Like clockwork, the head gasket goes at 220,000k for the 2.4 (Z24). ALL THREE OF MINE WENT. I'm a bloody expert on doing the heads on Nissan Z motors. My dad's and my brother's 1981's with the 2.2 (Z22) never went even with 320,000k. 2.2 has more meat between the cylinders and more gasket.
When the gasket went, it spalled the rings in number 4 cyl and cracked the head - in only 5 miles. Fortunately I've had 4 720's and an engine I scrapped had good pistons. I put the number 4 with matched crank bearings in and honed the cylinder. I had an odd-ball 2.2l head I picked up in the wreckers a few years ago for a spare that only has 4 plugs and a knock-out for the manual fuel pump. The valves are a couple mms smaller and the combustion chamber is too, but the result is phenomenal! It's better.
I've got over 180lbs compression in every cylinder, I can burn-off the tires in first, and she'll let out a big squawk in second and third gear!
The only problem I really have is the passenger side e-brake cables; they're always seizing up and need to be replaced every couple years.
I've had 4! Love them! Gave one to my dad when the motor was shot, and he put the 2.2l in it when he scrapped his 81, because the body was gone. My brother also had an 81; we still have it for parts, perfect motor.
Scrapped one, kept the other blue truck, drove it for years, and finally parked it for parts for my 1985.
When I first got the 85, I got 38mpg (can) with 2 adults and a teen in the vehicle. I put a roll-bar and bush-guard, spoked mags, hood scoop, louvres and painted it bright orange with rally stripes. Kid's actually stop playing and run up to the side of the road, and wave and cheer! They never seen anything like it. High-school girls wave!
I'm gonna paint it British Racing Green this time to go with the beige interior.
I've outrun Tiburons with over 1/2 ton in the box; I didn't know he was trying to pass me till I let-off the gas!