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Are NAPS z24 headbolts same as ka24?


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#1 Spades

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Posted 15 December 2010 - 10:50 AM

I noticed from some manufacturers that KA24 headbolts for a 720 are the same part number as the headbolts for my 86 naps z24 engine...are they the same from Nissan?

The reason I ask is that ARP doesn't list studs or bolts for a naps motor but they do for a KA24.

I am going to pull the head on my built naps motor because the machine shop the assembled the engine didn't torque or install the timing cover properly and it is puking oil, not to mention I think the timing chain is a tooth off(in order to get it to run decent and get decent gas mileage I have to run 14 degrees advance on a 8 plug naps motor!!!!).

I figured if I had the head off anyway I would replace the head bolts. Should I just buy Nissan headbolts? We have had good luck with Stone gaskets from IMC, are they as good as a factory head gasket?

P.S. I do plan to re-torque the head after a few thousand miles to accommodate for slight headbolt stretching

#2 nis720

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Posted 15 December 2010 - 12:06 PM

I wondered the same thing. Here's measurements I took of my KA24E headbolts.

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Here it is next to the KA24DE application ARP stud.

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#3 Spades

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Posted 15 December 2010 - 12:22 PM

If no one knows for sure, I can order a set of each from my suppliers and see if there are any differences. From what I have read, they are the same length and thread pitch, I just wonder about if there are any bolt differences as far as how much the threads stretch, ect. I know both engines take about the same torque numbers.

Anyone have any thoughts about this? I am thinking about using a flat board to sand the top of my block when I pull the head since I know the head was shaved and the block was not. Any thoughts? Are Stone gaskets better quality than Nissan gaskets?

#4 datzenmike

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Posted 15 December 2010 - 12:31 PM

I can look up the Nissan Pt.# when I get home in a couple of hours. This is good to know if it is.

#5 Master-O-Turbonics

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Posted 15 December 2010 - 04:03 PM

Here it is next to the KA24DE application ARP stud.

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Looks like only 5 threads would engage. That should get the nut completely on the stud but it may not stretch the head bolt enough when torqued to spec because the stud is effectively longer. (needs more torque to get proper bolt stretch)
Also looks like less of the stud threads into the block, which would put more stress on the block (may not be good for Z24 block which already has issues there)

#6 MicroMachinery

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Posted 15 December 2010 - 04:06 PM

Are Stone gaskets better quality than Nissan gaskets?


Stone is just another aftermarket company. As far as them being better? I wouldn't count on it. Especially for headgaskets. I'd stick with Fel-Pro if you're not going to get factory stuff. Fel-Pro is pretty inexpensive and proven good quality.
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#7 Spades

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Posted 15 December 2010 - 04:33 PM

I have had really good luck with Felpro, we use them on domestic cars all the time since most of our customers do not want to opt for the more expensive dealer gaskets, however, I personally have only used Felpro a few times on imports, and I have used tons of Stone head gaskets on Nissans with no come backs or leaks. They seem to be good quality, which is why I am asking about them.

As far as why I was thinking about trying a different head gasket other than Nissan, is because it sounds like they blow up at 100k miles...figured I would ask.

As far as the headbolts, I could call our dealer and find out if the Nissan part # is the same, I just hate to bother them since I will only be ordering the Nissan headbolts if I cannot find a ARP or better-than-stock stud or bolt.

#8 datzenmike

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Posted 15 December 2010 - 04:51 PM

Z24 head bolt (all) ....................... 11057 H5700

S13 and D-21 KA24E bolt .......... 11057 H5010

#9 datzenmike

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Posted 15 December 2010 - 04:59 PM

As far as why I was thinking about trying a different head gasket other than Nissan, is because it sounds like they blow up at 100k miles...figured I would ask.


Nissan has a cure for the Z24 head gasket failure problem. It recommends that ON A COLD MOTOR, you loosen each head bolt one at a time and re-torque to spec (60) ft lbs every tune up. You do not need to do in any sequence just loosen and torque one at a time. EVERY TUNE UP. This removes any looseness from gasket crush and thousands of hot cold cycles and keeps the head firmly clamping at 60 ft lbs.

Hey you have to check the valve lash anyway so torque the cold head first. How hard is that if it helps?

#10 Sealik

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Posted 15 December 2010 - 05:04 PM

I just pulled a stock Z24 head gasket......measures 90mm.
The new Felpro.....measures 91.

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#11 datzenmike

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Posted 15 December 2010 - 05:27 PM

I was hoping the stock was larger than the bore. Remember I said it shouldn't hang out into the cylinder like baloney in a sandwich. 0.5 mm back from the edge is good. Perhaps Felpro feels this is better for preventing burn through.

#12 Spades

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Posted 15 December 2010 - 05:30 PM

Nissan has a cure for the Z24 head gasket failure problem. It recommends that ON A COLD MOTOR, you loosen each head bolt one at a time and re-torque to spec (60) ft lbs every tune up. You do not need to do in any sequence just loosen and torque one at a time. EVERY TUNE UP. This removes any looseness from gasket crush and thousands of hot cold cycles and keeps the head firmly clamping at 60 ft lbs.

Hey you have to check the valve lash anyway so torque the cold head first. How hard is that if it helps?



Yeah, I have already done a re-torque on this head gasket after setting the valves the second time...but since Davison's screwed up and the timing cover is leaking and I suspect that the timing is off by a tooth or two, I am going to be pulling the head, and I want to be sure that this is done right. This is my plan:

*Remove the cylinder head and use a flat sanding block and lightly sand the engine block
*Buy new Nissan or Felpro head bolts
*Use a high quality head gasket(I am going to have to research to see if I want to go Nissan,Stone, or Felpro)
*Torque the head properly
*Put some miles on it, then when I set the valve lash, loosen and re-torque the head bolts

That's the plan as of right now. Doesn't look like the ARP studs are a good option, especially since Nissan has different part numbers. I will look into some Felpro bolts or new factory Nissan bolts.

#13 Sealik

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Posted 15 December 2010 - 05:33 PM

Yeah, I have already done a re-torque on this head gasket after setting the valves the second time...but since Davison's screwed up and the timing cover is leaking and I suspect that the timing is off by a tooth or two, I am going to be pulling the head, and I want to be sure that this is done right. This is my plan:

*Remove the cylinder head and use a flat sanding block and lightly sand the engine block
*Buy new Nissan or Felpro head bolts
*Use a high quality head gasket(I am going to have to research to see if I want to go Nissan,Stone, or Felpro)
*Torque the head properly
*Put some miles on it, then when I set the valve lash, loosen and re-torque the head bolts

That's the plan as of right now. Doesn't look like the ARP studs are a good option, especially since Nissan has different part numbers. I will look into some Felpro bolts or new factory Nissan bolts.



What kind of sanding block?

#14 datzenmike

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Posted 15 December 2010 - 05:38 PM

*Put some miles on it, then when I set the valve lash, loosen and re-torque the head bolts


Head must be cold, hate to nag, but you won't get the right clamping force otherwise. Just sayin'

#15 Sealik

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Posted 15 December 2010 - 05:42 PM

Head must be cold, hate to nag, but you won't get the right clamping force otherwise. Just sayin'



Minimum outside temp to install HG?

#16 Spades

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Posted 15 December 2010 - 05:42 PM

we have a couple of straight blocks here at the shop for this purpose, we normally use a very fine grade of sandpaper with this method and take care and time. We have done it in the past when we are concerned about the seal after having the head decked when they rebuild a head for us.

#17 Spades

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Posted 15 December 2010 - 05:45 PM

Head must be cold, hate to nag, but you won't get the right clamping force otherwise. Just sayin'



My plan with that is to pull the car(at operating temperature/hot) into the shop some Friday evening after hours, set the valve lash, and leave the car overnight with the valvecover off, and return the next morning to torque the head bolts.

No, I am not planning to loosen head bolts on a hot car...<<CRACK>>

#18 datzenmike

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Posted 15 December 2010 - 06:27 PM

It won't crack or warp doing them one at a time but the metal is expanded from the heat. When it cools the torque will be less than spec. Aluminum expands twice as much as steel.

#19 Spades

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Posted 16 December 2010 - 11:44 AM

I doubt a head would get damaged by one bolt at a time, but once I saw a idiot pull the headbolts from the front to the back on a hot car, and it cracked.

but yeah, i know that it expands, which is why you set valves when warm, especially on a engine with aluminum cam towers.

#20 Spades

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Posted 17 December 2010 - 12:33 PM

So, to sum up this thread, the head bolts are NOT the same part # according to Nissan, and I would rather go with Nissan headbolts than the ARP studs shown. It seems to matter more about the prep work and routinely checking the headbolt torque rather than the quality of the headbolts used.

With all that said, I looked at the Stone gasket I have here, and I will be using a Felpro instead...the stone gasket for this application looks pretty cheap, which is humorous since it is more expensive than the Felpro gasket.

So, I will be very careful with the prepwork, installation, and re-torquing of the headgasket when I start this project.

Thanks for the help everyone!