screw it im gonna do an LZ24

[datsunfish]

While cleaning up my property recently I decided not to chuck one of the so so naps 24 blocks I have. One of the cylinders was pretty scratched up but suprisingly with some honing it actually disappeared. Tore it all apart and it seems like it should be good enough to work. I already welded up the head mounting points on the front cover all I got to do is tap em out. I ordered some gaskets and the mercedes master links. This will be going in my 521. I have done a couple succesful datsun motor garage rebuilds so I figure why not see how it goes with the hybrid. Not lookin for a racer,just a tough truck motor.

The only thing is that one of the pistons is a little banged up. What would be the drawback to using a different piston? I dont think it would be that bad if I did. It seems to fit fine but I know its not recommended. Just wanted to share what im up to since I dont frequent the site much anymore.

[WAGON JON]

Nothing is wrong with using a new piston. It won't hurt anything. It is probably a good idea because the previous piston could have a hair-line crack in it. Could cause problems down the road. :angry: My friend Daryn build a naps z24 with an l-series head which worked awesome. It had lots of torque. The factory head works great too. I have another friend that got his truck up to 130 mph with a factory z24. Strong engine and had no problems.

[hang_510]

i liked the LZ24, if i had access to another block id build it better than before :w00t:

 

 

i have a stock bore piston you can have for shipping (actually 2 are still good)

 

 

 

 

DANGER-DANGER

[datsunfish]

Any opinions on how to build a head for this motor? I have a U67 I plan to use but not sure if I should put in larger valves and do some minor port work. Would I benefit more with larger intake or larger exh valves? What would be a good cam lift? It would be nice to keep the stock springs so would 460 be good enough? Or should I go full out and spring it up for a 480 cam? Im only planning to use a weber dges 38/38 downdraft on my edelbrock manifold so not looking to rev too high,I just want the most power and smoothest ride possible within reason.

[datzenmike]

The piston has to fit the bore and have a clearance of 1 to 2 thousandths of an inch around it. Measure the bore a couple of inches down and then the piston diameter. The difference is the clearance. Since this is a used motor the clearances will be more than when it was assembled but may still be within tolerances. The Z24 piston to wall clearance is 0.001 to 0.0018". A standard Nissan Z24 piston is never exactly 89mm. Because of mass production it will fall between 88.965mm and 89.015mm or a difference of about 2 thousandths of an inch. The block bore is also not exactly 89mm from the factory but falls within a 2 thousandths range above this for proper clearance. When assembled, a slightly above bore is mated with a slightly over size piston to keep the proper side clearance.

 

Yours is likely fine but you should check this. A 'loose' piston in a worn bore may not seal properly. The rings will extend out from the lands further and the end gap will be wider and leak compression.

 

 

The U67 is a very good choice. It breaths just fine as is and will work way better than the Z head above 4K. A cam is the quickest and easiest way to improve the breathing without the expense of oversize valves. Again most of this breathing improvement will be well above 4K where you don't drive much and won't really show up at low speeds. The stock springs are fine for under 6K. I would run a stock head and drive it. Keep my eyes open for another and maybe do it up and swap on later to try it.

[datsunfish]

My best bet is probably the u67 I have then but its completely disassembled. A valve grind is pretty cheap so ill make it work. Not a true shop built block so why go all out on the head. Just looking for low end power anyways. 6k is all I need.

[hang_510]

so why go all out on the head. Just looking for low end power anyways. 6k is all I need.

a regrind cam ~.480 w/o needing bigger valves would be a good match in the U67!!!

 

i used that head/cam w/all the head work... it IS fun! :w00t:

 

did i tell you i have the timing componets avail???

[datsunfish]

Just installed the pistons into the block,just gotta torque the rod cap nuts and shes ready to put together. Still gotta build a head and tap out the timing cover welds but the major work is over.

Was thinking about using a w58 head since I have a round port header,only problem is that my only w58 is a peanut chamber. Would a head shim bring the comp down enough? Or if I did a major unshrouding since the bore is so wide??

[datsunfish]