how to build a LZ24 engine

[Rat720]

Ok guys, I have searched and searched and cannot find a straight write-up. I want to do this instead of completely swapping out my z24 (for now anyways). I know I need a l20b head but what all do I have to do mods wise to build this engine. Is it a fairly simple swap out of heads? I love the lowend torque and just want to better that.

Thanks a lot

[datzenmike]

First for this to work the engine needs L20B mounts to tilt it into position or the intake and carb will be on a slant down toward the steering column. The air filter is going to be an extremely tight fit against the master cylinder as it is. To counteract the tilt you will need an L series transmission or the front case from one swapped onto your NAPS Z transmission.

 

 

One round port W58 or square port U67 L20B head. Both use a 4 into 1 exhaust manifold. The single down pipe will have to welded to your pipe behind where the two join. Intake and exhaust manifolds. W58 and U67 intakes or exhaust manifolds can't be swapped. A Z24 head gasket with an old L series front part grafted on to seal around the timing cover.

 

One L20B truck oil pan and oil pick-up tube.

 

Both L20B motor mounts from block to the rubber mounts.

 

One L20B timing chain cover. NOTE: Because the Z24 is 20mm taler than the L20B there will be a 3/4" gap between the top of the L20B timing cover and the underside of the L head. This gap needs to be sealed. A second L20B or maybe any other L cover could be trimmed and welded on to raise the height.

 

All the valve chain components forward of the block. This would be guides, tensioner, chain, pulley, woodruf keys, oil slinger,crank sprocket, oil pump/dizzy drive gear and spindle and distributor. You can use either oil pump. Use your water pump as it's a higher volume unit and the fan from it won't fit an L20B pump anyway. NOTE: I've had lots of Z and L series apart and lots of this stuff looks the same. If you feel adventurous try using your stuff and only change the chain. CHAIN: The L20B chain needs to be increased in length four links (use the old Z24 chain for this) by using Mercedes master links Part # 000997-0598 to match the Z24s 3/4" extra height.

 

The Z24 dip stick will now be covered by the L series intake/exhaust manifolds and difficult to get at. The easiest thing is to check the oil when motor is cold. Or retro fit a longer tube and flexible dip stick from another motor that clears this obstacle. Fill with 4 liters and calibrate the new stick..

 

 

Probably overlooked a few things that can be added later.

[hang_510]

havent seen any comprehensive writeups.

 

 

i had no issues w/dual carbs and the stock loacated dipstick

 

 

 

 

i have ALL the necessary timing components, most i have 2 of.

 

actually, i have everything except, a block... :(

[Rat720]

Sell.......to me?? :-)

[hang_510]

One L20B timing chain cover. NOTE: Because the Z24 is 20mm taler than the L20B there will be a 3/4" gap between the top of the L20B timing cover and the underside of the L head. This gap needs to be sealed.

yeah! Z24 cover, got 2 of these, 1 needs the 2 holes for the head tapped.

then you can use the Z24 (carbon)head gasket.

[hang_510]

Sell.......to me?? :-)

:thumbup:

 

id like to sell everything ;)

 

doubt ill build another, since i already have 2 bad blocks :angry:

[Rat720]

Hang510....how much? So with all you have I can build the lz24 with the running z24 that's in my truck now? You have head and all??

 

How much?

[sinner720st]

im rocking the z24 right now... i was just wondering what the main reasons are for the head swap... i think i have read datzen mike and maybe a couple others that the heads flow about the same but you can get a bigger cam in the L head, due to virtical valves... is there something im not getting. i just dont see the point,

 

not that im saying its a bad idea i just have not been taught yet. and i think some good info would be good for the thread

[datzenmike]

They both flow about the same up to 4-5 K

 

The Z motor drops off pretty quick after that while the L series can continue on for about another K.

 

If you are going to make more power you have to rev the motor higher. All things equal a motor will double its hp when you double the RPMs. The limiting thing is getting enough fuel and air into it. Call this 'breathing' and it is almost totally influenced by head design. The L head has more potential for good breathing at higher RPMs than the Z head.

[hang_510]

So with all you have I can build the lz24 with the running z24 that's in my truck now? You have head and all??

yup!

 

U67 w/a .510 cam (just got a call from the machinist thats its ready for pick up)

ill reassemble before shipping.

 

2 chains and timing covers; 1 needs to be tapped.

will include the sprockets. youll need new guides and tensioner.

 

2 cranks; 2 set of rods(1 w/stock pistons)

 

 

complete 40phh mikuni set up (may be too small for this, i was running 45's and put em on my LZ22)

 

 

theres more... PM for a better list and $$$$$$$$$$$$$$$$$$$$

 

 

 

if a free Z24 block majickly appeared, id be build it for myself :)

 

i took the old >7000 :ph34r:

[banzai510(hainz)]

how to build a LZ24 engine ????????

 

Have somebody else build it. use it then when he swapped for a KA you pay him half what he paid to build it.

[hang_510]

Have somebody else build it. use it then when he swapped for a KA you pay him half what he paid to build it.

:rofl:

im not gonna build it for him, i dont have a block

 

 

selling the carbs to buy a KAde topend, or... :hmm:

[datsunfish]

Datzenmike,why do you say you cant use the old style exh and int manis? I am building this motor but dont plan to use either but I am just curious as to why not./? I will be using an edelbrock intake and a header. And as far as the chain,I have ordered the 2 mercedes master links but they say you need 4 extra links. Is that 4 including the 2 mercedes masters for 4 total or 4 between them, and is that 4 more than the l20b chain? Mine will go in my 521 and the oil pan already had to be hammered a bit to clear the crank. I assume I will need to bang it some more for the even more than l20b stroke. Is that a good assumption??

I want to do this because I love L series motors. I dont care for retrofit shit in my old school rides. I want to open the hood and see period correct stuff but I want it to be peppier than the same ole L16,18,20bs I have had for years... I am the guy who would spend tons of cash to hot rod something old for the cool factor. I will always admit that every car out there is faster than mine but if we could take it back in time,look out!!!

[datsunfish]

how to build a LZ24 engine ????????

 

Have somebody else build it. use it then when he swapped for a KA you pay him half what he paid to build it.

I plan to build mine on the cheapo and smoke some tires so you dont see the exhaust smoke!!!!!

naps 24 said to be a runner with all the z tbi stuff and junk $175.tore it open=horrible ridge,pitting and trashed pistons... priceless 175 in the toilet

naps said to be a good runner...$49 tore it open,scoring and a tore up piston...stack of good pistons,honed out nice,L stuff clogging my toilet=priceless

I feel the need to do it because I may have a shot this time...

[datzenmike]

Datzenmike,why do you say you cant use the old style exh and int manis? I am building this motor but dont plan to use either but I am just curious as to why not./? I will be using an edelbrock intake and a header.

 

I don't think I even mentioned the old style ones.

 

W58 and U67 intakes or exhaust manifolds can't be swapped.

 

What I meant here is that the U67 intake and exhaust manifolds are bolted together and have to be swapped to any other head as a set. Also worth noting is the W58 head has round exhaust ports. Round ports can be run into a square manifold but not the other way around.

 

 

And as far as the chain,I have ordered the 2 mercedes master links but they say you need 4 extra links. Is that 4 including the 2 mercedes masters for 4 total or 4 between them, and is that 4 more than the l20b chain?

 

 

The Z24 is 2 cm taller so you will need 2 cm of extra chain on both sides of the cam sprocket. Or 4cm / 1.576" of extra chain total. Jason Grey recommends: ....lengthen the L20B timing chain by adding 4 extra links of datsun chain using 2 master links from a Mercedes-Benz timing chain (#000997-0598)

 

 

Mine will go in my 521 and the oil pan already had to be hammered a bit to clear the crank. I assume I will need to bang it some more for the even more than l20b stroke. Is that a good assumption??

I want to do this because I love L series motors. I dont care for retrofit shit in my old school rides. I want to open the hood and see period correct stuff but I want it to be peppier than the same ole L16,18,20bs I have had for years... I am the guy who would spend tons of cash to hot rod something old for the cool factor. I will always admit that every car out there is faster than mine but if we could take it back in time,look out!!!

 

Back in the late '70s I shoved an L20B into my 521 to replace the L16 motor. Man I didn't know shit about Datsuns. By shear dumb luck it was a car motor and had a 200mm clutch to match the 521's. The car pan wouldn't have fit a truck so I would have had to use the L16 pan on it. I did not have to hammer the pan.... I do remember that!

[sinner720st]

Posted 27 July 2010 - 06:03 PMThey both flow about the same up to 4-5 K

 

The Z motor drops off pretty quick after that while the L series can continue on for about another K.

 

If you are going to make more power you have to rev the motor higher. All things equal a motor will double its hp when you double the RPMs. The limiting thing is getting enough fuel and air into it. Call this 'breathing' and it is almost totally influenced by head design. The L head has more potential for good breathing at higher RPMs than the Z head.

 

 

the whole crossflow design with the exhause velocity helping pull air n fuel in on the z head doesnt make it flow better than the L head??

 

just how much of a gain are we talkin about here???

 

im runnin the napsz with a dynoed 110hp (ign timing set @ 8*btdc, stupid) prob closer to 120hp w/ign@ 14*btdc... it pulls pretty well from 2k to oh about 4,500 then not so much so if the L head is good to 6k then it would have then potential to create more power from the motor

 

 

another question is.... what is the good thing about the z block? does it have a longer stroke and bore (it should if its the z24) thanks for the info

[Z-train]

Medium block 2.4 Liter.

Stuff a Z24 crank and pistons into NAPS-Z or L20B block bored to 89mm by cutting down crank counterweights and clearance grinding block as per Ben Pila. This gives you a 2389cc L-series motor that doesnt require using defective (crack prone) Z24 block, fabricating timing cover, lengthening timing chain or modification to close hood. Z24 piston tops will need to be milled down slightly. Fedral-Mogul 33.8mm pin height pistons might not need milling? Click HERE for Bens write-up of necessary modifications.

Compression ratio with Z24 pistons and open chambered head is 10.25:1 before pistons milled.

parts: : modified Z22 block, modified Z24 crank, modified Z24 pistons, Z22S/ L20B rods

s/2+r+p: 227.7

piston deck height: 0.45 (above deck)

[datzenmike]

the whole crossflow design with the exhause velocity helping pull air n fuel in on the z head doesnt make it flow better than the L head??

 

just how much of a gain are we talkin about here???

 

 

I've never understood the term 'cross flow" I know what it is, but a properly designed wedge head will work as well and if tuned properly will use exhaust flow to 'pull in' intake air. Any motor can be made to do this.

 

To make power the head is everything. You want to get as much air in and out as FAST as possible.

 

To breath well, the intake and exhaust ports must be as straight as possible, (well along with other things*) but ports should have minimal bends and restrictions in them. As air flow speed increases, so does it's inertia. Think of a line of cars going 60 around a 20 MPH corner while inside a tunnel. The air will not be able to make a sharp turn and 'rub' against the outside of the port wall slowing it and causing a back up behind it. Even worse is the inside of a turn, here the air separates from the wall and becomes turbulent. Think of sucking pop through a straw... it gets harder and harder the faster you try. The straw diameter and any bends put a limit on how fast you can draw through it.

 

The L head has the intake ports well above the exhaust ports (on the same side) and they are well above the block surface. This allows a more downward direction for the ports and a minor bend at the valve stem before entering the combustion chamber. This is critical for intakes as they operate at atmospheric pressure (about 15 lbs) while exhaust gasses are under extreme pressure (hundreds if not thousands of pounds) and will have little problem getting out.

 

 

The Z head, on the other hand, has intake ports much closer to the block surface with horizontal runners with a sudden sharp bend at the valve stem and into the combustion chamber. At low speeds they will flow just fine and probably at least equal to each other, but if pushed, the Z engine will struggle to draw in air at RPMs where the L has no problems.

 

im runnin the napsz with a dynoed 110hp (ign timing set @ 8*btdc, stupid) prob closer to 120hp w/ign@ 14*btdc... it pulls pretty well from 2k to oh about 4,500 then not so much so if the L head is good to 6k then it would have then potential to create more power from the motor

 

This sounds very much like a Z motor. It was never intended to really exceed normal driving RPMs like on the highway. Partly to keep it within a range where pollution controls would work and not add to it. 8 degrees advance is likely correct for the motor you have. Do not confuse single plug L motors with the dual plug Z engines as far as advance is concerned. Because the mixture does not burn instantly, all gas engines need to start the ignition of the fuel and air slightly before top dead center so that the hot expanding gasses reach their peak pressure at about 17 degrees after TDC to exert maximum thrust on the piston. If you think about it, lighting a candle at both ends will shorten the burn time. The same happens with the dual plug Z head. Dual plugs will allow LESS advance because there is a shorter burn time. With a shorter burn time you can light it later in order to hit the 'sweet spot' at 17 degrees after TDC.

 

 

another question is.... what is the good thing about the z block? does it have a longer stroke and bore (it should if its the z24) thanks for the info

 

The Z block is basically an L block that is taller by 2cm and has a larger 89mm bore and stroke. Larger bore and stroke will equal more torque.It should be noted her that the Z24 block is alleged to have inferior metal in it and is crack prone. This could also be simply that the Z24 has fewer threads for the head bolts to hold onto. The Z24 is also prone to blowing h/gs but this is preventable by re-torquing the bolts at every tune up. (not done on other Z or L motors.

 

* Other things needed are stiffer valve springs that prevent valve float. The Z is alleged to have weak springs when they are used or old. This will limit revs and revs make hp.

 

Valve size. Larger valves let in more air. Unfortunately the Z series valves will touch each other if too large a valve is used.

[67 411]

So putting the z crank and pistons in a l series is kinda like making a stroker? I was also wondering if I could do this to my L16 block, instead of finding a L20b?

[MicroMachinery]

The L20b has a taller block, so the crank throws can clear with some grinding of material. I don't believe w/ an L16 that you'd be able to make it work. There's a different way to stroke an L16.

[67 411]

How is that done?

[datzenmike]

So putting the z crank and pistons in a l series is kinda like making a stroker? I was also wondering if I could do this to my L16 block, instead of finding a L20b?

 

 

The Z24 crank won't fit the L20B block. With a LOT of work it can be made to fit but why? The Z22 crank will fit but why not just use the Z22 crank in the Z22 block?

 

The L16/18 is a 5 bolt crank. No 6 bolt (L20B, Z20, Z22 or Z24) crank will fit. The main bearings are totally different.

[CableDroid]

Digging up an old thread...

 

Considering doing a Z24 short block with my W58 headed L20B in my 4 speed Goon (Weber DGV).

 

First for this to work the engine needs L20B mounts to tilt it into position or the intake and carb will be on a slant down toward the steering column. The air filter is going to be an extremely tight fit against the master cylinder as it is. To counteract the tilt you will need an L series transmission or the front case from one swapped onto your NAPS Z transmission. One L20B truck oil pan and oil pick-up tube. Both L20B motor mounts from block to the rubber mounts.

 

So using the L20b mounts puts the Z24 block in the same position as the L20b originally sits now? Not sure if my L20b has a car or truck pan, how can I tell?

 

Since I already have a L20b, I figure I am half way there using my L20b head on the Z24.

 

I can score a Z24 and 5 speed from mid '80's 2wd truck for $300. Can I use my 4 speed front case on the Z24 5 speed to make it work in my Goon?

 

Thanks!

[datzenmike]

If the L20B is from the car you want to put the Z24 block in you're good. The truck oil pan is deep to the rear. A car oil pan is deeper in the middle with room for the steering to pass behind it and the cross member in front. Just because it's a car oil pan does not mean it ill fit. there were variances.  A truck oil pan definitely won't fit.

 

You need everything off the L20B except the block, rods/pistons and crank. The Z24 block is 2cm taller so the front of the timing 

cover has a 2cm gap that needs closing. The timing chain will need lengthening by 4cm.

 

If your four speed has a removable metal oil pan then no.

[CableDroid]

If the L20B is from the car you want to put the Z24 block in you're good. The truck oil pan is deep to the rear. A car oil pan is deeper in the middle with room for the steering to pass behind it and the cross member in front. Just because it's a car oil pan does not mean it ill fit. there were variances.  A truck oil pan definitely won't fit.

 

You need everything off the L20B except the block, rods/pistons and crank. The Z24 block is 2cm taller so the front of the timing 

cover has a 2cm gap that needs closing. The timing chain will need lengthening by 4cm.

 

If your four speed has a removable metal oil pan then no.

 

I guess I am confused to why you mentioned one would need a L20b truck oil pan if it won't fit. I assume that if my current oil pan fits on my L20b in the car now, continue to use it on the Z24 block.

 

My current 4 speed has a metal pan with a drain plug. So I guess that is a no go. What year/make/model do I need to look for a donor front case to work on the Z24 truck 5 speed? Thanks!!