I'm afraid to drive home. Please help with extreme spark knock!

Discussion in '40- & 55-Series Tech' started by Surveyorsteve, Nov 7, 2018.

  1. Surveyorsteve

    Surveyorsteve

    Messages:
    88
    Likes Received:
    4
    Joined:
    Oct 12, 2016
    Location:
    Ecuador
    I have a 1978 fj40 (on paper) on a frame and with a body tub of a 79 or later. Go figure! I live in Ecuador. Of course that means it is a 'General Population' vehicle with a 2F. No computer, no emissions, no a lot of things. I have been living at 6000-8500 feet but I am am at sea level now and the spark knock is horrible. I need to figure out how I can get home with pistons and valves still working. The carb is an after market knock-off, probably from China, and the distributor may be an older version because it has a plastic cap that screws over the vacuum advance adjustment. When the new carb was installed, the jets were not changed for the altitude and it was gutless. Here it runs good, except under load. Any advice? Can the adjustable vac advance do any good? I have 2 days to get this thing operational enough to make it home, and it's a hard ride for this horse.
     
  2. Zjohnsonua

    Zjohnsonua

    Messages:
    109
    Media:
    24
    Albums:
    3
    Likes Received:
    77
    Joined:
    Feb 1, 2018
    Location:
    Huntsville, Alabama
    We don't know what tools you have your disposal, but I'll assume you can locate a timing light and a set of small screwdrivers. Also, without knowing which Chineseum carb you have we'll be at a disadvantage to give much detail. Having said that:

    Start with the simple stuff. Check the base timing, and reset if necessary. If it's acting up after that then back the idle speed screw all the way out and reset your idle fuel.

    Maybe one of the other guys has an immediate fix for you, but I'd reset the spark and fuel before I tried to get too complicated.
     
    mattressking and Krondor like this.
  3. mattressking

    mattressking

    Messages:
    1,054
    Likes Received:
    1,330
    Joined:
    Nov 28, 2016
    Location:
    Ventura, CA
    All there really is to it. Retime it, set mixture, repeat as needed.

    Without knowing what distributor or carb you have, we can't give much more advice.
     
    GA Architect likes this.
  4. 1911

    1911 chupacabra

    Messages:
    5,165
    Media:
    218
    Albums:
    5
    Likes Received:
    4,738
    Joined:
    Aug 11, 2006
    Location:
    Parker County, Texas
    The base timing has probably been advanced for it to run better at the altitudes you mention. When I grew up in the mountains of Colorado, we did that all the time. Now that it is down to sea level, the timing is too advanced and you are getting pre-ignition. Set the timing back to factory specs if you have a timing light; if you don't, just retard it until the knock goes away under load (going up a hill).
     
  5. dodored

    dodored That ain't your cake Phillip! That's Simones cake! SILVER Star

    Messages:
    69
    Media:
    5
    Likes Received:
    69
    Joined:
    Aug 1, 2018
    Location:
    charlotte nc
    Be sure and disconnect the vacuum advance hose from the distributor when you set the timing so the distributor is not advancing.
     
  6. Surveyorsteve

    Surveyorsteve

    Messages:
    88
    Likes Received:
    4
    Joined:
    Oct 12, 2016
    Location:
    Ecuador
    Now that's the advice I was hoping to find. I grew up without timing lights and such...just an ear. One thing dad didn't tell me (because he'd probably never seen it) is the adjustable advance and how that will affect this situation. Is this something I can use too?

    Signed,
    Ignorant old fart.
     
  7. Dizzy

    Dizzy

    Messages:
    351
    Media:
    4
    Likes Received:
    190
    Joined:
    Feb 5, 2018
    Location:
    Santa Fe, New Mexico
    Octane booster fuel additive, but be aware, it is not easily reversible and does not help unless you are actually kinda lean from altitude, or 92 octane.

    Timing is critical, but even more if you don't have a timing light, or accidentally unseat the oil pump from the distributor. Now, consider why you have knock, pre-ignition might be caused by glowing carbon from running rich, and timing adjustments might not be the best thing to do, retarding it would actually contribute to the problem. Be sure that your choke butterfly is completely open, but if you are actually lean, you can close it a bit, and turn down the fast-idle adjustment screw.

    If you disconnect the distributor advance from the carb, you need to cap it to avoid a vacuum leak on the carb side.
     
    Last edited: Nov 7, 2018
  8. thebigredrocker

    thebigredrocker SILVER Star

    Messages:
    2,704
    Likes Received:
    2,438
    Joined:
    Nov 6, 2013
    So you have an octane adjuster? CDD4BB2B-A8DB-4295-B1E4-A75AB281DAB1.png

    Here’s a link Byron posted: Octane Selector
     
    Solace in Solitude and 73FJ40 like this.
  9. 73FJ40

    73FJ40 After another night of rust removal! SILVER Star

    Messages:
    842
    Media:
    4
    Albums:
    1
    Likes Received:
    612
    Joined:
    Dec 28, 2006
    Location:
    Western Massachusetts
    Likely too late, but @thebigredrocker was on to something.

    If your problem is the result of too much advance at lower altitudes, then adjusting the octane selector is the way to go. Take a good picture of where the 'graduations' are before you get started, then turn the selector in the "R" (Retard) direction for one graduation (10 degrees, according to the linked resource posted by thebigredrocker) and give it a test. If it still pings, go some more towards retard. If it has no pinging, then you will have to advance it until, ideally, the pinging (or detonation) up with matches what the link recommends.

    Once you get back up at higher altitudes, you can then advance the octane selector back to where your picture indicates you've started, and you won't have to worry about how much advance you need after the return to the mountains.
     
  10. Splangy

    Splangy SILVER Star

    Messages:
    6,691
    Likes Received:
    1,122
    Joined:
    Aug 4, 2009
    Location:
    New Hampshire
    The old vac advance distributors are great for being able to adjust the timing by ear with the adjuster sticking out the side of the distributor under that clear cap.
     
    mrboatman likes this.
  11. 65swb45

    65swb45 Elder Statesman Supporting Vendor

    Messages:
    24,041
    Likes Received:
    8,957
    Joined:
    Apr 14, 2004
    Location:
    818-953-9230
    This. Emergencies often end up with bad decision making. Get a timing light before you start monkeying around with timing.

    When I first got my cruiser on the road 32 years ago, I tried to time by ear. Bad idea. Ended up with 32degees...at idle! Fail!!!!
     
  12. cuencanolenny

    cuencanolenny

    Messages:
    1,184
    Likes Received:
    313
    Joined:
    Dec 18, 2012
    Location:
    Cuenca, Ecuador
    I've been living with an FJ40 (2) in Cuenca for nearly seven years. My current unit is a '79, rebuilt '83 2F from an FJ60 I bought in Quito. I am running an Aisin carburetor that I bought new in Cuenca for $380, it isn't good for California from what I understand but I won't be driving to California. I have a newish points distributor that I bought from MAF when I bought their 6-1 Header, they offered a deal. So, at this time it is running a Pertronix II. I have two marks on the distributor, one for altitude and one for the Bullet for going down to Guayaquil. My timing light doesn't show advance so I advance until it stumbles and back it off a bit. The idle, for reference, went from 650 to 950. Dialed that back down and the difference is very noticeable, especially when climbing up to Tres Cruces Pass which is over 12,000 ft. What I found is that the guideline is 1* for every 1,000 ft. of elevation which would put my rig somewhere in the area of 15*. I live and drive mostly here at 8,440 ft.
     
    1911 likes this.
  13. Surveyorsteve

    Surveyorsteve

    Messages:
    88
    Likes Received:
    4
    Joined:
    Oct 12, 2016
    Location:
    Ecuador
    Did you get your timing light here? If so where?
     
  14. cuencanolenny

    cuencanolenny

    Messages:
    1,184
    Likes Received:
    313
    Joined:
    Dec 18, 2012
    Location:
    Cuenca, Ecuador
    No. I was ordering so many parts from the USA for the '70 FJ40 that I bought a timing light and a dwell meter and had them sent down. In hindsight I should have spent the extra money for the advance timing light. But who knew? However, timing lights are fairly readily available, but I've never seen a dwell meter. However, as many on Mud have noted, the conflict between Toyota dwell setting and points gap renders the dwell meter useless, other than as a voltmeter or tach. Where are you?
     
  15. Surveyorsteve

    Surveyorsteve

    Messages:
    88
    Likes Received:
    4
    Joined:
    Oct 12, 2016
    Location:
    Ecuador
    Right now I'm at Solano and 10 de agosto. Been here in town for a couple months. The wife's sick and she's being treated here. Next month we are moving to the coast
     
  16. cuencanolenny

    cuencanolenny

    Messages:
    1,184
    Likes Received:
    313
    Joined:
    Dec 18, 2012
    Location:
    Cuenca, Ecuador
    You are just around the corner. I'm on Carlos V at Isabel la Catolica between Primero de Mayo and Don Bosco. Sorry your wife is ill, hope she gets better soon. Can't imagine living on the coast:).
     
  17. cuencanolenny

    cuencanolenny

    Messages:
    1,184
    Likes Received:
    313
    Joined:
    Dec 18, 2012
    Location:
    Cuenca, Ecuador
    I'm sorry for being brain dead. Do you need to check/adjust your timing?
     
  18. Surveyorsteve

    Surveyorsteve

    Messages:
    88
    Likes Received:
    4
    Joined:
    Oct 12, 2016
    Location:
    Ecuador
    I would certainly like to. Tomorrow we are moving to a different place for our last month here. But after that, could I send a message and set up a time to do that?
     
  19. cuencanolenny

    cuencanolenny

    Messages:
    1,184
    Likes Received:
    313
    Joined:
    Dec 18, 2012
    Location:
    Cuenca, Ecuador
    No problem. lennyledoux and that would be at the gmail. I don't think Mud let's me enter the email, but I haven't tried that in awhile either.
     
  20. Surveyorsteve

    Surveyorsteve

    Messages:
    88
    Likes Received:
    4
    Joined:
    Oct 12, 2016
    Location:
    Ecuador
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.