Based on the rebuild I did on my L-24 a few years ago, I'll make the following semi concrete recomendations:  

The  motor (engine) that I built was bored .040 over for a total displacement of roughly 2.5 liters.  I used a set of pistons from Sterling that were flat top and cast.  I purchased them from a place called The Auto Parts Club if memory serves.  They are in The San Jose, Ca area.  Cost was about $100 for the six and I have no complaints.  If the original pistons are magnafluxed and look good, have them bead blasted, the cylinders honed (less money than boring over) and use new pins and rings.  If the motor is for daily driving and will not see the upper limits of operation (over 7000 rpm or so), I don't personally feel that the cost and "finickyness" of forged pistons are justifiable.  

For a car that is multi purpose and eminently streetable, stay away from the wild side.  If you are going to be using rebuilt SU type carbs that are pretty much stock, (hopefully roundtops!!!!)  and want usable torque and HP in the area indicated above, look for a cam with specs of about .475 to .495 lift on both the intake and exhaust and somewhere around 260 degrees of duration.  Anything much more will tend to starve for fuel.  Speaking of which, if the car does not have an electric fuel pump in the rear, consider getting one either to supplement or replace the mechanical one. IMPORTANT......when having the head done, if you have it milled to either increase compression or remove a warp, shim the cam towers the appropriate amount or the valvetrain geometry will suffer.  Also, replace the oiler spray bar if using an externally oiled cam/head.....it's WELL worth the 50 or so bucks.  For sources, look to either Motorsport or Arizona Z Car.  
Prices are comparable, but I lean to AZC for personal reasons.  AGAIN IMPORTANT!!!!!!!  please remember when installing a performance aftermarket cam that it is an integrated affair.  This means that not only do you replace the cam, but you replace most of the valvetrain.  Buy a matched set to include; the cam, double valve springs, rocker arms and valve retainers. You can pretty safely reuse the keepers.  If you don't get the components matched to work with one another, kiss the valvetrain goodbye.......trust me and expect to shell out between $400-$500 for the stuff that will last.  

Timing kits can also be had from Motorsport or AZC for usually around $100 complete.  Please do yourself a favor and buy a complete set including sprockets, chain and tensioner components.  It costs less to buy the whole shebang up front and saves yanking the engine to do it right later.  For the oil pump, Nissan did us a favor by engineering the 280ZX Turbo to use a beefier pump that will fit on any L series Z.  They can be had for less than  
$100 and are well worth the protection.  I would source one locally from Autozone or Pepboys.  You can also get a higher pressure spring to add more pressure to the higher volume turbo pump.  However, this requires the engine to idle up to temp before driving and I don't think it's worth it except for a race motor.  

I personally swear by Felpro.  The kit to do the whole engine is (again) about $100, but I've had really good luck with them.  For water seal areas, I use blue RTV to help seal.  Also, Permatex makes a copper impregnated aeresol that I used on the head gasket.  When I tore the motor down a couple of years ago, the seal was fantastic.  
Another note.....If you have gotten a header for the exhaust system, use a gasket that was intended for headers or it will leak.  Throw away the gasket that comes with the gasket kit.  

Finally, remember that success is in the details... especially with an L-6 engine.  If you are in doubt, replace it now and make sure it's right. If  I can be of any help, please let me know.  

Jeff Hagner  
Nuker@msn.com  

[10 April 1998 10:50pm -MSW] 

I think this is usually done after shot peening, and for similar reasons.Shot peening reduces the surface stress of the metal, and makes it less likely for cracks to start.  Polishing has a similar effect, in that by smoothing any surface irregularities, you are getting rid of the places 
where cracks are likely to start (failures usually start at sharp edges). I seem to remember a couple of metallurgist types being on this list - did I say that right? 

Sincerely, 

Tim Zwicky 
tzwicky@pipeline.com 
tzwicky@ford.com 

Hi Kyle, you sound like you are ready to go through what I just finished.  I built an L28 and got it running last summer and am very pleased with the performance in my 240Z (before it was broke in it ran 14.8 at 93mph at the 
drag strip, and my G-Tech Pro showed 0-60 in 6.07 seconds).  I've never added up the receipts (been afraid to), but here is what I did: 

1976 L28 with N42 head Head decked for flatness, good valve job, hd valve springs. Block decked for flatness, bored .040, used Nissan flat top pistons and rings. Had rods blueprinted, balanced, with new bolts Turbo head bolts, new flywheel and clutch bolts Turbo oil pump Schaffer cam from Motorsports (460 lift, 270/280 duration) Used genuine Nissan bearings, etc, replaced timing chain, sprockets, tensioner. Removed vacuum advance, recurved distributor with Crane electronic ignition Triple 40 DCNF WebersMotorsports 6 into 2 header, 2.5" exhaust from Motorsports 77 5 Speed, 3.90 R200 15x7 Panasports w/205-60 Goodyears I cc'd the head to calculate compression ratio, looks like about 9.5 - 9.75 to 1. 10 lb. Centerforce (Tilton) aluminum flywheel (ordered HKS from Motorsport; they said they can't get them anymore). 

Although it has a rumpity-rump idle at about 850 rpm, once it gets past about 1000 rpm it is as smooth as a baby's bottom and pulls HARD to 6500 where I shift.  Using the quarter mile time/speed, calculations show about 196 hp (and this was with a bad clutch that wouldn't let me shift to 4th; just screamed through the lights at about 7100 in third).  This combo might be a little radical for every day driving, but for a weekend/nice day toy it is great.  I haven't heard any detonation on 93 octane gas and it runs nice and cool, even with a 3 row 240Z radiator... 

Hope this helps... 
Don 

Kyle, 

It's going to be close...with my 3.2L,N42 ported/polished,510-300 cam and triple 40mm Mikunis, 6-1 w/ 2.5"pipe and Dynomax, I'm only at 250hp.  With the setup you're talking about, you may be at 200hp.  For under $2K...cam reground 490-290, $150 (anything bigger and you're going to have to get comp springs too),  new lash pads @$150 (a must with a new cam).  New timing chain/gear set $100. Valve stem seals, new seats and guides, 3 angle valve job. If you go up to triples, you can get a much bigger HP gain, but it's an extra $500-700 for a USED set.  With the SU's, don't worry about porting and polishing.  If you decide to, it's about $100 each (int/exh).  Pistons, I'd get the L28 flattops to boost your compression a bit (maybe shave a bit off your head too).  My Z24 pistons were $350 for the set.  You can probably go up .040" overbore (@$15 per cyl.) and still get stock L28 flattops to up your displacement a bit too. Plus $125 for Total Seal rings, $85 for Deves.  6-1 headers @$185, 2.5" exhaust and Dynomax @$200.  This could be pretty near 200hp.  Costwise, don't forget about all the "little" parts you need to get too (gaskets, etc), plus any machining costs (decking the block, the head, boring, etc.).  You're going to be at $2K or a 
bit over.  Building up the L-series engines is expensive as hell.   

Good luck Kyle. 

Stan Wada 

Hello Kyle: 
About that engine rebuild, I think that the answer to all your questions can be found at <http://www.geocities.com/MotorCity/2824/> 
This website was set up by Bryan Little in Richmond, VA. He documents the isdom of selecting various Z-car bits for best performance, explains how to put them together, and the results that you get. He has the same mix of parts as you suggest in your list below. (Only thing I didn't recognize was the reference to the "crossover tube work." He continues to evolve the car and is active in drag racing, so he gets real feed-back for every modification. I also like the fact that he endorses a stock-looking car, and enjoys getting performance from the original 6-cyl. instead of chucking it out in favor of a big old American V8. I've just purchased a 240Z and a 280ZX from which to take the engine and drivetrain and will be modeling my car on the proven example of Mr.Little's. The only stumbling block I've come across so far is the complexity of the fuel injection. Mr. Little is getting very good results with the Hitachi SU's, so I may just stay with them. They certainly look better. 
Good luck. 

-- 
Rob Roy 

Kyle - 

If you can do all of that for 2 grand, lemmee in on your sources! 

Seriously, I'd go like this; 

Engine - You might need bore and hone, pistons; you'll definitely need rings, bearings, gaskets, valve seals, timing set.  So you're in the $700 - $1000 range already.  Add cam, valve lapping, and springs, we're at $1500.  $2,000 is about right for a "stock" rebuild, but a little attention to detail can make that stock motor really pull. 

Have the engine balanced - worth every penny. 

They say "Power is made in the head"  Have that baby cleaned up, or do it yourself with good advice and supervision.  With the valves out, smooth out the runners, especially intake side.  Unshroud the valves, if you can.  If you look at a valve as it opens in the head, you'll notice that when the valve is open 1/8" there is less than this amount of clearance around the valve to the head.  What good is a monster valve lift if the restrictive point is in the combustion chamber?  Oversized valves are notorious for this because they actually reduce valve to head clearance on the sides, which is where the gases have to go to get into the chamber. 

I got a Pacesetter 6/2/1  header, had it ceramic coated - about $300 total.  Looks, sounds, and PULLS great. 

The BEST single piece of advice I got came from Scott Bruning, who said "Think of your engine as an air pump - the more air you can move through it, the power you will make".  Sounds simple.  Isn't. 

I'd get a good core engine to work on, so you're not down for six months while building your new engine.  There is an old saying (actually comes from construction, but it works everywhere):  there are three positives to every job - speed, economy, and quality - you can have any two out of the three, but not three at once!  Fast and cheap is low quality, fast and high quality is not cheap.  You get the picture. 

Can't help you on carb set-ups - I'm keeping my EFI on my '78 (plus turbo AFM, adjustable fuel pressure, reamed out intake, K&N, etc., etc. 

2 grand for the engine, plus carbs, header, and other goodies.  You might do better if you shop real hard.  Check out all the online bulletin boards for parts. 

Good luck!  Post me along the way? 

John

Hi Kyle,

As far as which head/block goes, I assume you are already going with an L28 block. I don't really think that is any major differences between any of the L28 blocks (75-83) with the turbo being an exception.

Assuming that your only choice should be which head. As far as things fitting your intake will bolt up to any year head, if you are planning on re-using your existing exhaust (which I assume is square port) then you are limited to using only a square port head. If you are going to, or willing to get a new header then your options are wide open again. I am not sure when it happened but somewhere in production (later) the hole for the stock mechanical pump stopped getting cast into the heads. As long as you are willing to get an electric pump in place of the mechanical (not a bad idea anyhow) then you are still wide open on your choices.

I had a decent write-up on all the different heads with pros and cons all listed, I probably still have a hard copy but since I changed jobs I no longer have the email.

What I hear most often is that the N42 is the best all around head to start with. It has the bigger valves, square exhaust ports, drilled for either FI or carbs, decent combustion chamber. This is what I finally decided on for my first re-build and I was pleased with the results.

The other head I hear a lot about it the P79(??) or something. The turbo head. The word is the chamber shape creates swirl and some sort of neato combustion voodo for more power. I've driven a car with this head and flat top pistons for about 9.0 compression and it made really good power.

I have heard a number of negatives about the E88 head. One is the valves are smaller (which of course could be changed) but also a lot of discussion of good (early) E88s and bad (later) E88s. I was never able to determine of to tell a good one from a bad one and basically wrote that head off as a bad risk.

The N47, never heard anything good about this head. It has round port exhaust with sheetmetal exhaust-flow-blockers. I think the emissions police really killed the design on this head.

Finally the coveted E31. Smallest chambers >> highest compression ratios. Come with smaller valves (again can be swapped for bigger ones) I have heard that intake/exhaust flow may not be that great (I've heard even a 'bad' E88 would flow better). I think I remember good things about the chamber shape, but I also hear they are more prone to cracking. Not really sure why but people really seem to like this head a lot - probably partially due to the earlier Z mystique. I believe just slapping one of these on an L28 will lead to very high compression ratios but if you put together the right combination of parts I am sure it would perform very well. (Heck, it's what I have on my car......)

But if you already have the N42 that's probably not a bad choice.

Scott IZCC# 149 72 240, Mt View CA

The reason for using the p79 or p90 (from a turbo) and beware of the P90A(hydrolic lifters is because the offer high swirl chambers (the engine gurus can explain the benefit more completely, I just know that this design of chamber helps minimize detonation. I would lean towards a P90 since a turbo application would likely be designed for higher exhaust capabilities as well. Side benefit is that the later model heads have hardened valve seats. Alot of this may sound vague. I'm not a an engine builder, just a humble researcher in quest of power!

I am currently looking for the final pieces to complete my 83 ZX turbo motor to be installed in my '72.

Alan Kirshbom - New Orleans, LA EBR #555, Deep South EB Club, '67/'77 in progress IZCC #2982, '72 240Z

Hello all, This is rather long post at the end, but I think the information will stimulate your thoughts. I have researched a lot of this information, and weeded out the misinformation. It is different, and worth considering. -Bob

All of them will match up. I used an N-42 head for a long time with the fuel injection notches and SU's on an L-28 with no problems. The only real advantage to welding is getting that perfect transition. I did that when I used the P-90A head,(see below).

I think it is the other way around. If you have the E-88 head, you have square ports. If you want to keep that header, I think what I am about to recommend would be great for you. (again, below........)

Ok, here is below!! As I said above, this is different, and I know some of you have thought about it, but not really had access to information on how it all works together. a lot of people may already know some of this, and so may you Kyle, but I will put it out anyway and not assume anything. (again, warning, this is long) First, just a small note on how to tell the earlier E-88 heads from the later E-88,(good vs bad). On the casting where it says E-88, the earlier, "good" ones have a much smaller lettering. If you have a earlier and later head next to each other, the later heads stamping of the letters E-88 are noticeably bigger,(but the same size as all other head castings, i e N-47, P-90, etc..). There are some smaller details, but that is the easiest way to tell. Of course, the valves in both heads are the smaller size. Now, on to the good stuff. I am finishing up the total rebuild of a motor for my initially short term, now long term project,(they are all that way, right? Mike?). Here is the quick specs for reference. A F-54 block,(the turbo block, slightly stronger), a P-90A head,(this is the hydraulic one), a diesel crank, 240 rods, 240SX pistons, net result, 3.1L stroker motor with a set of triple SK's. They are assembling the motor now, and will but it on the dyno soon to break it in, tune it, and get an idea of its power,(I don't trust dynos). I am going to put out all the information I have about the turbo heads for general info, and to help everyone understand why I chose them. They are excellent heads that are not as hard to get a hold of as everyone claims. Before I started anything on the motor, I did like many of you are doing now, or have done. I started lots of research. I have the How to Hod Rod and Race your Datsun book, so I had some starter ideas. But by far, my best resource was the internet. Now, as I am sure you know, you cannot take everything you see for gospel. But after seeing some things several times, and talking to many local experts, I sifted through the bull and have a good idea of what is right. I am sure many of you have been to Brian Little's web site where he discusses putting the L28 in the 240,(the purple datsun garage). He also has the P-79 mod page. In all my research, I found his pages to be the most accurate and the most informative. Well, his page got me interested in the P-79 head combo. He had mentioned something about the turbo head being better with the same design, but that was it. One of the local Z places has tons of used parts. I scrounged through his shelves of about 100 different heads. For combustion chamber, specifically the swirl chamber and its size, the P-79, the P-90, and the P-90A are identical. I have seen lots of areas that list a P-99 head and saying it is the hydraulic one, but in all my searching, I have yet to see one. I have the P-90A and it is a hydraulic head, so I think that is what people are referring to when they say P-99. Anyone who knows more about the P-99, please let me know. First, everything that Brian talks about doing to the P-79, you can do to the P-90. The P-90 is the same as the P-79, but the exhaust ports are square like the E-31, E-88 and N-42. Since I already had a header for the square ports, I too, like Kyle, wanted a head that would match, so I would not have to buy a new header. I knew a guy who had a two turbo motors and was willing to trade me. I traded a E-88 head and a 240 motor I had laying around for the turbo block and P-90A head,(yes, he got the better end of the deal, but he is a friend, and I am off loading all my spare parts). Oh, buyer beware, not all turbo motors have the P-90 or P-90A head. His second turbo motor had a N-42 head. It may have been switched, both the head and block, so check carefully. At this time, I didn't know it was a hydraulic head. I took it to the machine shop for them to clean. It was then that I found out it was hydraulic. For those of you who aren't familiar with how the hydraulics works, here it goes. Many of us have spent lots of time with the valve cover off, adjusting the valve lash. The hydraulic part of the head is the same part we used to adjust the lash with. The oil pressure pushes up on the "boss", exerting pressure on the follower,(under cam, over valve), keeping the follower in constant contact with the cam, eliminating lash, valve train noise and wear,(and a small, ok very small, gain in power). This is where the P-90A head shines in my opinion. Unless your car will be a weekend warrior who is only really driven above 4 grand, you will be picking a compromise cam. I was concerned with what was the max lift/ duration I could run with the hydraulics. Before I knew I had a hydraulic head to deal with, I was looking that the Motorsport auto 2003 and 2002 cam. They are about the max you want on a street driven car. I really had to hold back from my natural inclination to go hog wild. I am, after all, a Man, an no wimp would settle for less than Mongo cam!!! I talked with the tech reps at MA and this is how I narrowed to those two. Besides, any more lift and I was into custom springs, big bucks. Well, now armed with the info that I had a hydraulic head, I called the MA tech line again,(excellent resource). I told them my "situation". He told me he would check and call back. So now I knew I was doomed to granny cams and slow driving. He called back the next day, and said that I was fine with the two cams I chose, and gave me the maximums I could safely run with the hydraulics without fear. about .480 lift is max, any more and the oil pressure cannot hold the follower fully up. And anything longer than about 280 duration will have the same effect. I had settled on the 2003 cam before I knew this. I like to rev my motor, so it has .460 lift and about 270/280 duration, so I was close, but fine. The 2002 has a higher lift, like .475, but shorter duration. As I said above, the hydraulics, for your money, I think is the best head. You never will have to remove your valve cover and adjust valves again. As an added bonus, your head will last longer, because you are no longer slapping that cam down,(especially on high lift cams) on the poor little follower god knows how many times over 100k miles. But can you shave it? you ask. Yes, not as much as the P-90 and P-79, but 10 or 20 thousand is no problem. shim the towers, and put bigger lash pads. My engine builder has been putting big lash pads on L6 motors for years, even his 14.1 race motor and has no problem. What about compression ratio? Use the same tables as the P-79, they are the same. With my 89mm pistons, and diesel crank, and a slightly shaved head,(about 15 thousands), I am really close to 10.1. If I didn't shave the head at all, I am at 9.7-1. I wanted to run on pump gas, no matter what, so I limited myself to 10.1. Now, Kyle, if you stick with a stock 86mm bore, you will have a lower ratio. Look at the IZCC site or Z car club of Texas and look at the info that was put out by Jim Wolf at a Z car club meeting for combos vs compression ratios. I welcome any questions, because, even though I wrote a lot, I didn't put out all I learned about heads. -Bob PS- here is my thoughts on welding injection notches and port and polishing: Initially, I wasn't going to weld up the injection notches, but since I was going to do some minor clean up in the transition to the valve, I had them weld it and I used my dremel to smooth it back out. One word of advise for those of you who are looking at porting and polishing. One, you will go through a lot of sanding pads. Aluminum may be soft, but that glue that holds the sand on, isn't that strong. I used about 20 small drums, and 30 larger drums. It is also labor intensive. Bring a lot of patience with you. I was going to do a full port and polish job, but after really thinking about how I am going to drive, and talking extensively with my machinist, I changed my mind. As many of you know, as you smooth out the intake and exhaust runners, you lessen the turbulence of the fuel/air mixture, enabling a higher overall max flow. You also are enlarging the runners. This slows down the intake mixture speed,(larger volume, lower speed). So at lower rpm's, you will lose power,(there is a lot involved, but this is already too long). If you are planning on driving this car on a regular basis, I would strongly recommend just cleaning up the machining ridges and the transition area. Just my 15 dollars and some spare change. -Bob

Hi Kyle,  I just got back on-line and am behind the powe curve in this conversation.  Hope I'm not talking stupid here.  

Call Arizona Z Car (602) 844-9677   Dave sold me a cam package a while back that was a screamer.  Also, When Sean Hanson getys off his big navy boat in a few months, ask him what he uses for a cam.  He got 145 mph out of his SU's BEFORE he bolted on my new SU's w/Roadster needles! My crew is already working on a flowbench for the 260 Manifold.  It goes hand in hand with the triple manifold we are working on.  Hopefully, it will be done and Betas sent out before I get back from Bahrain. Initial testing reveals a 10-20% diffeence in the flow rates from cylinder to cylinder because of the runner design.  As we are casting 3XSU intakes anyway, recasting a conuterfeit 2X "stock" Nissan one that flows better should be a piece of cake.  We are also working on internal mods to the SU to get it to flow better.  More this summer...  The crossover tube work will not do anything, as it just equalizes out the pulses between pleniums.  I think your HP needs are within reason.  I regularly blew away 5.0 Mustangs in street racing with my 2k lb convertibles wL28, cam, headers, suppertrapp, ect...Scott 

Turbo it.  Call Turbo Tom, in Atlanta, Ga. 

If u have the engine out anyway, why not replace the water pump and oil pump? 
Bob 

Dean Byers 
76 570Z  Chevy 350/700R4 
Lockheed Martin Skunk Works 
Palmdale, Calif. 

Kyle, 
   
purpose of polishing rods is for stress relief, eliminating surface irregularities has definitly been proven to reduce chances of cracks developing starting at these points, value of it on a street engine is marginal at best, guess however probably worth the effort more than wasting your time on port-matching a street motor corked up with a  
muffler and this too has been proven for sure, let alone full porting work which should never be attempted by anyone inexperienced or without the guidance of experience. More harm than good will be the most likly out come.  If you have already had the experience of assemblying one engine succesfully, and already own the proper tools for the job, I say by all means do it yourself and save some money, any of the MAJOR name pro race engine builders will tell you in a heart be there really isn't too much magic in building any engines bottomend, the tricks and secrets are virtually always in the heads, oh by the way, on pistons; any of the well known aftermarket pistons are every bit as good as nissan's especially if all you really are going to do is street drive. I would use a flattop cast piston, flat top for power, cast because you run tighter bore tolerances with a cast piston, and they are cheaper, virtually all production cars for decades have used cast piston, only the very highest powered muscle cars had them and they are not good for daily atreet use because the bore has to have more clearance for thermal expansion as a result a looser bore promotes more oil consumption and more importantly is that on cold fire-up the pistons tend to "rock" in the bore (untill warmed up thoroughly ) and the skirts slap more and tend to collapse a little at a time untill the room for "rocking" is significant enough that the rings no longer ride up and down "square" in the bore and tend to wear "rounded off" hence loss of compression and more oil consumption, if you were around when the muscle cars of the sixties where in their "hey-day" I'm sure you remember that the REAL Hi-Po engines didn't really last much more than 30k-50k miles before they were really using some oil, this is the big reason why, and not as much from the abuse most of them did get. So stick with the cast pistons for a street use. Of course I may have overlooked that you may have said you may not bore the block? If this is the case, have you used a good DAIL bore gauge to check out of roundness, if less than .007" okay but then you might as well re-use the original pistons as well. Just to wrap up the piston issue, I, as well as about half a dozen of my friends have built numerous engines using cast pistons from Badger, Sterling and the like for "weekend warrior" drag cars that would run in 12's and 11's and these engines actually lasted for aleast 3 to 4 years!! Hard to believe isn't it? We had to use 'em because we couldn't afford "the right stuff" but we were stupid to realize it could'nt be done!! Anyhow as far as any engine parts go, if you use any of the well known aftermarket brands you shouldn't have any problems with compromised quality and probably save quit a bit of money. "Nissan Only"  mentality is questionable sometimes. 
  
my 2c based on years of experience & real facts 
                        
Darrell 
  

ps.  I seriously doubt you'll need new cam follower pivot studs or new valves & seats either. new springs however is not a bad idea though. 

Polishing the rods and crank reduces engine failure.  Rough ares on your rods get hot! To much heat in one particular area can lead to cracks and eventually a broken rod.  Your engine will definitely see RPM's over 6500.  This type of 
work helps the longevity factor. Also, as a rotating mass, the oil has less dragging effects and thus provides you more power.(If you put all the little tricks together correctly, you can one big trick). 

No problem. I run an L-28 bored .50mm., honed, flat-top pistons, polished rods and crank, and a bunch of goodies. Here is a suggestion if you have a little time and a little dough. 
a. Take the time and smooth out those rods. re-fit them w/9mm rod bolts. Leave no rough edges. (dremel tool and some sandpaper rolls) 
b. Use chromolly rings. Make sure they are gapped correctly. You may have to file a little. 
c. Have the assembly balanced as a unit. Harmonic balancer and bolt, crank, rods, pistons, flywheel, clutch plate, and bolts. (on the balancer you have that rubber insulator. Do you know I am referring to? You drill a hole were the belt goes big enough to drive a dowel pin all the way flush.(small pin). Thos is a precaution against the outer pulley section spinning. This could happen 
at high RPM's. 
d. Port match and polish that head. I have L-28 valves in it. Do not polish the manifold. its roughness helps fuel mixture,it provides turbulance crucial for good fuel mixture. If anything,rough it up a little.Unless you know 
exactly what you are doing, leave the bowl area alone! 
e. Make sure to in-line bore the block and the head(tower assembly) If you mill the head, you must use tower shims! 
f. as for cam, you will want something w/ 270-280 duration and 490-495 lift. new springs should be between 90 to 110 seat pressure. Cam dealer can give you specs. 
g. Remember, patience, planning, and methodically building your engine will ensure longevity and performance. Torque specs, are crucial. You want tolerances to be right on the money and equal. Plastigage will be your best 
friend. Measure and re-measure! 
h. I run my engine up to 7000 constantly. 2 yrs and it still run awesome. 

If you have any questions or need some prices, just drop a line. Oh by the way, on a street motor the highest you want to run is 10:1. The set- 
up you describing will yield just that. Mine is 10.1:1. Anything less than 93 octane, and she lets me know just how much she hates it. Good luck. 

Hi Kyle (everyone): 
A lot depends on your engine rebuilding approach or philosophy. 

A lot of guys I know only replace  " known bad parts" and leave everything else used in the engine.  Their idea of an engine rebuild is - replace rings and bearings, replace two badly burnt valves - re-assemble engine. 

Others rebuild engines and take the approach that everything needs to be replaced while the engine is apart - heck it easier to do it all at once and be done with it... 
So the engine gets: 

1. - new pistons
2. - new rings
3. - new bearings (crank and rods)
4. - new oil pump
5. - new water pump
6. - new rocker arms
7. - new valves & valve springs, retainers, lash pads etc.
8. - rocker arm adjustment struds
9. - new head bolts
10. - complete engine rebuild gasket kit
11. - new rod bolts
12. - new damper pully
13. - new timing chain, gears, tensioners & guides
14. - new clutch disk, throw-out bearing, and pressure plate
15. - spark plugs:-)
16. - hot tank block
17. - hone or rebore cylinders
18. - new freeze plugs
19. - new fan / alt. belts
20. - all fuel and vacume hoses under the hood& clamps
21. - engine, exhaust manifold and alumi. paints (laught but this alone can be 50 bucks)
22. - two oil changes with filters (one for break in and check - one for the next 6K miles)

Additionally all other items on the engine are rebuilt or replaced: 

1. - rebuilt altenator
2. - rebuilt starter
3. - rebuilt distributor
4. - new battary & new cables
5. - complete rebuild of carb.'s (you said carbs)
6. - re-balance engine - machine shop work
7. - new fues block
8. - new engine wiring harness underhood
9. - new fuel pump (if needed).
10. - rod out and rebuild the radiator (replace as needed)
11. - recharge A/C if needed...(R12 is very expensive now)

So bottom line is this:  If you go the route of the first case - you'll still spend more than the $2K you mention, but you may be close.... then just fix things as they wear out or break if needed. 

If you go the second route - it will cost you over $4,500.00 for a stock engine rebuild. This of course depends on where you buy your parts and if you want factory or aftermarket suppliers... It also depends on how much labor the shop you are using is going to charge you. (or if you do everything yourself). 

Add to the stock rebuild the modifications you are talking about and you could easily spend $6,500 to $7,500 on a modified L28.  By the way - anyone know what Rebello or Potter charge for a race engine now?? 

I am in the process of rebuilding the engine in Z Car #00020 now also.Believe me, I got a great deal on all the needed parts and the labor is all but free...I will have way over the $4,500.00 mentioned above by the time I'm done...  Being the car that it is - I admitt to being excessive - everything is being done 100% Factory Stock and original.... none the less there isn't a lot that I didn't also do when I rebuilt the L28 for my 72 Z...(actually I think it cost more)... 

For what its worth - and of course "to each his own".. 
Carl 

Carl Beck, 
Clearwater,FL 
IZCC #260 
69, 70, 72 & 72 DATSUN 240Z's

> I also see that I could mill the head in .020" increments to boost the compression a bit. Thoughts?

I would try to avoid doing this. I did this on my 280 engine that I rebuilt (N42/L28 w/ stock dished pistions) The primary reason I say this is that although it seems like a simple thing it ends up forcing you to do and buy a number of other farily expensive parts. First, the milling of the head itself was not cheap (I forgot how much but I was on a budget and this was one of the more costly things the machine shop did) Once you mill the head you must shim the cam towers to take up the slack in the timing chain. Seems simple but the damm shims (which look like plain old stamped sheetmetal) cost around $40 for every .20 you have to shim. Also, although it can be done, removing the cam towers and them trying to get them re-aligned again was no fun at all. I never got the cam to spin as freely as it did before I removed the towers. Next once you shim the cam towers the cam is farther away from the rocker arms and since I milled .060 it was enough to require me to buy another new set of thicker lash pads from Nissan Comp - anought $80 there. Then the final blow, I was putting a different (re-ground) cam in and that required another purchase of even thicker lash pads but now they were so thick I needed to buy yet another new set of valve springs w/ special deeper valve lash pad retainers. Oh yeah, did I mention that I already had the engine in tha car at this point so I had to pull the head again to install the new valve springs....???

Well, my series of blunders certainly soured me on this particular modification. My opinion is that the fewer things you change when it comes to valve train geometry the easier your life will be - while rebuilding your engine, and as you make further modifications down the road...

Scott IZCC #149 72 240, Mt View CA

First off, thanks Bob for all the info on head combos. Now, to add to the whole "head" choice thing: There are a number of Japanese imported N42 heads that don't have the injection notches cut into them. These have round intake and square exhaust ports. In all other respects they are identical to a regular N42 head.

John Coffey

Hi Scott / Kyle: Maybe this is the write-up that Scott refers to, its one of the better one's I've seen and fits with my experience. I am running the early E-88 on my L28 - with the larger valves, a bit of unshrouding and a bit of porting...nothing super or race car oriented - just a good three angle valve job..

by Jerry Jones:

For what it's worth;

It seems that the reoccurring question in this thread is " which is the best head", and ,as has been stated before, best is a relative term. What is best for full on race car is not always best for a street car or even for a streetable " hot rod". There are many factors involved and for a "blueprint" to be successful, all of the factors involved need to be considered. I have built a few "hot rods" for customers over the years, and have done all aspects of race engine preparation from porting and dyno work to machining my own dry sump pump. There are a few key considerations to consider when selecting or modifying any head:

COMPRESSION RATIO

The first thing one needs to consider when selecting a head is the fuel you are going to use. High compression is one step toward H/P but I'm not to sure a trip to the airport every week is very practical. I prefer to stay between around 8.5:1 and 9:1 for todays pump gas with a stock cam. Of course if you're going to run a "cam" then you can up the compression ratio as you kill off the dynamic compression ( but that's another story)

PORT CONFIGURATION

Port configuration is pretty good on all of the Z heads but the round port heads have a liner in the exhaust port that kills the flow.

QUENCH AREA/DESIGN

I'm not to sure how important this is on a street car but in a racing application it is critical, and this is one of the main differences ( next to compression ratio) in the Z head.

VALVE SIZES

This is not a critical consideration as all Z heads can be fitted with the larger 280Z seats and valves. This is relativly inexpensive and can be done by almost any machine shop.

PLUG LOCATION

Only important on initial engine consideration, and since the Z's are all the same or nearly so, enough said.

OTHER DESIGN CONSIDERATIONS.

This gets into things like valve shrouding; castings; seat and guide material; cam location/oiling ; and a few other thing I can't think of right now.

With the above taken into consideration I will give some Z head facts as I know them. I have to admit that my flow bench knowledge here is in terms of "relative" as opposed to the 6 months of research I did on my 2.2 235H/P NA Dodge Daytona. So I can't give any specific flow numbers here.

VALVE SIZE

The 240Z had a 1.65" intake and 1.3" exhaust. This valve size stayed the same till the 260Z when they went to a 1.38" exhaust ( same as the 280). The 280Z got a bigger 1.74" intake and the 1.38" exhaust. The valve sizes remained the same till the end of the L28 in '83.

E31 HEAD '70-71 240Z

This head has a 9:1 compression ratio. The quench area is the best of the Z heads with the exception of the P79. As stated before 280 valves are an easy installation and recommended. A note of caution here , however, if the 280 valves are used with a stock 240 or 260 bore ( they're the same) you will need to notch the block for the intakes. They JUST touch and make a hell of a noise ( take my word on this I know). If an oversize bore is used here then clearance is not a factor ( even a .010" overbore will do). This is considered by many to be the "best" head because of the "better" quench area and higher compression.

E88 HEAD '72-'74

The compression ratio is around 8.7:1 for all of these years. This is where things get confusing. There are three E88 heads, one for each of the three years. The 72 differs from the '73-'74 mostly in the quench area. This is significant as the '73-74 head has a raised quench area that increases chamber temperatures for improved combustion. Contrary to what you might think this is not good for H/P. These are the least desirable of the Z heads and the only way to tell them apart is to identify the combustion chamber. I think the '73-'74 head only differs in that the 260 has a larger exhaust valve. The '72 combustion chamber is similar to the E31 with the hemisphereical quench area a little deeper than the earlier head. Some IT competitors prefer the early E88, sighting that its valves are a little less shrouded than the E31. I've run both and saw no difference in ET's.

N42 HEAD '75-'76

This head is drilled for both carbureted and injected manifolds. It has the bigger valves and the same silicon/bronze seats as the earlier heads. The combustion chamber is very similar to the '72 E88 head ( including size/cc), and the 8.3:1 compression ratio is accomplished with dished pistons. For a straight bolt on this is arguably the best head by virtue if the reasonable combustion chamber and valve size ( remember this head will render an 8.7:1 ratio on a 240).

N47&P79 HEAD '77-'83

I lumped these together partly because I can never remember which year they changed, and they are probably the least desirable of the heads. The "round port" N47 head came out in '77, although I could swear that I've seen some early '77's with N42 heads. They had the same 8.3:1 compression ratio as the N42, and they were the first to have the hard intake seats and round port/lined exhaust. Unlike the earlier heads, flow bench tests yeild a 60% exhaust to intake figure, well below the 70% that most head porters consider to be acceptable. I have not done dyno work in this area but I've found most of the " rules of thumb" in the porting world are reasonably accurate. Of course there is always someone coming along changing the rules. The N47 had a real problem with cracks from the exhaust seat and I have taken to using the P79 head as a replacement. The one good thing about the P79 head is the quench area ( closed chamber). It is flat; large; and very near the piston. Unfortunately this is not enough to overcome the bad exhaust port. <BTW> The later of these heads have longer valves. I've seen this screw up more machinists!!

<IMHO> For street use the best all around head ( if I had to choose one) is the N42 head (as delivered). Reasonably equal performance can be had from the E31; E88('72); and N42 especially if the 280 valves are used. While this opinion may stir some debate, the differences would not be noticed by most drivers and could only be measured on a dyno.

I hope this helps.