Anybody know if the 260 and 280 cranks are interchangable? Same part number?
Thanks

 

Can we expand this question to also include the 240Z and 280ZX please?

 

The 240 and 280 cranks are different. The 240 used a 2.9 stroke, and the 280 a 3.11. However, both the main and rod journals are the same size for the 240's - up to at least the 78 280 Z motor.

Sorry, I do not have an spec's on the later ZX motor, but if the late ZX blocks had siamese cylinder spacing, and I believe the late ZX cranks would have a different spacing for the main and rod journals on the late ZX crank, much different from the early 240 - 280 Z motors.

Hope this Helps!

Enjoy the Ride!

Speed

 

It looks like the eary 260 and 280 Z cranks share the same stroke (3.11) and have the same diameter main and rod bearing journal sizes.

The difference between the two is the bore of the cylinders, the 260 standard bore is 3.27, and the 280 standard bore is 3.39.

The 260 rods are 5.1319 between centers of the piston pins and the crank journal. I can't find a listing for the 280 rods, but if they share the same stroke (3.11) and have the same cylinder block height (which I am uncertain of) the 260 and 280 motors may have used the same rod length. You need to check this out further!

Speed

Enjoy the Ride!

 

That's great info, thanks. A friend (teds280z) tore up his crank and I will give him the one out of my 260 parts car. I have heard that the 260 rods are used in the 3.1 stroker motors so they must be a different length than the 280s.

 

For what it's worth, the Lengine software seems to believe the following specs:
L24 rods, 133.0 length
L26 rods, 130.3
L28 rods, 130.3
"L31", 3.1 liter stroker build, use L24 rods, 133.0 length
It also seems to indicate that the ZX motors used the same L28 crank, but their were three different pistons used (for Z vs. ZX turbo vs. ZX NA), and of course the different heads. Other than the siamesing between the cylinders, I believe the L28 blocks were the same across the 280 part of the S30 series.
Hope the crank swap goes smoothly,
Dave

 

Thanks for helping with this. Finding just a crank is hard unless you go to a wrecking yard and I've been told I had to get the motor. Probably BS.

 

What crank ar eyou looking for? I have a couple for sale.

 

Well, Ted came over today and we pulled the 260 engine. Much to our surprise, the crank is so nice it will only require a light polish if anything. So he's got a crank and I got the 9mm stroker crank rods!

 

Sweet. :d Now you can start your build.

 

I bumped into a guy today that just happened to be a parts counter man at the Datsun dealer in Las Vagas in the 70's. He told me that the Siamese cyclinder design means that there isn't any water passager between the pairs of the cylinders. This made a much stronger block. The stroke was the same from 74' through 83' (3.11 inches) and the cranks are interchangable 70'-83'

 

I checked the 260 rods and they are 130.3mm. Zhome .com shows stroker combinations with the 240 rods and the 260/280 rods. Depends on the pistons whether you want turbo or na.

 

You guys ever see the "handy dandy denny reference". Lots of info.

http://www.kaynor.net/v8-240z/240z.htm

 

i'M GOINGTO DROP THE MOTOR OFF TOMORROW AT THE MACHINE SHOP. i'LL BE FINDING OUT REAL SOON IF REBUILD IS OK. $1350.00 HERE IN RENO,NV.

 

Well Ted, you've ridden in my car, you better be able to beat me now!

 

The cranks from the L26 in the 260Z through the L28 in the 280ZX (all ZXs use the same crank) are the same and interchangable. Just to clear things up.

 

Yeah, your right. I also found that the 260 rods are the same as the 280s, RATS!
I was looking at the torque specs for the rods and the '73 is more than the 70' - 72' which suggests that the 73's might be the only ones with 9mm rod bolts.

 

That is correct.

 

Hey Tom, you know I'll beat you I've got a polished valve cover now. Less air resistance but can't race until I replace all the bushings in the suspension.

 

Oh yeah? Well I got polished SUs and I will have Budda polish my valve cover too! Then what are you going to do? Hey, let's go to Pick and Pull this Sat! I'll bring my truck and we'll load that madre up!

 

I'm also polishing the front cover and other parts. The engine will be really fast because it'll feel good about itself. I am out of transportation until I get my Z done. The kids are moving out, finally.