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I just pulled the head off of a very poorly running L24 engine with an N42 head. My intent was to either rebuild the head or use the valves to rebuild an E31 head of mine. I figured that the E31 would be the better choice because the N42 would need to have the brass valve seats replaced anyways.

To my supprise, when I pulled the valves out, I found that the seats were steel!! Did they ever make an N42 with steel seats? Does this indicate that the head has been previously rebuilt?

I also found out why the engine was running rough. One of the exhaust valves was a valve from an E31 or early E88 head. It was smaller and marked differently then the others. The seat was the same as the other correct size N42 valves. The seat width was soooo small it looked like a hair line. Surely the valve wasn't sealing well.

I figure that someone rebuilt the head and needed a new valve so they grabbed one without checking the size. There sure are some crappy machine shops out there. Now I just need to buy a new exhaust valve for the mismatched valve.

The valve guides were steel also. I this normal?

Thanks for the help.

JT240Z
 

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Sounds like it was worked over by some PO.
Don't thing steel seats or guides were stock on any N42, but I'm not sure about that.

Some N42's have notches for FI, others not, I believe.

Later,
Al
 

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Yup, steel seets.

And they had steel giudes for the valves, too. An N42 head will not fit on an early L24 block without notching the top of the cylinders for the exhaust valve. The Valve WILL nick the block, to what extent ultimately depends on the final position, but the block needs to be notched. Sometimes the vlaves bend when they hit, sometimes they will run with no evidence until engine teardown.
 

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Re: Yup, steel seets.

It may be an import head,these came with steel seats etc.
My Australian N42 has steel seats and is a great head.
I don't know why the USA heads came with bronze seats when
the Jap, Aust heads were not. Nissan had some odd thinking then.
Cheers DavidU (aust)
 
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