Different sizes of caps and rotors?

[matrophy]

Bought cap and rotor from RockAuto for '86 720 with z24 and the rotor is too tall and doesn't lineup with screw hole in dist shaft by about 1/2". I assume that the cap that came with it wouldn't work with a shorter rotor. Are there 2 sizes of caps and rotors possible for these trucks? My wiring harness matches 1984 exactly so I'm wondering if my distributor is from an earlier year as well.

[Charlie69]

When I buy a cap and rotor now days I order the cap and rotor kit so ia ma sure the cap and rotor match.  I quit buying from Rock Auto for this reason I would get the correct part # box but the part in the box was wrong.

[matrophy]

I did order the kit. There are no markings on the parts so I can't tell if the wrong part is in there. In your experience are there 2 sizes of these caps/rotors for 720s? Where do you buy yours from? I am not married to RockAuto for sure although now I have a store credit...

[Charlie69]

I buy most of my parts from NAPA.  I could not say if there are 2 heights or not. I have worked with  Z20 and Z24 engines in the later 720s.  I have also had at least 10 or 12 1980 720s with the L20B engines.  I have purchased an 81, 82, and 83 but none of the had engines when I got them.  My 84 and 85 720 2wd king cab STs both had Z24s in them.

[matrophy]

Thanks. I am ordering a set from NAPA. I'm assuming that RockAuto put the wrong thing in the box or whatever

[matrophy]

Here's some info I got from a Facebook poster who works at a Nissan dealer (so I'm not crazy):

There are THREE 720 distributor caps

1)

1980    L20B

2)

1981    Z22

3)

1982-1983.0    Z22

1983.5-1986    Z20, Z24, & Z24i

There are FOUR 720 rotors

1)

1980-720

2)

1981    Z22

3)

1982-1983.0    Z22

1983.5-1986    Z20, Z24

4)

1985.5-1986    Z24i

[Charlie69]

On 5/24/2020 at 9:09 PM, matrophy said:

Thanks. I am ordering a set from NAPA. I'm assuming that RockAuto put the wrong thing in the box or whatever

Rock Auto sells old stock from various automotive warehouses,  Chances are that Rock Auto did not do it, it was probably mixed up somewhere in the 30 to 40 years the parts have been transfered from one warehouse to the auto parts store and back again. 

[MaddieCycle]

I had this problem too with the rotor/distributor on my '86 KC with a Z24, the truck was manufactured in June 1985.  I also had a problem with the air filter not fitting properly.  I got all of this stuff at O'Reilly.  I forget how but I figured out that I needed to order for '85 model and when I got those parts they all fit perfectly.

[Charlie69]

It is I believe the difference in carbureted and throttle body.  Also the Z20 takes a different cap and rotor on some models.