Z24 Head Swap

[NicktheMillwright]

Good afternoon

 

So in April I made a post asking about turbo options for the Z24, basically its a waste of money. But reading over Mikes comment on that post. He mentioned 2 things;

1. He would throw a L20 Head on it before he would turbo it, and

2. A KA24E head will bolt on as well

 

Lets skip 1 for now, because by chance a buddy of mine was parting out a KA24E, head and Pistons included. Online ive seen alot of people claiming that they have done it, but I cant seem to find anyone explaining how they did it.

 

I see a major issue right off the bat.

- The timing chain sprocket for the KA24E is single chain, while the Z is double, same pitch and roller diameter, and from what I can tell same length, but different sprocket. Was there a solution to this problem? Its not like you can use the z sprocket as the KA24E is Keyed in. I could use a broach and make a keyway for it, but if there is another solution that I dont know about, im all ears.

 

The more I think about it the more im willing to try out a L head, but finding a good L20 here in BC is proving difficult to say the least. Hence why its on the back burner

 

If anyone here has some insite to the KA head on a Z block I'm all ears. I know I could just swap the entire KA24E engine into the truck, but common, where's the fun in that?

[datzenmike]

While the KA head will bolt on some work is needed. There is an oil drain back hole on the KA head that will open into a coolant passage in the top of the Z series block. The KA combustion chambers are larger than the Z24 so compression will drop to about 7.6 so KA-E pistons pretty much have to be swapped in to raise it to 8.7 (want to stop now?)

 

An L head will need the Z24 block to be tilted about 18 degrees to the right side using L series engine brackets. Then the transmission mount will be twisted, so either get an L series 5 speed or put an L series front case on your Z series transmission to convert it to L series. A U67 or W58 will have smaller combustion chambers and make 9.25 compression.

[NicktheMillwright]

Side question, why is it critical to have the block turned 18 degrees?

[bottomwatcher]

Don't worry plenty of "fun" swapping the KA. If the truck body is good the KA power is way worth it.

[datzenmike]

8 hours ago, NicktheMillwright said:

Side question, why is it critical to have the block turned 18 degrees?

 

The L series block leans over to the right 12 degrees from vertical leaving more room for the intake and exhaust manifolds. Z series are about 8 degrees to the left. If L series manifolds were put on a Z series engine they won't have much room with the brake booster and steering column in the way, also the carburetor will be on an 18 degree tilt downward.

 

The transmissions reflect this tilt also. The Z series transmission would have to twist 18 degrees to the right to bolt up to the new position. The rubber mount would never accept this and the shifter would be in the passenger's hip.

[Stoffregen Motorsports]

15 hours ago, NicktheMillwright said:

Good afternoon

 

So in April I made a post asking about turbo options for the Z24, basically its a waste of money. But reading over Mikes comment on that post. He mentioned 2 things;

1. He would throw a L20 Head on it before he would turbo it, and

2. A KA24E head will bolt on as well

 

Lets skip 1 for now, because by chance a buddy of mine was parting out a KA24E, head and Pistons included. Online ive seen alot of people claiming that they have done it, but I cant seem to find anyone explaining how they did it.

 

I see a major issue right off the bat.

- The timing chain sprocket for the KA24E is single chain, while the Z is double, same pitch and roller diameter, and from what I can tell same length, but different sprocket. Was there a solution to this problem? Its not like you can use the z sprocket as the KA24E is Keyed in. I could use a broach and make a keyway for it, but if there is another solution that I dont know about, im all ears.

 

The more I think about it the more im willing to try out a L head, but finding a good L20 here in BC is proving difficult to say the least. Hence why its on the back burner

 

If anyone here has some insite to the KA head on a Z block I'm all ears. I know I could just swap the entire KA24E engine into the truck, but common, where's the fun in that?

I built one, once. A long time ago. I thought I remembered which car it went in, but I just checked and that car has a full KA24E in it. - https://bringatrailer.com/listing/1972-datsun-510-ka24pwwwr/

 

The timing chain set was all custom, and if memory serves, I used a Toyota 22R or RE upper cam sprocket, which I machined to fit the KA cam. I don't remember if we lengthened the chain or if the Z24 chain fit.

 

The cool thing about the KA head on a Z24 is that you can use stock motor mounts, stock water pump and accessory drive. Even a distributor if you're running carbs.

[Stoffregen Motorsports]

A cooler swap is to put the KA head on a built L20B/Z20 bottom end. Then you've got short stroke and a massively higher RPM range.

[datzenmike]

The KA-E combustion chamber is about 20cc larger than the open chamber L20B head so 6.5 compression. Flattops would get rid of 11.36cc. Decking the block 0.5mm would safely get rid of 3cc, milling the KA head 1mm is good for 6.2cc Don't know what the valve to piston clearance would be. Maybe a custom 20cc dome piston.

[NicktheMillwright]

From the sounds of things a complete KA swap may be simpler, cheaper and offer more hp. The limitation being the Z transmission.

[Charlie69]

The z trans bolts up to the KA, many Kaswaps are using the 720 z 5 spd trans.

[datzenmike]

The 71B would handle the 280zx non turbo so 150? Nissan didn't think it would last in the 180 hp turbo car

 

The 71B was replaced in '84 on the zed car and '86 on all other vehicles, long before the KA was even thought of. But yes, I would run the 71C if I had the choice, it handles at least twice the power.

[Dguy210]

9 hours ago, Charlie69 said:

The z trans bolts up to the KA, many Kaswaps are using the 720 z 5 spd trans.

 

6 minutes ago, datzenmike said:

The 71B would handle the 280zx non turbo so 150? Nissan didn't think it would last in the 180 hp turbo car

 

The 71B was replaced in '84 on the zed car and '86 on all other vehicles, long before the KA was even thought of. But yes, I would run the 71C if I had the choice, it handles at least twice the power.

Yep, what I'm running on my KA swap as it puts the shifter in the stock location, I'm also just using it in a very light car (1200)though as it is not as strong a transmission as some of the others. Depending on particular arraignment might need to drill out to use bolts for the starter instead of studs (very easy though).

[datzenmike]

You had a 71B that had studs for the starter? Maybe someone put them in. The transmissions all have tapped holes for starters (or studs)

[Dguy210]

9 hours ago, datzenmike said:

You had a 71B that had studs for the starter? Maybe someone put them in. The transmissions all have tapped holes for starters (or studs)

 

I think it was the engine block that used studs and the transmission had the holes? I don't remember exactly, I just remember there being an extremely mild change needed.

[datzenmike]

 

The car KA  blocks had this skirt that covered the entire front of the transmission where the engine plate would be on the L and Z series.  I got this block from an '89 S13 but no transmission. For the S13 diagrams show bolts holding the starter on from the transmission side and nuts on the starter side.

 

The D21 Hardbody KA engines bolt on just like the L and Z series, there is no skirt and an engine plate is used.

 

 

Probably you drilled out the starter holes in the block and used regular bolts from the front into the threaded holes in the transmission.

[Dguy210]

On 9/28/2022 at 7:01 PM, datzenmike said:

 

The car KA  blocks had this skirt that covered the entire front of the transmission where the engine plate would be on the L and Z series.  I got this block from an '89 S13 but no transmission. For the S13 diagrams show bolts holding the starter on from the transmission side and nuts on the starter side.

 

The D21 Hardbody KA engines bolt on just like the L and Z series, there is no skirt and an engine plate is used.

 

 

Probably you drilled out the starter holes in the block and used regular bolts from the front into the threaded holes in the transmission.

"Probably you drilled out the starter holes in the block and used regular bolts from the front into the threaded holes in the transmission."

 

That sounds about right I guess, it was probably about 10 years ago. 

[datzenmike]

Somehow I have the starter. I don't remember if or how it was attached.