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L26 swap 720 advice


RasselFlassel13

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First, anything where you have to cut the body..... doesn't fit.  As the bore spacing on an L series engine is 95.2mm and you have two extra cylinders you have 7.5" of extra length. That's  50% more than the engine in it, not one, not two, but 7 1/2".

 

a/ Loose the rad? Genius! Other than the nightmare of plumbing and electric fans you are moving the weight forward over the front wheels which is never a good idea.

b/ move to the rear? Cut the firewall, loose the heater. Gear shifter is now almost 8" to the rear. You still have the extra weight.

 

Second,  why a boat anchor L26 when there are readily available 4 cylinder engines that make more power? While we are at it... the L26 came with a piss poor set of SU carbs. Nissan dealership mechanics hated them. There are well documented four cylinder swaps...all the problems figured out.  Lots of after market support. Lots of spare parts in the wrecking yards or still driving around. KA24E or KA24DE are EFI and about 150 hp AND will work with your 720 transmission. There are turbo kits for this too. All those D21 Hardbodys you see have this engine in them, very common.

 

Third, do you have a transmission for this? Because an L series engine won't bolt up to the '84 transmission. 

 

Fourth, (and this is the worst reason for this swap) "I have a free '74 260z engine, the car is totaled. It runs and everything!" Just because it's free, running and available is no reason to use it. It simply is a very poor choice.

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Just because you can doesn't always mean you should.

Your realistically better off with a KA24de.

If you want to do it just to see if you can, go for it.

but if your doing it just because you happen to have an L26 laying around thats really not the best reason for using it.

 

the work/reward ratio isnt that great.

 

If its just an old L26 with some SUs and a stock manifold or even a header your looking at making 100-120HP
If you have something fresh with some higher compression, cam, what have you... your looking closer to 140HP

but then a stock stock KA24de is rated at around 150HP

... and it fits much much better.

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it really depends on your skillset. you can put anything into anything, really, but some things will fit with less fabrication. have a look at the links bilzbobaggins posted above and you'll get an idea of the kind of work you'll need to be capable of to do an l26 swap. 

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Seems like it would be the easiest to buy a good head from someone and have them ship it to you.

The L26 is a very long engine, not many would attempt such a conversion, and the ones that do would likely be in another country where shipping would be stupid expensive, and there are no other engines to get parts off of in their country.

Is there a difference between the Z20, Z22 and Z24 heads?

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There are rebuilt heads all over ebay some with free shipping.  If you try to swap engines this truck will likely end up at the scrap yard.  There is probably a reason the motor and trans was only $80.

 

This is an idea of what you are talking about doing! 

http://community.ratsun.net/topic/64040-720zx-time-to-finish-it/

 

Do you have the time place tools money and the skills to take on a job of this skill level?

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The Z20 has the mechanical fuel pump opening also, I was just asking as I have 2 Z22 heads and 1 Z20 head out back, but no Z24 heads to compare them too.

 

Port shape is the only difference as far as I know. And z24 heads do not have the mechanical fuel pump opening machined out, whereas most the z22s do. Unsure about the 20s

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There are rebuilt heads all over ebay some with free shipping.  If you try to swap engines this truck will likely end up at the scrap yard.  There is probably a reason the motor and trans was only $80.

 

This is an idea of what you are talking about doing! 

http://community.ratsun.net/topic/64040-720zx-time-to-finish-it/

 

Do you have the time place tools money and the skills to take on a job of this skill level?

 

Charlie and I know about this conversion stuff, we have 520 projects that we have been working on for YEARS!!!! :lol:

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The Z20 has the mechanical fuel pump opening also, I was just asking as I have 2 Z22 heads and 1 Z20 head out back, but no Z24 heads to compare them too.

 

And I have a couple z24 and 1 z22, but I've never even touched a z20 :)

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The Z20S head from the 720 mileage option (casting number W04) should be avoided* but the A10 and S110 200sx Z20 head is identical to the Z22 heads from truck or later S110. Naturally a Z24 head will always be the best fit. All three (other than the Mileage Option) have the same combustion chamber size (I have two of each and have cc'd them) so the compression will be unaltered. The Z24 head has square intake ports with rounded corners while the Z20/22 are round, usually with injector notches. Z20/22 heads will work on a Z24 if you use Z20/22 intake gaskets. A Z24 head is the better option. The Z20/22 heads has an opening for the mechanical fuel pump but on the EFI models and the 720 with electric pumps have block off plates. All valves and cams are the same.

 

* Mileage Option Z20S head W04 casting. Otherwise identical, but has smaller combustion chambers and two small quench areas. Compression on the Z24 would be too high at 9.5.

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And I have a couple z24 and 1 z22, but I've never even touched a z20 :)

That Z20 I have is a unique block.

I normally would have just scrapped it out, but once I tore it down to the short block I realized it was special, it has 6 inch rods in it with flat top pistons.

 

The Z20S head from the 720 mileage option (casting number W04) should be avoided* but the A10 and S110 200sx Z20 head is identical to the Z22 heads from truck or later S110. Naturally a Z24 head will always be the best fit. All three (other than the Mileage Option) have the same combustion chamber size (I have two of each and have cc'd them) so the compression will be unaltered. The Z24 head has square intake ports with rounded corners while the Z20/22 are round, usually with injector notches. Z20/22 heads will work on a Z24 if you use Z20/22 intake gaskets. A Z24 head is the better option. The Z20/22 heads has an opening for the mechanical fuel pump but on the EFI models and the 720 with electric pumps have block off plates. All valves and cams are the same.

 

* Mileage Option Z20S head W04 casting. Otherwise identical, but has smaller combustion chambers and two small quench areas. Compression on the Z24 would be too high at 9.5.

Where would the casting number be on the head?

All 3 look exactly the same to me.

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Front left side half way up. On the bulge for the timing chain and sprocket forwards of the #1 exhaust side plug. I just checked a Z24 and a Z20/22 and that's where I found it. I don't have a W04 casting.

 

WP_20140218_003.jpg

 

Take note that the '80 Z20 engines had single plugs while those for the California market were dual plugs. All '81 and on Z20s were dual plugs..

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I have a an 84 with electric fuel pump dual plug. I look at the head for the casting number, it reads OW 6. With the ow being above the #6. I really do enjoy the engine and its characteristics. But the people that have been giving me help at the track days. Saying that I might try going with a little more power to help break the tire lose.

So I thought for the money I'm gonna spend on a new head to run the same power or put it into a swap. I have done swaps before including a 3.8 Buick V6 in to a miata and and 2.3 turbo Ford in to an 5.0 fox body.

I rather not run a higher compression as I worry for detonation. I run the engine In low gears at high revs because of the track having no straights.

KA does sound like a bad idea but a lot of the 240 guys say there not that reliable with such abuse. And I've never had a problem with my Z motor other then the head. Even with the everyday abuse of the track. If I wasn't having this problem I would be spend the time on the diff and suspension. As they will be better to have then more power. But since it's where it's at now I thought might as well so I don't have to do it again down the road.

I have looked on eBay but I worry there might a problem with it like the head that came on the truck and they don't to seem to hold up to hexi-coils.

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What exactly is wrong with the head you have now? Because all Z24 heads have the same valve size and same cam. In addition the Z series head is a poor design for power or added power in the first place. You can maximize it's potential by running a weber 38/38 and using a 'turbo' muffler. Because of valve position you can't run too much lift and duration or they will touch.

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My buddy brought the truck and was changing the spark plugs on the second plug it's snapped off at the treads so he gave up .

I brought it had a machine shop install a new hexi-coils in four spark plug. Three months down the road the coil shoot outta the engine. so back to the machine shop again . Second set double over size and just like clock work happened again. But only the two exhaust side. Took it back and they said they can't go bigger. As the spark plug will hit the piston face

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I'm not sure I understand how installing a thicker heli coil would suddenly make the plug hit the piston. When that type of repair is finished, the plug sits in the identical place it started out at...

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