the idle mixture screws when the engine is up to operating temperature, in gear if an automatic, but turn in very slowly until it slows/stumbles a little bit, and then turn back out 1/4 turn. This will get your idle mixture ideal, but it doesn't really address if the transition is too rich or too lean. Black plugs with just idling or breaking in the cam etc., tells me the idle circuit (primary, or secondary) is too rich, or the primary throttle plates are open too far exposing too much of the transfer slots... the complete opposite of what we're talking about... there should not be black plugs with a fresh engine and carburetor with only a camshaft break-in and some idling and a few miles of driving the thing...
    Mike
    1986 Mustang convertible 3.8L ---> BUILD THREAD
    1983 Mercury Cougar 3.8L LS
    1986 Ford Thunderbird 5.0L ELAN
    1966 Ford Fairlane sedan 200-6
    1966 Ford Fairlane GT (390ci 4spd)
    1981 Mercury Marquis Brougham
    1980 Capri RS Turbo
    1971 Mustang Fastback
    1974 Pontiac Luxury LeMans

  21. #46

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    Quote Originally Posted by Walking-Tall View Post
    4160 is simply the MODEL number style and tells me nothing about the carburetor at hand. Carburetor LIST #? ... unless it's a secret, lol... tune the idle mixture screws when the engine is up to operating temperature, in gear if an automatic, but turn in very slowly until it slows/stumbles a little bit, and then turn back out 1/4 turn. This will get your idle mixture ideal, but it doesn't really address if the transition is too rich or too lean. Black plugs with just idling or breaking in the cam etc., tells me the idle circuit (primary, or secondary) is too rich, or the primary throttle plates are open too far exposing too much of the transfer slots... the complete opposite of what we're talking about... there should not be black plugs with a fresh engine and carburetor with only a camshaft break-in and some idling and a few miles of driving the thing...
    The carb # is not a secret I just dont know it..lAnd the answer for the other guy.. I own a timing light and am using it.

    I live in a small town of 450 people the gas station got 6 pumps 8 months ago.. why am I telling you this? Perhaps the gas is old as takes a year to sell premium..

    Will try and find carb and spark plug numbers tonight..

    Might get a chance to check it out next week..

  22. #47

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    The carb number is this


    http://www.carburetorsrus.com/Holley..._15338094.aspx

    The plugs just pulled them and the electrode looks a bit lean
    Spark plug # ngk(i knkw they didnt have Merican ones!!)
    BCPR5E

  23. #48

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    Ok tried adjusting pressure to 6psi to holleys specs. Checked float level found ok.. at idle in the garage if I wing the throttle I can hear a slight crack sound at about 3k on 3 and 4 cylinder area.. removed cover and checked clearance between the baffle and the rocker and put a dab of assembley lube on and the rocker is not touching when running... removed 1, 2, 3, 4 plugs and found all look the same now black from idling.. maybe 1 of the plugs is bad anyways? Maybe its the sound of the pushtubes slapping against the guideplates? You can grab all the rockers and shake them side to side(twisting them) except when the cam pushes one down.
    Last edited by 78futura; 05-31-2018 at 09:34 PM.

  24. #49

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    You should take a video and post it so we can hear it... Morbid curiosity and all that.

  25. #50

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    Quote Originally Posted by emerygt350 View Post
    You should take a video and post it so we can hear it... Morbid curiosity and all that.
    I wonder if I turn the engine by hand and check all the pushrods on the passenger side and see if and are loose when they are all the way down that would be a good way to check or would the lifter be bled out and not give a good indicator.
    Worst senario a worn lifter or wiped cam lobe but think there would be a miss... best case it is the tranny lines touching the rhs of the oil pan under load .

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