which engine to build

[laotsu]

I really wanna put an LZ in my truck. Right now I can get my hands on a  Z22. It is in a JY 720 that has been sitting so long the carburetor is full of rat shit and the bottom end is caked with mud like it was in a flood or something. Or I can get a  Z24 that looks pretty clean. I know getting a timing cover for the LZ24 is a more involved fabrication than the straight swap nature of the LZ22 cover. I wonder if it is less work to refurbish the poor rat assed Z22 or to fab a timing cover for the Z24.

 

Maybe somebody has a Lz sitting around that they wanna sell?

 

I know most people will just say "why not go for a KA swap?" I guess I just like the idea of having a larger L series in Ol' blue.

 

thanks for your time

[Sealik]

Guess that depends on the condition of the Z22.

LZ24 will need 2 Mercedes master links to lengthen the chain....the Z24 TC cover 'will work' for the LZ24, other than modifying the L20B cover.....but.

Not perfect but I did get the Z22 cover to seal on my LZ23/U67 head....eventually I replaced it with the L cover when I located one.

I'll probably just shave the top of the Z24 TC cover next time and fix a thin plate to address the issues between the L head/Z TC cover....when I build a LZ24 that is

 

Z22 cover running Z24 dizzy on LZ23....no leaks

[laotsu]

so I think I will go with the Z24 bore it to 90.5 mm and put Wiseco KA pistons and a Z22 crank in it. Any objections to this idea? From what I can see this will be an almost perfectly square engine. Now to fund it!

[Dawa]

sealik, i always see people mention that the problem with z24 is the timing cover.. what exactly is the problem?

does it protrude too much or not enough?

[datzenmike]

The Z24 block is 2cm (3/4") taller than the Z20/22 or L20B.

 

 

 

so I think I will go with the Z24 bore it to 90.5 mm and put Wiseco KA pistons and a Z22 crank in it. Any objections to this idea? From what I can see this will be an almost perfectly square engine. Now to fund it!

 

KA piston, (90.5mm and assuming the same dish) Z24 block, Z22 crank with the 165mm  Z24 rod this makes a 2366cc motor with 9.39 compression.

[laotsu]

Mike what do you think of my "nearly square" engine plans? do you forsee any problems with boring the Z24 out to 90.5 I hear that the cylinders are pretty close together

[datzenmike]

90.5mm is 60 thou off the walls. About the thickness of a quarter. I really don't know. The Z24 deck is prone to cracking though I have never had a bad experience.

 

90.5mm X 92mm is pretty square.

[Dawa]

mike, im still too dumb to realize the problem with a z24 block and cover combo with a L4 series head?

[laotsu]

the Z24 timing cover is too tall for the U67 head by 2cm. so either the z cover gets shaved or you fab a tall L20b cover

[Dawa]

thanks!

if its that simple idk what all the fuss is about then!?

 

if one is rebuilding their engine and getting the block decked, theyre supposed to bring their to

bring their timing cover/have it installed so that itll be level with the decked block.

 

i dont see a machine shop really caring too much about taking off 2 extra cm,

or one manually/crudely shaving off the majority of that extra height and then having the machine shop

do the rest.

 

so thats it? shave/modify a tc and add 2 links to the timing chain? those are the biggest problems?

 

i think i read elsewhere that z24 'doesnt have its own fuel pump' so id have to go electric?

 

and use  z24 motor mounts, and 31.5" trans (check!)

[Sealik]

The Z24 is 2cm taller than the Z22/L20B............

The top of the L ... TC cover has a different bolt pattern/etc. than the Z22/Z24. 

 

As seen here...

4-10mm bolts...Z

 

2-10mm bolts...L

 

 

Sooo...if you want to use the L20B TC cover and L dizzy on the LZ24, you have to cut/extend/weld the cover up 2 CMs...which will now bolt up and seal correctly to the L...... U67 head and or. 

Or....you could cut the top off the Z24 TC cover....let's say 1/4" and add some aluminum plate to seal the variances between the L head and Z TC cover. 

This would enable the Z dizzy....good or bad...you decide

[laotsu]

any objections to a Z22 crank in a Z24?

[datzenmike]

It will work. The rods and pistons will now rise 2mm shorter from the deck with a Z22 crank. This dead space above the piston to the top of the cylinder accounts for an additional 16cc of combustion chamber but the bore increase and the KA's 2.8cc 'dish' more than compensates for this and the compression actually rises slightly.

 

The only drawback is using a Z24 block... known for blowing head gaskets. I've heard that the bolts don't go in as far, I've heard that the deck is thinner and I've heard that the metal in the casting is a poorer grade. Whatever.  Re-torque the head bolts once or twice a year when the motor is cold and you should be fine.

[Dawa]

. i was aware of the whole 'redrilling HG' to match up cooling ports but oooh different bolt pattern. thats a pretty big issue

[Sealik]

. i was aware of the whole 'redrilling HG' to match up cooling ports but oooh different bolt pattern. thats a pretty big issue

 

That was for the LZ22/LZ23.....not the LZ24

Block is different again...haven't found any info on HG mods

Here's the Z24..

 

With modified Felpro Z24 (LZ23) HG for comparison

[datzenmike]

.  but oooh different bolt pattern. thats a pretty big issue

 

The bolt pattern is the same for L16 through KA24E. There are different bolts and lengths. I said that I had heard that the Z24 didn't go deep enough into the block. Maybe what was meant was there were less threads used? 

[laotsu]

The bolt pattern is the same for L16 through KA24E. There are different bolts and lengths. I said that I had heard that the Z24 didn't go deep enough into the block. Maybe what was meant was there were less threads used? 

 

 

why not redrill and retap for the stronger head bolts?

[laotsu]

That was for the LZ22/LZ23.....not the LZ24

Block is different again...haven't found any info on HG mods

Here's the Z24..

 

With modified Felpro Z24 (LZ23) HG for comparison

 

 

MAN those cylinder walls are close together! I'm not sure there is room to take 3mm between 1and 2  or 3 and 4. Hmmm may have to regrind the crank to get a square LZ24,

[laotsu]

so my research led me to http://720world.com/forum/topics/26-z24-stroker?commentId=2016119%3AComment%3A26867 where I found a guy, Steve G that talks aboot boring a Z24 to 90.5.... HOLY SHIT THERE WAS DATZENMIKE AND SEALIK! So Mike and Sealik you guys have argued all of this three years ago. Did Steve G ever bore that Z24?