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N42 head F54 block


CaptainJoe87

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I am about to become the owner of a 76 motor (N42 head from my research). I currently have a P79 head with the F45 block. I read on datsunzgarage.com that "Many people like these for performance because of it's square exhaust ports. And as a easy mod, putting it on a flattop L28 motor puts compression in the mid 10's." What are the advantages and disadvantages of this setup over my current setup? What type of power gains are to be expected in doing this? If I can get a bit of an upgrade from this setup while saving some money to fix up some other things then that would be awesome. I have tried searching but everything I am finding if for a 3.0L setup. Any information or links to information or anything that can help would be greatly appreciated.

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I just built an F54 / N42.

Many say the mid-10 Compression Ratio is a little much.

 

I am running a fairly "large" cam which puts my Dynamic Compression Ratio below 8:1 even with the Static Compression at 10.2:1. Supposedly that will help with rattles.

 

Haven't run it yet seeing as I dropped it off the hoist last night...

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If you search around on here, you'll find a lot of info/ discussion about this combo.

Im running this setup with a .490 lift, 290 duration cam and its fine for daily driving, and generally cruising around in. Due to the chamber design it pings VERY easily once you give it more throttle, and so you'll have to back timing off accordingly.

I'm going to run megajolt on the motor and see what I can do to get around this issue, but in the end I'll probably end up getting a better head as the current combo is not quite what I had hoped it would be.

IMO, an unmodified N42 on flat tops is not an ideal motor for the street, but to each their own.

 

Rob

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I believe its an older schneider cam. Not quite 100% on that, as I was given it by a friend. Before this motor the car had a very much stock motor, n42 head, block, dished pistons etc. etc.

 

I would say the new motor feels like it has more potential, and it definitely could develop more power. The problem is it just pings very easily, so to have something thats driveable on a daily basis you will probably find you're going to pull a fair bit of timing. And in that state, its very driveable, but down on power and pretty much comparable to a stock motor in my opinion. As far as throttle response, I think you will find that is more dependent on your flywheel choice and tuning of the carbs or ecu. I am running a stock lightened flywheel (around 13lbs) and triple 45mm webers, and I'm quite happy with how the car runs, drives and responds to throttle input. I do feel however it could be much better if timing could be advanced.

 

If I were you, I would keep your p79 on the motor, and then if you really want a hotter combo get the n42 worked on and then put it in your car. After all, its the ideal head to modify, and you'll probably be happier with the results.

 

Hope that answers some of your questions!

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Thanks Lazeum for the link and Rob for the explanation. This car isnt my daily its just a for fun and weekend car. I was planing on getting some head work done, probably porting it and possibly a cam and valve job depending on cost. I do not have carbs though, I was planing on keeping it fuel injected. My goal with this was to have something that was A.) better than stock B.) something that I would spend under $1000 with working on and C.) a fun little hold over so I could work on some other things and get this car in better shape. I got the whole motor, intake, and headers for free so Im off to a good start cost wise. Getting straight pipe run from the header is maybe $200 and I already have a muffler. Now that I have those headers I might donate on here and try to sell my other ones. Should be able to as I got them and never hand a chance to put them on the car.

 

I read probably three pages of that link, thats a lot of information to take in. Im going to have to take some time out and read the whole thing some time soon, before I start working on it.

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  • 2 weeks later...

i just did a build you described but im using an n42 block cuz its what i had already lol, flattops with n42 head and block with ms2 v3 pcb running direct coil control with zero tuning and i have yet to hear it ping. i am however running a cam with lots of duration (comp cams 292s grind with a whopping 5 inches of vacuum at 900rpm idle )and i feel it to be very streetable although i agree with duragg in the respect that the cam helps keep the compression down and while it doesnt ping, my rust bucket does like to rattle. anyways i think you can pull off what you are looking for in terms of pricerange and fun factor if you are just talking about engine work and mild tuneup. ive spent about 2500 and my z looks worse than when i bought it. anyways, have fun!

marcus

 

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So far my F54 / N42 / Triples combo is doing well.

Taking some time to get the Triples dialed in and just installed a Wideband Saturday.

 

Haven't been able to drive it much since I am still dialing in the fuel and having heat-soak problems with the carbs.

 

I haven't heard detonation, but the darn thing is pretty loud and not sure I would hear it???

Presently there is 15 initial and 35 total advance. I might pull that back a bit before I start romping it.

210PSI compression on all cylinders. TOTAL SEAL RINGS!

 

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I guess everything keeps coming back to mega squirt and cam or carbs. I just got home from vacation so the reading begins again. If I can sell this motor as a whole I might not be doing this setup, but we will see how it goes. I have a couple people interested in it so if it falls through then Im going to have to make the best out of what I have. Really trying to get some money saved up to get the frame rails and floor pans redone first and foremost though.

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I just ordered a "Knocksense" from Boris Mohar in Canada.

borism @ sympatico.ca

 

Standalone unit with a sensor, control box, LED and wiring.

He needs the cylinder bore to tune the device.

 

Light goes off when the rattles begin is the theory.

 

Will advise how it works.

 

TJ

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  • 2 weeks later...

Ok so I have started pulling the motor apart, just need to take it to my friend's shop to get the head bolts and crank bolt loose and then off with the head. Question though so I know what to keep and what to sell off, round headers can go on round or square heads but square is only with square right? Or is it the other way around? The motor came with square headers and I have a set of round ones that I got for the motor in my car already. Hopefully ill have the head off by the end of today and then its time to start pricing out machine shop options. Anyone know any good ones in the Baltimore Maryland area please let me know.

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