engine swapping from 720 to 720

[twitcharris]

im elbow deep in this engine swap, you see,

i just got my grandfathers 81 720 reg cab with a non-running z22 under the hood

and i have my fathers 84 720 kingcab z24 that has carburator issues and is smog choked, so im restoring my grandfathers truck and swapping engines.

i currently have the z24 completely apart and am waiting for an engine rebuild kit. heres a shot of the 84:

and the 81 is a light blue regular cab truck. faded to white haha. no pix yet. gunna drop it and put the rims off my 84 on it

[datzenmike]

The '84 motor is 2cm taller so to be safe use the '84 motor to motor mount brackets.Too bad you are in California and it's equipped with the ECC Electronically Controlled Carburetor. It's notorious for the wires breaking internally at the plug at the back of the carb. These wires control the electric air fuel ratio solenoid, idle cut, choke heater and a throttle position switch. If the wire to air ratio solenoid breaks you get a default rich 'limp home' condition. If the idle cut it won't idle. If the choke heater the choke won't shut off when warmed up, If the throttle position switch the ECU thinks you are not at idle when you are.

 

If you can get it running try wiggling the wires at the connector. If the engine idle changes expect a bad connection. At the least unplug and confirm the wires are not broken inside the insulation.

 

There is also a water temp sensor to tell the ECU that the motor is warmed up and to start adjusting the mixture for best economy. This changes the O2 sensor from open to closed loop operation to start monitoring the air fuel ratio.

[twitcharris]

I plan on using the carb from the 81, but imma use the z24 with the older carb.

[datzenmike]

Won't fit the Z24 intake.... you'll have to swap the intake too. The bolts line up but the port shape is different so clean well and use a good gasket. Do-able.

[twitcharris]

Cool! Thank you for your help! Would I get more power from the z24 carb or the z22?