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Posts posted by datzenmike

  1. Vacuum advance port should be just above the throttle plate when closed at idle. There should be no vacuum advance at idle. However as the throttle opens the plate rises up to and above the port and  intake vacuum is felt. As the plate opens farther the intake vacuum begins dropping and at WOT there is almost none at the port.


    That said, the vacuum port is above the throttle plate but the outlet pipe might be anywhere. Someone who has one would know.

  2. Looks like the external regulator is bad and needs replacing. Cheapest this is to just replace it and keep going. Alternatively (pun intended) you could get a '78 or '79 620 alternator that is internally regulated and get rid of the external one. Only down side is that it's only 36/38 amp output. Car alternators have 50 amp output but are larger diameter and a tight fit.

  3. Tire width and height is not determined by the rim size. Your 195/75R14 is 25.5" tall and 7.7" wide. A 195/70R15 is 7.7" wide and 25.7" tall. Almost identical except that the rim diameter is different.


    You can go wider on 14" rims, even if only 6.5"wide.  Taller is a bad idea as it effectively lowers your differential ratio. This reduces your acceleration and performance not to mention the speedometer error. 


    Your 195/75R14 is 25.5" tall and 7.7" wide. A 245/60R14 is 25.6" tall but 9.65" wide. That's 2" wider than what you have but has no effect on speedometer or performance.

  4. Looks fine. I love finding an engine with bright green coolant in it. If you don't know when it was changed last.... change it now. Get a good name brand anti freeze and use distilled water that is free of dissolved minerals. If hoses need replacing (usually they rot from the inside out and it's not obvious) and have swollen or gone soft do that first. There's nothing quite like loosing all your coolant from a blown hose and changing it in the snow.

  5. As you probably know the Z24 is famous for blowing head gaskets for seemingly no reason. Usually at 100k intervals. It's a combination of age and heat cycles and the gasket compressing. Only 'cure' is replacement once blown BUT you can do something to avoid it by re-torquing the head bolts. The procedure is, on a cold engine, to loosen one bolt several turns and immediately tighten to 60 ft. lbs. Then on to the next bolt. Any order you like as long as only one bolt is loose at one time. This keeps the head securely clamped down on the head gasket. Check them once a year. I'm not saying this is a problem right now but this is a preventative measure that should be used as soon as possible.




    Reluctant starting could be timing too advanced. Try checking and setting to 3o BTDC. You can run +- 2o on this if it helps.



    Set check the valve clearances.



    The idle mix screw is set and sealed at the factory but a 1/8" drill and a wood screw will allow you to pull the aluminum plug out to get at the adjustment screw. A lean-ish mixture can misfire so try turning the screw out in 1/8th turns and see if it helps. Keep track so you can put it back.




    I'd say it idles pretty good!

  6. It broke because you used a too long bolt that bottomed out.


    Myself I'd get a replacement coming..... then I'd glue it together with JB weld and put the top cover and bolts in to hold it till set. It would get you going while waiting for the 'new' one to arrive. Definitely needs replacing.

  7. It may be that clear because the leak is so bad it keeps getting topped up!!! A rolling oil change. 😄


    Engine oil. For this you really should do some research on the ZDDP controversy. ZDDP is a zinc anti scuff additive added to the oil but in the last decades oil makers have been dropping the levels from 1,200 PPM to as low as 600PPM for two reasons. Most engines today use roller cams and don't need the protection and it's harmful for today's catalytic converters so they are slowly fazing it out. Our Datsuns are 40 plus years in the past and were designed to use oils high in ZDDP. Primarily to protect from cam to tappet or cam to rocker scuffing. Oil companies have said that today's oils are reverse compatible and that the levels in the past were too high to begin with so lowering them does no harm.


    Me? I say it's too late when my L20B cam chews up the rockers, so.... no thank-you. It's easier to just use oils that are still high in ZDDP. Such as? Well diesel engines are mostly push rod and use tappets and are exempt from using the lower level ZDDP. I'm using Shell Rotella T4 15w40 although you can get it lighter in 10W30 as well. Chevron Delo 400 is also good as are any over the counter racing oils, usually marked with an R. Just ask for a 'flat tappet' oil and the counterman will know what you mean. You can also buy ZDDP additive but really? why not just buy a diesel oil. Synthetic? Over kill protection you'll never ever need. It may also begin leaking from old seals that easily contain conventional oil but can't handle the thinner slippery synthetic.


    So do some research and make your decision based on knowledge. I did, and get a good night's sleep.

    • Like 1

  8. With practice you can do this so smoothly no one will even be able to tell what you are doing.


    You'll have to measure the booster hose size. Be sure it's a thick wall suitable for extreme vacuum that might crush a heater hose. I'm guessing most N American car and truck brake booster hoses are all the same size. If not try something from a later Nissan. Try a wrecking yard. Take note that there is a one way valve in line on that booster hose.

  9. 10 MPG is not possible but 10% is. You don't need a belly pan for 10%..... just driving differently will do that. Simply practice driving without using your brakes. Every time you brake you are throwing away the gas you just used getting up to speed. Look ahead and watch for stops or slow downs and slowly slow down trying to keep the vehicle rolling. Space yourself out in traffic so you don't have to use the brakes as much. Accelerate slowly, WTF? don't be in a rush, there's no reason to rush, leave 5 min earlier. Avoid short trips when the choke is on. Keep engine in tune. Empty out your vehicle of junk that you pay gas for hauling around. DRIVE THE SPEED LIMIT... Going 60 MPH uses 4 times the gas going 30 MPH, not twice the amount! Even 5 MPH makes a difference. The difference driving 100 miles at 55 rather than 60 is less than 10 minutes. Keep tires inflated closer to max than min air pressure. Keep a log book of gas and mileage and calculate it every fill up, this keeps you engaged in getting better mileage. Any sudden change can indicate a problem that can be fixed.

  10. 9 hours ago, Scrapson said:

    So don’t dump the clutch just let it slowly choke itself out. I figured as much. My baby is back my girlfriend is gonna be pissed when I spend a day cleaning it. Alright that sounds a lot better. It never did diesel before any of this happened besides when I first bought it. I gotta adjust the idle thing though I don’t like how it goes from 600rpm to 1500


    Not exactly. Load the engine down with the clutch, then turn ignition off and it will stall. Hold the brake so the truck doesn't creep or jump ahead.

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