N42 or N47 on a L28 block

[footballnick17]

I have an L28 block, which head is preferable?

 

 

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[Zed Head]

Those two heads are essentially the same.  The exhaust ports are different though, so you need the right exhaust manifold.

There's another style of head for the L28, either a P79 or P90.  It came with flat-top pistons.  The N42 and N47 came with dished pistons.

[siteunseen]

I have an N42 head and block, car runs great. '75 and '76 were N42 combos. N47 came in late '76 with round exhaust ports and "liners" to help burn unburnt fuel. They would get glowing hot and all I've read decreased the exhaust flow. If you can find an N42 and port match the intake to the head you'll have a better flowing motor, happier motor.

[footballnick17]

Thank you, what do you mean by "port match the intake to the head"?


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[Travel'n Man]

Port matching is here you get the block ports and the intake ports from the head and match them with the exact same measurements and remove metal so they are matched once the are assembled together. This always more free flow airflow to occur for greater horsepower

 

 

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[footballnick17]

Okay, sounds fun


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[footballnick17]

Thanks


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[siteunseen]

16 hours ago, footballnick17 said:

Thank you, what do you mean by "port match the intake to the head"?


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here's the difference in intake ports from my intake to an N42 head that I used instead of a N47 head that came on my '77.  Small hole going into a bigger hole on the cylinder head side.  I marked the cylinder head holes on a piece of gasket paper then laid them on the intake.  Took a sharp scribe and scratched around the smaller intake holes.  Then used a grinder to open up and roll the edges like a bugle.  Quick and easy way to move more air, more air=quicker revs.