Are all crankshaft pulleys physically interchangable on all L6 cranks (240Z to 280ZX)? I need a 3 pulley arrangement to replace the 2 pulley on my 11/70 240Z 2.4 L6. I have a 3 pulley from a 280Z (possibly ZX) and don't want to jump into a pulley swap unless I know it will go okay.

I know the 240 and the 280 have different timing marks and indicator plates. You need to change the front cover to match the harmonic balancer. I am not really certain about the 2-ramp vs. 3-ramp pulley. I am guessing they are the same.

I hadn't considered the timing marks but that's easily resolved. The front cover is another issue all togather. Is that because of the seal surface diameter, timing marks or what? Is the crankshaft snout the same diameter on all L6's?

Choice of fan is important also. If you use the 3 row pulley from a ZX you have to use the fan from a ZX also otherwise the fan will hit that 3 row pulley. I know this from personal experience. Beware that a ZX fan will sit closer to your radiator. There's more space between the fan clutch and radiator in a ZX.

Was there ever a third pulley option on the 240Z pulley (has two bolts in front and smaller overall diameter)? If so, does anyone have such a piece lying around and gathering dust? I'd like to acquire it.

240 with dealer option air had 3 pulleys IIRC. The last pulley bolted onto the front of the normal pulley I think. It's been at least a decade since I saw one, so I could be remembering wrong.

No you are right jmortensen, and I think I still might have mine laying around somewhere. If anyone is interested in it PM me and I'll go looking for it.

The timing covers will interchange without any problems related to the seal on any S30 Z car L6 engine.

The various timing markers attach to the timing cover by means of small bolts. The dampner/pulley and timing markers MUST be compatible.

Best bet is to get a dampner/pulley AND the timing markers from the same engine to be installed on your engine as a complete set.

For 240Z's there was a "Euro" dampner available at one time. Don't know if it still is available or not. Also don't know how it differed from the "normal" dampner for the North American market.

The Euro is smaller and lighter and has one pulley (no smog pumps in Europe)

That is what I have on my ZX Turbo block... an Euopean single ramp balancer. I had to change the the timing marks to get it to work. I used an older 240Z front cover. I like "kiss" when it comes to engines. "keep it simple stupid"

all crankshaft pulleys physically interchangable on all L6 cranks (240Z to 280ZX)

YES all nissan L engine internal balance