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z20 swap.


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Like above says. Ive looked it up but it got confusing due to the conversation was about using a block. So here goes.


My L16 is giving up. My mpg's went out the window. It wont stay on at a stoplight when my lights are on. And it takes about 10+ minutes to start up. I have a new exhaust no leaks. I checked the carb everything is good and i replaced the point yesterday no help. on a cold morning start it wont fire up for like 10 min. when before it would start on the first try. It backfires on the freeway through the carb sometimes. Ive had flames out the carb several times when trying to start. It bogs no matter what i do to the fuel and idle screws at w.o.t. And this morning when it turned on there was oil it spat out the exhaust to the floor.

Tommorow im going to redo timing check valves and to a compression test.

If my l16 is no good im going to buy a complete Z20 swap.


So my question is what all has to be done for it to go in im dropping in the Z20 with its 5 speed all together.

Will i need my oil pan and pickup tube?

Shortened driveline?

Custom mounts?

Please if you know of other threads that i could not find please share or if you have info i would realy appreciate it.

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doesnt sound like your l16 is dead from what i just read it sounds like your timing is off and your not charging the battery 2 common issues especially if you still have a points dizzy have you done a compression test on it? oil in the exhaust is a little odd but that could be just blow by 


if your gonna do the z20 you will need to do alot different drive lines make an oilpan and pickup tube (z series leans the oposite direction of an l series and pans are model specific should be able to use stock z series mounts though 

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Really battery? How much can timing change my mpg's? I used to get 31mpg now im at less than 15mpg. Well when its idling and i turn on my light rpm's drop. Then i turn on my hazards drops more. Then i turn on my heater blower and it will lower more and die. I did a battery relocation to the bed but never had issues.


Im going to do a compression test tommorow.

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Dont get me wrong this motor is prolly tired. It came in my truck. it was siezed. I got it to turn over after drenching it in marvins mystery oil for two weeks. Ive driven it 13,000+ miles since i got it. Hard and easy on it been through 2 starters 2 alts 2 diffs 2 carbs and who knows what not. I think this ol girl is just tired.

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if is still got points in it the timing will change as the points wear out the dwell changes which changes the timing and if the battery isnt charging it will cut out im experiencing the exact thing right now the system charges when the lights are off but once there on the amperage drops to a point that it no longer charges the battery 

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A few things:


1) Dying because the headlights are on is likely a charging or wiring issue. I'm surprised it still starts at all, because it sounds like it's not charging, hence not enough voltage to keep the coil at the proper voltage for good ignition (which would explain the poor mileage). But if it always cranks (even when it won't start) it's possible the coil is failing or you have a wiring problem to the ignition, or the ballast resistor is nearly burned out. The backfiring and flames out the carb are both signs that the ignition is cutting out or not getting enough voltage to charge the coil.


2) The carb mix and idle speed screws do NOTHING except at idle. There are no adjustment screws on the carb that are supposed to affect operation above idle, but turning them out too far (for example making idle too rich) will kill the mileage but give no help off idle.

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Best sort out the L16 as best you can... that's the cheapes easiest route. 15 MPG is choke stuck on, carb flooding or really bad timing. All fixable. A compression test might show really good and so the motor is in good shape just needs things adjusted. It might  show a bad head gasket... again fixable and cheaper, easier than a motor swap.




For a Z20 swap you will need a 720 truck oil pan and pick up tube at least if this Z20 is from a car.


The Z20 5 speed is likely longer than the 4 speed behind your 521 motor so the driveshaft will need shrtening and the tranny mount modified.


Z20 carb is on the right side so a longer throttle cable is needed.


Z20 exhaust pipe is different than your L16 so something will have to be made up in order to connect to your system.


Z20 engine mounts. Dual coils.

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I also forgot to mention there are times that i wil be at a light and it dies and to start it back up i have to floor it and it starts to slowly climb the rpms bogging its way up ill push it as high as i can then let off then it wont happen again


also sometimes when i see its guna die i try to save it by pressin the gas like crazy. When its about to shut off and i save it and the rpms are low enough i hear some kind of knocking but only in these conditions.

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Check the valve lash 0.008 intake and 0.010 exhaust on a warm engine. I fear the valves are fucked, maybe even burnt and would explain the carb back firing.


You could remove the head and if the pistons do not have holes in them, maybe just throw another L16 head on and see...

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A tight valve will not let it close properly.


A tight exhaust valve needs to cool down by resting against the cooler seat. Exhaust seeping past it will burn a hole in it and the seat.


A tight intake will leak intake vacuum making tuning very difficult. A leaking intake valve can also let the firing cylinder explode into the intake and out through the carb.

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So i readjusted the valves just earlier. She is back in action the rocker arms i think are no bueno in cylinders 3 and 4 but it runs waaaay beter no more sputering or hissing from the carb. Idles way beter too. Going to switch out the head this weekend with another 210 with some aftermarket goodies inside it. Thanks for all the advice and help from my friend carlos and jesse (zeusimo)


who woulda know all my truck need was some head haha.

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