If you get a book on Z engine mods you will see that it's a big, expensive job even for the experienced mechanic. An easier project would be to put on a set of headers and two air cleaners. You will gain about 15 HP and you can do it yourself in a day. You won't gain much of anything from a cam unless you do this anyway.

 

if you're going to purchase one from msa the warranty requires you to replace the rocker arms. they say its good to replace the lash pads so you don't wear on the lobes but i've heard you can just resurface (in a way) the existing ones so it doesn't effect the new cam. you'll also want to replace the springs. The cam may not give you a big boost in power but if you're going to do other mods like the header, 2 1/2" exhaust, bore, etc it wouldn't hurt. at some point though it becomes cheaper just to slap in a V-8 unless you're nastalgic and want to keep the stock motor. i'm sure there's other things that need to be done but that's all i know of.

 

The Cam basically lets the engine breath better at a higher rpm range. The more radical the cam (longer duration) the higher that rpm band is that it breaths at... aslo, the higher the rpm it is made for, the more torque you lose and the more rough your idle becomes. But the cam itself doesn't add all that much power.

Go with a mild cam on your stock engine and do some intake/exhaust work too. If you want a more radical cam you will need to make sure you raise your compression. Higher compression, ported intake, and properly tuned carbs are where the power comes from, the cam allows it to work good at 6,000 rpm. The stock cam just runs out of breath, literally. The valves are opening and closing so fast as that rpm that the short stock duration doesn't get much air and fuel mixture in the engine. That's why it has less power with the factory cam. But the short duration. Closes the valves in plenty of time so that you have maximum compression at low and midrange rpm. There has to be a good balance, and your average drive doesn't use the engine over 3000rpm much. That's what Nissan made the cam for. (plus more torque means you'll get better gas milage overall)

 

probably. it would be better if you added a 2 1/2" exhaust as well. better flow, better hp.

 

honestly, i'd go with the msa 6-1 header. there's really no point in doing the 3-2-1 unless you plan on going with dual exhausts in the future. either way i don't see that it would affect your performance. I don't have a whole lot of experience with performance mufflers on the z but allmyzs (a member here) has a flowmaster exhaust on his and it sounds damn good. flowpro mufflers are pretty good too. i don't know if they make a universal exhaust or if they're for specific applications. i would imagine they do though. if you buy the turbo exhaust setup off msa it runs 2.5" pipes all the way back. does yours have a cat? they make them either way. i've seen the first gen z's with those, too and they sound pretty f#*%ing good, as well. whatever you do though, just don't put one of those rice rocket exhuasts on there! i'm sure you won't you've said before that you would like to keep it as stock as possible. i loathe those things so i had to put that in there.

 

yeah, that's right. it's an overhead cam so it's right up there with the valve train. i'm not sure which z your referring to but i've never posted pics of mine. i'm still working on mine.

 

Good luck with it. Although, I've heard that swapping the cam is anything but easy. There's another post on it from a while back that tells you all about it. It may have been at zcar.com. It's a hell of a lot easier with the sohc setup, but it's still not easy. Let me know how it goes though. I plan on doing mine this summer.

 

I have modified 3 early 240Z engines and I am working on a "proper" L28/E31-E36/4screwSU combo.

I will say that the L6 sounds better with a mild cam(baritone..trombone sound @3-5k)....It will also refuse to hold a constant idle speed with SUs and any performance cam. The timing of any performance enhancing cam grind will cause reversion at low engine speeds...this causes the carbs to spew gas and generally fail to function properly at low speeds. Ignition upgrades and velocity stacks on the throats will help greatly....but the last thing you want to address is the exhaust system. You see....the L6 engines are not as good at breathing as a modern 4 valve/variable timing engine design. Early Z motors NEED some backpressure to operate properly in a variety of conditions.

you must replace rockers and lash pads as a set and have a mechanic check the "wipe" pattern between the lobes and the rocker pads. Valve springs get old and are inconsistant even after just 10,000 miles or a few years sitting unused in a garage. The added stresses from higher lift cam grinds will cause float and even damage to the rocker pads and cam lobes at high RPM. A "good" cam installation is really half the money spent on a "good" head rebuild...you might as well do the whole job right...because cleaning up the old chambers and valves will also greatly enhance performance.

Seriously...stick with a very mild "tuner" grind....You really NEED to increase compression ratio to use an agressive grind....also keep in mind that EVERY TIME the humidity changes...or the temperature varies by more than 20 degrees....you will wish you had the time to retune the timing and carbs.

About the exhausts....All of the systems I have seen and used are intended for all out top end with no provision for low end performance....You will find that dyno runs of Z cars with those header/straight pipe installs will have a dip in torque around 4000 RPM....that is because there are terrible resonances in the long straight tailpipe...you really need to retain a small straight-through pre-muffler as close as possible to the collector...2 1/4" tubing is best for street and auto-x....use any muffler you want at the end. also...I would also add a flex joint to the end of the collector...to save your header and intake bolts around town and rough streets.
I built a really expensive system incorporating all of the stock features..but in stainless with 6-2-1headers...It sounds great....but really similar in volume and tone to a stock system. cost me almost $1000...for a freaking 240Z no cats.

 

Having people going off theread like this will ruin this web site. t: BleachZee and or bjhines I have a continuing question , what HP is expected from the mods . Cam, ignition , 9.5 to 1 compression , headers /w 2 1/2'' plumbing , from a 82ZX flat top with SUs properly tuned.

 

Well.....you will have to generalize on the HP rating....You can "tune in" 200HP with that set up....but you will not always have a fast car...just make sure you can wind it out to 8500 RPM without a significant drop in torque....doesn't mean the car is fast though.

Your engine has a limited ability to run well at all speeds....good low end torque will get you a lower HP reading than an engine tuned to run well at 8500 RPM.

You have not mentioned balancing, polishing, port matching, valve seat grind angles....bowl skirting...lightened flywheel.... high squish area E31 or P90 head...... or any of the typical all out high HP preparations...not to mention all of the hundreds of things builders do to make an engine survive constant high RPM racing conditions.......$2000 dry sump comes to mind....fuel and intake cooling....high ignition advance with water injection...$2000 variable timing knock sensing, crank triggered ignition. plus.....Those SU carbs can be modified to flow better.....

I can only assume you DO NOT WANT HIGH HP. If you want the best of both worlds...then go buy something with a 4 valve V-TEC engine.

You can only hope to make the engine "feel" good...you will not make a normally aspirated daily driver that puts out twice the HP of the original engine. It aint gonna happen...ever...
even if you get it to feel right...Dyno runs with a carburated engine will vary WIDELY from run to run/ day to day.

People have forgotten the days when our older engines were unpredictable.....you step on the gas and sometimes it feels like a million bucks....sometimes it just sputters and coughs it's way to redline.....cold day flat spots and burnt points were a fact of life....modern engines can go 100K miles without changing spark plugs for god's sake....
Those SU carbs are actually a fantastic combination of reliability, good flow, and good feel. luckily you have an electronic ignition on yer 280.

I would spend more money on the brakes for your car than high dollar engine mods.....ohh....and the 280ZXs are damn near 1000 lbs heavier than the first 240Zs....240Zs dont need all that HP to embarass you anywhere on the track....better acceleration...better cornering...better braking......Wider tires make for a faster track car than dragster.....

This can go on for days.....the fact is that smooth application of tourque and reliable, consistant performance will allow the Z cars to shine @ what they do best.....high speed on windy roads....if you want a dragster go buy another car....or get a V-8.