ka24e pistons in z24 block.

[nissan720]

i want to put ka24e truck pistons in z24 block.i know the bore is the same.the dish in top of piston is different so it will raise the compression ratio.i don't have a problem with that.will i have to have the top of the piston cut for valve relief ?also did nissan make a 370 gear or 410 for the 720?making hp the old school way.

[datzenmike]

Yes, stock compression on the Z24 is 8.3 or just under. KA24E pistons will raise it to 9.52. Valve reliefs?... don't know. Exhaust is closing and intake opening at TDC.

[medengines]

i want to put ka24e truck pistons in z24 block.i know the bore is the same.the dish in top of piston is different so it will raise the compression ratio.i don't have a problem with that.will i have to have the top of the piston cut for valve relief ?also did nissan make a 370 gear or 410 for the 720?making hp the old school way.

 

You will bend valves if you dont do this so "yes"you will have to cut pistons for valve clearance..

take to machine shop tell them you need it cut .150" (5/32) into head of piston..using the ex. and intake head diameter as a reference..this will give you enough clearance for the Web 300 cam, biggest web makes for this motor..they shouldn't have a problem doing this.

or you can set up a jig with an old cylinderhead and make a exh. / intake valve a cutter by grinding them into cutters..measure them for your depth and cut it by hand or with a drill..

[datzenmike]

I know they do some crazy shit out there in Guam with Z motors, so good info.

[nissan720]

thanks good info thats what i needed to know

[medengines]

Heres pics of a Z24 block with KA24E pistons with knotches cut and a stock uncut piston compared to it, give you an ida of what it looks like done up.

 

Here is some KA24DE pistons in a Z24 block bored .040 over with "fresh hone just done up" slight dish 9cc's now think its about 12cc's w/the cuts in them, these are shelf Wiseco Forged pistons I cut these for extra valve clearance and to lower compresion alittle for turbo use..will be swapping out the z22 engine with this one later(couldn't find shelf Forged pistons for the Z22's). Rather stick w/Z22's on boost for the added bore spacing though!

 

 

 

I'm getting ready to do another block this week so i'll try to take pics of the cylinder head jig and cutters and show some of this here.

[nissan720]

the valve cuts r they for the exhaust or intake.this info is helping me to put the pieces together.so forged ka24e truck pistons and the rest just z24 parts.will be using an after market cam.thanks medengines for all that info.thats a big help.it saves me a lot of guess work.

[datzenmike]

The intakes are the largest diameter the exhaust might clear without the relief cut?

[nissan720]

thanks ,i was not sure.now time to start looking for parts.

[Nissan_Boy85]

Might as well revive this topic since its on the same lines. How did you determine where the valve reliefs needed to be placed for proper clearance?

[_chiefjt]

This gave me a thought.

 

So say you put ka-e pistons w/ relief cuts into a z24. If one were to buy aftermarket connecting rods for a ka-e, would they fit in a z24? Something like Eagle Rods?

 

Also to answer your rear end question. Yes Nissan did make different gear ratios. More than likely your truck will have 3:7 gears in it already. The most popular one for swapping into a 720 is the 4:375 (4:38) rear end. You can get these out of 521's, 620's and I think 4x4 720's. Unless the 4x4 720's have the 4:11 or 4:8 gears. Idk, Mike knows. lol

 

I had 3:7 gears and swapped in the 4:38 out of a 521. My track time dropped a whole second. 

[Nissan_Boy85]

In theory yes, but KA rods are narrower then Z rods if memory serves.

[_chiefjt]

The stock KA rods are narrower than the Z rods. I'm talking about aftermarket rods which are stronger, lighter and more of a performance rod.

 

You could probably google search your question about the valve reliefs.

[Charlie69]

I always thought the stock Z rods are stronger than the stock KA rods.  What would be the benefit to run the KA rods?

[Charlie69]

All the 2 wd 720s I have checked had 3.899 gear ratio in them.  I ran across 1 1980 720 2 wd kc that had 4.11 in it with an L20B automatic.

[datzenmike]

My KA24E and Z24 rod (right) The Z24 appeared to he thicker, heavier... even the rod bolts were larger.

 

 

The KA rods would be lighter. I didn't check but the pin or small ends may have been narrower on one of them.

 

 

'80 720 2wd automatics used 4.375

The '80 L20B powered long bed 4x4 used a 4.625 differential.

Up to '82.5 the 4x4 used 4.375 and 4.11 after

The '81-'82 2wd automatics (long box anyway) used a 4.11

The '83-'86 Mileage option 2wd used a 3.364

[_chiefjt]

I don't know if you guys are getting what I'm talking about. lol

 

I'm not comparing STOCK KA rods to STOCK Z rods. I know the Z rods are stronger and what not but my question is:

 

Can you run aftermarket KA-E rods in a Z block if you use KA-E pistons?

 

For example, say I have an all stock z24 with KA-E pistons. Since I'm using KA pistons could I use KA Eagle Rods. So it'd be a z24 with KA pistons and Eagle Rods.

[datzenmike]

Don't see why not. I can measure the rod bearings from both.

 

Thing is KA pistons and rods are not going to make a Z24 make any more power. A slight increase from the compression, yes.

 

Power is made by the head.. port size and angle, valve size, cam lift and duration, valve springs, cross flow or not, hemi shape or wedge, closed or open chamber. The Z series have serious limitations for performance modifications.

 

Strength of an engine is built into the block internal parts... crank, rods, bearings caps and bolts. The block determines how strong the engine will be. KA after market rods would be good on a heavily modified KA engine. On a Z series they would be over kill. Stock KA rods would be lighter but strong enough for a Z24. The stock Z24 rods even better. 

[Farmer Joe]

might want to compare the FSM for the z24 and the KA24

 

the KA has 2 different main and rod sizes per what it came in.

 

truck KAs have 63.5mm mains and 59.9mm rod bearings. 

 

car KAs have 59.9 mm mains and 49mm rods. 

 

im not sure of what the Z24 crank specs are. mike might be able to help with that. 

 

heres a link to the KA info i was looking at. 

 

http://www.ka-t.org/forums/viewtopic.php?t=36861&start=0&postdays=0&postorder=asc&highlight=sohc+engine+specs

[datzenmike]

Farmer I have only a KA24E car crank and the mains are way smaller than the L and Z series, scary small. I have a set of car rods and had them on my Z22 crank and they looked ok. The rod I pictured (rusty) was from a D21 I know that threw a rod. It didn't have the crank girdle and were not floating pins so pretty sure was a truck engine. The two different rods look about the same although I haven't checked. Didn't know truck were different rod bearings so will look at that also.

 

49 to 59 is millimeters??? Thats one centimeter difference!!!!!! in rod big end diameters. One centimeter is 0.393" This would be noticable to the eye.

 

My KA24E and Z24 rod (right) The Z24 appeared to he thicker, heavier... even the rod bolts were larger.

 

Truck rod KA on left and Z24 on right. Will measure the car KA rods I have.

[_chiefjt]

Thanks Farmer & Mike. I guess the whole specs thing would have to be ran through the company selling them to determine wether it's for an early KA or later or car/truck KA.

 

I guess it would be overkill with performance KA rods but there's nothing wrong with strength and reliability.

 

So what would one do to build more power in the head? I'm talking about valves, stiffer/stronger springs, porting etc. I know a lot of people say a z24 is limited but I think it can make maybe 200hp on side drafts. Maybe it's even possible to run ITB's on it. What do you think?

[datzenmike]

It's all about breathing. The head is an air pump so the more air you can run through it the more power you can make.

 

The valves are opposite each other and close together so  larger valves, higher lift or more duration and they will hit. I think you will find that there are no radical 'race cams' for the Z series. A firmer spring would be a good idea

 

The intake and exhaust ports are almost horizontal with a sharp bend at the valve to enter the cylinder. Take a look at an L series intakes... the port is higher and falls down to the valve in a straighter line.

 

 

 

 

Some advantages of the Z head... hemi combustion chamber, cross flow, dual plugs.

[Ziggy720]

Do you have to cut the valve reliefs if you want to use a stock cam or can you get by without it?

[Nissan_Boy85]

The dish in a KA-E pistons is less then the Z24 (2cc in the KA vs 11cc in the NAP, I'm sure I will be corrected in this if I'm wrong) so I would imagine so but I can't say forsure. I happened across a set of true flat tops and had reliefs cut for a Isky 318 grind.

[datzenmike]

KA24E piston dish is 2.8cc. Z24 piston dish is 15cc. The Z24 has an 8.25 compression. With KA24E pistons it's 9.52.