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Posts posted by datzenmike

  1. It's been quiet and reliable and greatly improves driving pleasure. I certainly don't want to hurt it by continuing to drive it if something IS wrong and will try to open it up and see. But before this, will check the driveshaft and differential. Seems to get loud right where you transition from load to coast. Right when the drive train is slack. But has to be at high speeds. 


    I see that I have a Z series 5 speed in my parts pile, from a trade. It's pretty much identical and a mid ratio just '83 or '85. Definitely not a later one as it has the 56mm counter bearing. I'd like to try the '85 CA18ET converted to L series bolt pattern. It's probably the last update improvement to the 71b 5 speed before they were retired in mid '86. It's a wide ratio and may take some getting used to. If I don't like it, it will still work for road trip traveling and I always can use this mid ratio spare or fix the problem with the current 5 speed. 

  2. Just because something makes noise doesn't necessarily mean it needs replacing. Something else may be causing this.



    It looks like the fuel shut off switch. It's activated by intake vacuum. Does it have 3 wires to it in the back? If it does, check that the small hose to it does not have any cracks in it and that it is firmly connected.


    If it is the fuel shut off, it's job is to temporarily shut off fuel to the idle circuit by opening the idle cut solenoid during deceleration when intake vacuum is highest and the throttle is closed. Idle fuel when the throttle is closed is not needed to keep the engine running and is simply wasted out the exhaust as a hydrocarbon emission. There is a clutch switch in line as well so the engine does not stall during a down shift. Long before the engine gets to a lower or idle speed, the vacuum signal lowers, the fuel cut off switch closes, the idle cut solenoid opens and fuel for idle is returned. It's an emissions device that actually saves gas and only works when you are slowing down suddenly. 

  3. I don't know what the 'noise' is at high speed but it's quiet and silky smooth around town. This weekend I raise her up and check a few things, but probably out she comes. The 5 speed in there is the greatest one I have ever had. Pulled from a scrap metal yard, used in my 620 for 10 or more years, now in the 710. Mid ratio box with 4:11 differential just a perfect combination.

  4. OK milling the case is a problem as there isn't anyone near me capable of it... so, I have a new in the box 56mm Nachi 'Made in Japan' bearing. This is more than enough for now.




    Pulled off the 62mm and saved it. The 56mm tapped on with a 4 lb mallet with little effort. Then switch to a suitable pipe and driven home. Had to clean up the 280zx cover plate and swapped the less rusty clutch arm pivot onto it. I guess a home made gasket is in order.


    Still to do is drill out the first/second shift rod to 16mm or 0.6304". A 5/8" is 0.625" I imagine it will wobble a bit and be oversize 5 thou anyway.


    I ordered a new rear transmission seal and a front cover seal.... they should be in by Friday. This is a long weekend with Canada Day holiday Monday. I don't see why I can't get this bad boy swapped in.



  5. Going from a 32/36 to a 38/38 is not the way to fix an idle issue. Carb size has little to do with the idle, they both pretty much adjust the same way. Perhaps the 32/36 needs to be cleaned out. Increased cam overlap extends the time both the intake and exhaust are open at the same time and this lowers the intake vacuum and a poor idle and low speed is the result. Too much carb and too much cam is usually hard to live with.



    You mention the timing. Would this be ignition or cam timing as they are completely separate things on this engine.


    The cam timing is usually set on the number 2 hole on the cam sprocket. The other hole is only for adjusting out chain stretch or if your head was milled down. Stretch or milling will cause the cam events to happen later than they normally would. Moving to the #3 hole advances the cam timing about 4 degrees.


    Ignition timing is set by adjusting the distributor and should be around 5 degrees.


  6. My 521

    Electric chokes will open (but not fully) by themselves just from engine heat. Will not run well, but will run. If set right the fast idle will still be on and this is what alerts you something isn't right.

    • Like 1

  7. Intake is directly from the ignition. Exhaust is from ignition through a fuse. They should be 12v each, just a weird way to do it. Try 12v directly from the battery. (maybe just old wiring) If nothing swap the coils around and see if the problem switches.

    • Like 1

  8. Perhaps the coil was replaced?


    The intake coil is run directly from the ignition switch. The exhaust from the first fuse on the left side of the fuse box. Wire 12volts directly from the battery to the + side of the exhaust coil. If the spark improves then it's not getting full voltage. If no change, witch the wiring between the coils. If it switches to the intake side the module under the rotor in the distributor may be at fault.


    Always run the dual coils. They both fire together and like burning a candle at both ends it speeds up the burn time.This in turn allows the timing to be much less than a single coil and less chance for pre-ignition. All engines would have dual plugs if they could. Look at the fastest 1/4 dragster engines they almost all have dual plugs.



    • Like 1

  9. The center support bearing rarely needs replacing though some have done this. Only one confirmed case of a failed bearing by Metalmonkey that I know of. The bearing merely supports the rubber isolater ring around it and carries very little load. Don't be surprised if changing this has no effect. Usually the rubber rots away and the driveshaft is free to flop around and vibrate. If it's noise or vibration it's almost always one or more of the 3  U joints.


    The driveshaft is balanced as an assembly so be sure to mark everything so it goes back in the same orientation.

  10. Get that thermostat changed so you have a consistently warmed engine. A 180 should work in Florida if the cooling system is ok. Gauge should read about in the middle maybe slightly above half.


    I would think a 5 plug is a bit cold, try a 6.  

    • Like 1

  11. Not shown, but the zx box had the groove and the pinch bolt for the column or rag joint connection. It could only go on one way. The 620 and zx pitman arms had four black sections on the splines. The pitman could go on in only 4 positions, two (90 and 270) were obviously to the sides. 90 and 180 were equally obvious front and back facing

    • Like 1

  12. Fusible links are to protect in case of a catastrophic grounding of the electrical system in a severe accident. It 'blows' like a fuse rather than the wiring lighting up like a toaster. The great thing about a fusible link is that they don't blow instantly so a sudden brief surge doesn't hurt them. They do take 5-10 seconds to fail and the Hypalon coating will melt but is resistant to burning.



  13. Found a spare shifter to mess with. I did this mod last summer but was conservative, This time I'm maxing out the fulcrum height to get the shortest throw but retain the same shifter height. Looks like 7/8" higher and a 23/64" drill




    Cut and weld.





    Tried to put the CA18ET tail onto the zx box to check the shift length, and whada ya know... the striking rod width was increased so it won't fit into the hole on the adapter plate. Well that's one more thing different on the '85 and up 71Bs. Larger 1st 2nd shift rod, larger counter bearing, and larger diameter striking rod..


    So it has to go on the CA gears anyway so I fit it and got it on the first try. It's on loosely so when I'm ready I'll crack the rear case and squirt some Honda Bond or w/e it's called in when I mount the modified L series front.


    Shifter travel is now 3.5" between 1,3,5 and 2,4 R.


    Shift effort is minimal in every gear but 5th and reverse. I tried everything to make it easier but it requires a hefty tug to get it out of 5th or reverse. The last thing was to remove the plug covering the detente ball on the 5th/rev shift rail and suddenly it was free to move. I settled for trimming the spring till it was just like the other 4 gears. If this turns out to be a bad idea I have plenty of 71B springs and can replace it. Maybe it just needs to be driven. The other thing is mechanical advantage id lost by raising the fulcrum point so I may have to live with it.

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