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N42 head questions


Victor_Zedman

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So as some of you know my N42 cylinder head is damaged and warped so i bought one from James (JW Sport Cars) He gave me a great deal for a rebuilt n42 head. Heres the thing tough my head i had before is an N42 with an internally oiled p90 cam. The N42 im gettting from James doesnt have an Oiler, so what im asking is can i swap in the p90 cam on the N42 Head im getting. or should i find an oiler will the compression ratio lower a lot. I have the old head's rockers and cam towers

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Thanks for the reply man, so will i have to transfer my cam with the towers?

 

The cam tower will physically fit. You will need to follow the FSM instruction for setting up the head explicitly. Make sure you shim the towers if needed, check the lash pad thickness, and rocker wipe pattern. Nothing just "swaps" without checking.

Edited by ctc
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Here's the thing tough my head i had before is an N42 with an internally oiled p90 cam. The N42 im gettting from James doesnt have an Oiler, so what im asking is can i swap in the p90 cam on the N42 Head im getting. or should i find an oiler will the compression ratio lower a lot. I have the old head's rockers and cam towers

 

So you are going from a internally oiled n42 to a internally oiled N42 right?

 

Just swap the cam, rockers, valve stem top caps. Leave the towers in place unless there is a real reason not to. Measure the thickness of the new head from the deck to the surface the valve cover bolts to, if its within spec, no cam tower shims are required. Check the cam wipe pattern on the rockers, adjust if needed, odds are you won't have to adjust anything unless the new head was super shaved or your old head was shaved and the new head was not etc. But if both heads are close to stock, it should be plug and play. If you are unsure...a good machine shop should be able to help you figure it out.

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OK awesome man, The cam is a P90 internally oiled one, will i lose power?

 

If you are running the stock n42 block, which has dished pistons, your compression ratio will drop to about 7.3 with the p90 head. It will feel noticeably slower.

 

 

I was considering the better flowing p90 head on my n42 block for a bit, but unless you are planning on also swapping the pistons for flat-tops (to keep compression up) or going turbo (where you may want a lower CR), it doesn't seem to be worth it.

I just replaced my stock n42 head (with spraybar) with another n42 head (internally oiled).

Edited by 8DC
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  • 1 month later...

I just did this on my turbo n42 build. Find a complete internally oiled cam setup, n47, p79, p90 non hydraulic. Take the cam towers, and cam, associated rockers and lash pads, it will work just fine. Just MAKE SURE you use the proper cam towers that came with the internally oiled cam. I have some internally oiled cam towers if you need them. Paypal only, $40 shipped - sk84life1122@sbcglobal.net

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