JCan

This is great news! On my car the tapping noise continued to become quieter and quieter as time progressed Please keep us informed as to how your car runs after you tune it up. I think we are on to something here!

Lazeum. What you did looks great! When mine were done, Valley Head Service ensured that there was a slight rake (slope) from the edge to the center of the rocker arm. This ensured that the rocker arm touched the valve in the center. I think that what you did should work! Good luck with re-assembly. Be sure you warm up your engine and re-gap it warm. I have my fingers crossed!

LOL That was a long time ago!

Great rims! I'm going to send a picture to my brother! when he crashed his z they towed it away and miraculously next morning the rims were stolen from the car. I guess there is not a high demand for 4 bold rims these days... What are the odds? I guess great minds think alike? See you at JCCS. Jim

Leon. If you're coming out to the show, of course I'd drive the Z. It would be nice to meet you! I would really like to learn about the cam you are specifying (maybe you will make one for me also? ) and learn more about tractive effort. Regarding rims... you like the the old 14 inch rims? I have a set of 4 in my garage (see below pic). Back in the day, I powder coated them flat black then polished the outer edge of the rim (mounted the tire on the rear axle and idled the car in 2nd gear and used sandpapaer then a polish rag. The rims looked so nice when I was done. You could do the same to my rims, if you want them. I'll check to see if they are 6" wide or 7" wide. Regarding rubber for the tires, I suggest 195 65 14s for the front and 215 65 14 for the rears. 225 rims wont work on 6 inch wide rims, you need 7 inch wide rims for the rears to make that work.

Believe it or not, the car came with some really nice 14" rims. I would have polished them and kept them but today it is simple to purchase 17" rims and as a kid I always wanted to do that! Did you say you were going to come to long beach this year? That's not too far away from us, maybe we could meet at the show and you could show off your car?!

I just realized you were in France. if you have a file, you can grind the high points (edges) off your rocker arms. If you do so at a 5-10 degree angle you can watch the edge of the cut progress from the outside in toward the middle. I would stop once the cut edge passes the high point on the edges because the center of the arm is already parallel with the cam. Remember. we are doing this just so that you can gap your rocker arms properly. Gapping is a difficult process, I gaped mine after the engine was warm and was very careful to gap each rocker arm accurately. After gapping the engine, it was a bit quieter right after I completed gapping it, and continued to get more quiet as it broke in. Attached is a picture of what I am referring to. Good luck! Jim

Lazeum. you can grind them yourself it is a simple job using a fine grinding wheel. Valley head service did it by hand using medium-fine sand paper in a machine very similar to a power sander. The sand paper was about 2 inches wide. The goal is not to grind the rocker parallel with the lash pad but to grind it with a slight crown that is located approximately in the center of the lash pad.. This will force the rocker to hit the lash pad at one point somewhere in the middle. Break in of your engine will self grind the crown into a flat. My friends at Valley Head service in LA (http://www.valleyhead.com/) will grind your rocker arms for you. It shouldn't cost you too much. If money is tight, I suggest you grind the high point edges off of your rocker arms at a 10 degree angle and not even touch the center of the arm. I wish I had a picture of the arms after they ground mine. Tell me what you decide to do. Jim

Hello all... It is time for an update. Since my last post we connected the dash electrical and mechanical, and have installed the interior, cleaned up misc wiring in the engine compartment and connected up gas pump in rear of car. Interior: We used new plastic panels and vinyl from motorsport. The Vinyl went in okay however the plastic panels needed to be trimmed prior to installation. We purchased 50sq feet of be quiet sound deadening and used it on the outer door panels, roof, floor, interior hatch, and as many places we could find where thin metal could vibrate. next we went to home depot and purchased 4 linear feet of carpet and glued it into the front of the car and laid it on the rear deck with no fasteners. Weatherstripping. We purchased weather stripping kit from Motorsport. Everything worked out great except for the hatch and door openings. The wetherstriping at the door openings seems too hard! Wehave to slam the hatch and the doors to get them to close. i hear this is a common problem and may revisit this issue. Doors. I made a mistake and cleaned two drivers side door mechanisms so I had to go back to the plater. I took advanntage of this by removing all metal inside the door and having it all replated! Additionally I took the old stainless steel and polished it around the windows. Metal is great cause you can sand away years of neglect and it comes back looking great! Spare tire trim. I used a CNC machine (I had a membership at Maker Place in San diego) so I went a bit overboard... _____________________________________ All in all, the car has taken shape and we displayed it at the Motorsport show two weeks ago. Today we have 200 miles on the engine, and as expected first gear goes from 0 to 40MPH, and the car is not tremendously (due to gearing) fast off the line as designed. However after about 30mph, the car pulls pretty good.! Last picture is the car at the Motorsport show. We had a great time!

Lazeum. I am going to label your pictures 1-4 top left to bottom left then 5-8 top right through bottom right. Lets take a look at the first picture. Do you notice substantial wear at the edge of the lash pad and little wear on the center? This means that the rocker is riding on the ridges I spoke of instead of pushing at the center of the valve stem. It looks like the edges are being worn down rather quickly and by the time we look at image 5, it looks like the wear has sorted itself out. I suggest you file down the edges of the rocker arms to ensure you get contact at the center of the lash pad, then start your engine and warm up the car prior to re-gapping your rocker arms. I will tell you that now, the engine we are running sounds rather quiet. we have 200 miles on the motor and it is time to pull the valve cover and regap the valves. I can not guarantee that this will fix your problem, but it did fix mine. Best of luck! Jim

Leon. On the rocker arms, if the wear looks good on the cam side, you may not need to regrind that, although better safe then sorry. regrinding on the valve side is a must, it is simple to do, just grind away the edges so that the center has a slight crown to it. This ensures that the rocker arm will be flat with the cam and contact the valve at one point thus as you break in the motor, the rocker arm will self seat against the valve side and there will be no torque on the rocker arm. Jim PS We went to the motorsport show in LA this past weekend, car ran great! Even with all my fancy tricks to limit HP (high gear ratio + SU carbs) once the car hits 30mph, the car pulls really well!

Lazeum. This is one of those esoteric things that I learned the hard way! http://forums.hybridz.org/topic/110671-newly-rebuilt-engine-with-loud-tapping-noise-even-at-idle/ If the rocker arm contact point with the valve stem is not parallel with the rocker arm cam shaft contact point (is that a lash pad?) then gapping the valves will be almost impossible. When the rocker arm is parallel with the cam lobe then it is not parallel with the valve stem. When the engine runs the rocker arm with twist slightly and the engine will have a loud tapping sound proportional to the RPMs (if you go to the above blog I think I stored a short video clip) This happened on my car. Referring to the pictures on my previous post, look closely at the wear on the rocker arm on the valve stem side, you can see wear in the middle with no wear on the edges. When I used the new lash caps that were completely flat, the rocker arm contacted the lash cap on the edges of the cap not the middle. Long story short, after 2 weeks of removing the head, cam shaft, rocker arms over and over again, I finally found this issue. simple fix, I just ground the rocker arms so that they would contact the lash cap at only one place and it worked! Car is quiet and runs like it should! If you have questions, please call me - 858 204 9422

Wow! Great find! Some lessons learned from my rebuild. 1) be sure to grind your rocker arms prior to reassembly. I did not and had problems with the rocker arms not mating squarely with the lash caps and the cam. (see pictures) The old lash pads wore in the middle and not on the sides, the new lash pads do not have the indentation on the sides so an unground rocker arm does not sit properly on the cap. This caused me a lot of time to find out why my engine had a loud tapping sound. 2) if you are going to purchase an isky cam. I ended up with the Isky stage II cam 715148 (see picture below). With my SUs the car is too lopy and too loud. This summer I am going to swap back to the isky stage 1 cam. I suggest the stage 1 cam. 3) I used cast flat top pistons on my N42, 2.8L block. The crank/block combination pushes the pistons above deck by approx 0.025" (0.65mm). I purchased a custom copper head gasket which was 0.063" (1.6mm) which gave me a gap between the piston and head of 0.037". When I ran the stock head gasket, I believe the piston to head clearance was 0.025" which concerned me. My resultant compression ratio is 9.83 instead of 10.2 with the Felpro gasket. 4) Please find shims that are 0.040" and use two instead of four of the 0.020" shims. I had mine custom made. it was inexpensive. Thats all I have on the head rebuild. Good luck! Jim

There is a way to check to be sure your engine is timed properly. With the engine at 0degrees tdc there is a notch on the chain sprocket and a mark on the head. This notch is used to evaluate chain stretch. As Long as the line is in the middle of the v grove then your engine is timed correctly and your chain is okay. I think it is a good idea to look at this as a double check to ensure you assembled your motor correctly. Best of luck Jim I think it is a good habit to look at this alignment

Leon. WOW - CLSD plus 3.9:1 plus higher gear ratios from the 5 speed... very nice! Regarding your tail section and grill section. I had mine powder coated satin black. They turned out looking just like new. and the cost was rather inexpensive ~ $50. I'll show off a picture below. Jim

Leon... your going to sell it to me... right? (just kidding)

Interesting topic. Ive been reading about tractive effort and tractive resistance at: http://www.thecartech.com/subjects/auto_eng/Tractive%20Effort.htm . It is going to take me a couple days to absorb what I am reading. Basically we are optimizing the amount of Force (N) applied to the wheels and picking the optimum gear ratios to deliver this force on a level road taking into account rolling resistance air friction, and effective wheel diameter (rubber tires are lossy as compared to steel wheels). You know, I have always thought of the 240z as a variable displacement engine. IT seems to me that one could design an optimum gear ratios for fuel economy AND also take account the cars max performance. Therefore we could have one set of curves with the optimum RPM being low (2500 rpm) optimizing for economy and a traditional set of curves with higher RPM say 6000 RPM optimizing Force applied to the wheels, (tractive effort) Regarding Brian (my son). I think he has a level head and is rather deliberate with his actions. As he has completely reassembled each part of the car (with help from me of course) he has a lot of pride in it and doesn't want to damage it. Brian will only drive the car for the next two years, as when he goes away to college, the car will stay here (we do not allow our children automobiles at college). Once he graduates, I will put the car in his name and he will be free to upgrade it as he sees fit... Thanks for the introduction to great resources (Books) and this topic of Tractive effort. I am sure (over the next couple of months) to add this newfound information to my understanding of the car.

Vehicle dynamics prof? Leon, you are a sleeper! Send me your spreadsheet, maybe I could learn from it! Also, if you have a good book on vehicle dynamics I would appreciate the name as I might be able to thumb through it and get a better understanding of automobile engines etc. ( I did measure in general engineering in college and took the basic engineering courses, thermo, statics and strengths of materials etc). In the mean time, tractive effort curves... I'll look them up! My spreadsheets are rudimentary as I made them up in an effort to ensure the car I am building does NOT have tremendous HP from 0-60 (as after all I am handing it to my 16 year old son) yet allows me to add a few tweaks once he gets older to increase the fun factor! (notice the gear ratios are really high, I used SU carbs, the cam is a mild cam which destroys low end torque - yes the bad side is that after the engine hits 35mph, the car should be a rocket however brian's primary driving will be below 50 mpg (mostly streets). Jim

Leon, I am afraid I am going to be a bit long winded now... Apology in advance... Attached are two screen shots of an excel spreadsheet we assembled for the car we are building. Given torque as a function of RPM (what we expect to get out of our build) and the gear ratios w can assemble optimum shift points and can plot HP as a function of Speed (assuming I am racing the car). Please take a look at the spreadsheets --- Since I know my tire diameters, rear end gear ratio, and transmission ratio, and can look up what other people have measured (torque vs rpm) I can take a look at what the optimum shift points are for my car. The first spreadsheet shows (from right to left) RPM, Torque, HP, then left to right, the speed the car would be traveling if it were in 1st gear, 2nd gear, ... 5th gear by knowing the speed and Engine RPM then looking up the available HP (in the right). First thing, notice the knee in torque at 5500 RPM (I expect the engine I am building will not knee until 6000 rpm, but I am being conservative here). The loss in Torque causes a loss in horsepower at 6000 RPM. A wider torque curve would greatly improve overall HP. Your car has webbers ( a 6 pack right? ) Well your torque curve comes up much faster in the low end then mine does using SU carbs. You can model this here also.! Lastly, lets take a look at the last plot. In this plot I plotted the available HP as a function of RPM you can see the HP dips / each represents a shift point. In addition, I compared the car as is with a different rear end (one with 4.11:1 gear ratio). Notice the low end HP improvement! What happens if I swap out the stock rear end for one which has 4:11 gears. Notice we get 160HP at the tires at 20MPH in first gear (4:11 gears) instead of 35MPH at first gear (3.5:1). This little change should make a BIG difference to quarter mile and off the line times. Again, note your webbers have more torque at the low end then my SUs so your results may be difference. Which means, if I want my car go go faster, the easiest thing to do is to change gear ratios instead of farting around with trying to eek out another 5HP. This is a long winded way to say: - The L24/26/28 are magic motors and one thing they have is their ability to be perfectly balanced throughout all RPM. Take advantage of it! o balance your motor o understand how your modifications will effect torque - Take top down approach to building your car and understand how your car will respond to each modification you make o sometimes your best modification are gear ratios If you want a copy of my spreadsheet, send me an email and I'll forward it to you. James.Canyon@gmail.com

Leon. They are not going to balance your engine unless you ask for it. V8 engines can not be balanced throughout the rpm range and require a harmonic balancer, this pully sits on the front of the crankshaft and is offset and designed to make your engine run smooth at one RPM. on american engines I believe the RPM is maybe 4k? If you balance your L28 and they do a good job you will be amazed at how comfortable it is to run your engine to 7k+rpms (remember HP = torque * RPM, a flat torque curve out to 5k if you can get it yields what I consider to be as close to a variable displacement engine at 2krpm=x1HP The crank and flywheel assembly need to be done dynamically. Piston and rods are done statically. I checked the piston weights, rod weight (big side and small side) and they were accurate to 1 gram. (I have a digital cooking scale I "borrowed" from my wife when she was away Don't be afraid to assemble the bottom end yourself. It is easy and you can check clearances with plasti-gauge and some calipers (digital ones are really inexpensive now). If you want to talk, give me a call. 858 204 9422.