Leon

Ok... read the article. Nothing in there about aerodynamics and its effects on cooling and lift, I didn't spot anything technical at all really. Just because someone did it, doesn't make it "right", no matter who that someone is. That would be like just taking someone's word for it instead of critically thinking about it for yourself. I suppose you can say that it works, if your definition of "works" is that it runs and drives on the street. However, this definition (or specification) is application specific. From what I see, you're building more of a track car. The one in the article is, for all intents and purposes, a show car. Maybe a definition of "works" for you would be that temps don't excessively climb during a 30min track session and front lift is as low as possible. Maybe not, the specifications are up to you. I'm simply making suggestions and giving some constructive criticism, take it for what it's worth. I would just advise you to read the Aero section of this forum as well as threads pertaining to venting and preventing excessive underhood air pressure. If you want some anecdotal evidence, then I'd ask you why is it that everyone else seeks to block the front end off, when building the Z for tracking or even land speed record runs? I'm not even sure what the problem was before, exactly. You said you don't want to boil your fluids. Is that what happened last time? Were you using fresh, high-temp brake fluid? What cooling problems did you have before that you're trying to relieve now? Sorry if this has been covered in your thread, but I don't have time to read through however-many pages of posts just to make sure that I didn't miss anything.

Couldn't have said it better myself! I will admit to enjoying mathematical exercises, though.

No kidding! Yeah, I noticed it when coming to a stop and accelerating from a stop. It was loud enough to present itself! Once I have my garage back, I can install new diff and tranny mounts along with my RT diff mount. That should get rid of most if not all driveline lash and make it even tighter. I'm really wanting to put in that ZX 5-speed and CLSD, but I'm hoping to go to the dyno first. Need to button up that Megajolt system, too. I've lost the nice wiring I purchased to wire it up during the house remodeling, so I'll have to go to the local electronics supply store and get some more shielded wiring and connectors. First order of business is to install that ZX fan already so that I can fit the VR sensor in there. Then I need to find a spot to mount the controller, make a relay bracket and mount the EDIS unit somewhere. After that, it's all wiring. There are always things to be done...

This is why I linked the Kameari web site in my previous post. This is straight from the manufacturer: 4mm equates to .157". 'Nuf said. Re-read the original question, you've misinterpreted it. The reason for the question is that with the head shaved .080", no cam shims, and the gear chain tensioner your cam timing will be retarded because of a shorter relative distance between cam and crank centerlines. OP was interested in using the stock cam sprocket (for whatever reason). In order to account for this, you must know how much the timing has been thrown off, knowing that the stock sprocket allows for 4 degree intervals of adjustment. I mathematically approximated the cam timing to be retarded by 4.6 crank degrees (please, do not rely on this number). Therefore, when using the second hole in the stock sprocket, the cam would be 0.6 degrees retarded or close to "straight up" when using a stock cam. This answers this original question, although I strongly recommend actually measuring the cam sprocket diameter and redoing the calc. As I and others have recommended, using a sprocket with more adjustment would be much more beneficial especially under the assumption that if you spend $800 on a chain tensioner, then you'd be fine with dropping some more for an adjustable sprocket. As the OP realized, using an adjustable sprocket and a degree wheel to actually degree the cam is a much better idea than approximating timing change due to machining and trying to use a stock sprocket to make up for it.

Then he either set it up wrong, or something went amiss. There is no reason that a properly working, properly regulated EFI pump should not be able to supply enough fuel at low pressure. We are talking physics here, not anecdotal evidence.

Excellent, I need to check this out. I'm tired of inhaling fumes when I want the window down.

"Volume" is not a restriction. I could see volume as a capacitance, but not resistance. A dual 2" pipe is close in area (and hence volume) to a single 3". I'd argue that dual 2" pipes are worse than a single 3" since there is more friction when using a smaller pipe. I did the twin 2" because I wanted the sound of twice pipes. It may seem counter-intuitive but that's how it works, if you follow what was presented in the sticky. I actually dyno'd my Z with a single 2.25" or 2.5" exhaust but have yet to dyno with the twice pipes. Unfortunately, those results are not going to be conclusive since I installed my header when I did the twice pipes.

This week has been good to the Z! Last Saturday, I removed the driver's door panel and went to town on adjusting the window frame, outer and inner door handles, and greasing everything up that needed greasing. I reassembled and then adjusted the door striker. Result? A smooth-moving and properly sealing window, less play in the handles and it takes just a slight push of the door to latch it. Awesome! The Z had always had a vibration that got worse at higher speed. I first attributed this to the 9-year-old tires (I think it's time for some R-S3s), but recently it's been getting worse. Even more recently, I started hearing clicking from my transmission tunnel as I slowed down, and sometimes when accelerating from a stop. It was noticeable at low speed and could happen whether the clutch was in or out, or the transmission in or out of gear. The frequency of the clicking was tied to road speed. This led me to investigate underneath the car. As I made my way to the driveshaft, I found that the nuts were loose! 3 of 4 were so loose I could spin them by hand. Good thing I checked it out now, before tossing a driveshaft on the freeway. I must've not tightened them enough initially and/or didn't tighten one of them at all. I got them as tight as I could, this time having my brother hold the passenger side wheel while I used the driver's side as leverage. I tightened by going under the car from the driver's side, putting a wrench on the nut, and using the wheel to tighten the nut. Turning the wheel will spin the driveshaft, as long as my brother was holding the other side (LSD still not installed...). Holy crap, what a difference! Much less driveline lash, vibration was gone (wooooo!), and the driving experience was totally changed! It reaffirmed me as to how one stupid thing can screw everything up. I didn't realize how much vibration I had before, but it's smooth on the freeway now. Take-offs are smoother as are shifts, I get much less clunking. As a side-effect, the interior makes way less noise and the tach bounces less (maybe coincidence?). I'm a happy camper.

Wha?

TimO, that is an awesomely beautiful Z! Those ITBs are sweet, custom? I'll have to check it out sometime!

Yes, it's clear he did something totally wrong. The EFI pumps are designed to flow at high pressures. As you go down in pressure on the pump curve, the flow rate will increase. There is no way you should run lean with a properly regulated EFI pump, pouring rich maybe but not lean.

That's the point of the gear tensioner, you don't need tower shims since the idler takes all the slack out. It's a matter of adjusting the cam to where you want it. http://www.kameariusa.com/L6_Twin_Idler_Gear.php

You can run the current EFI pump using a return line (equal in size to feed) and an inline pressure regulator.

Ok, we're talking about the OP's '76 Coupe. I have no idea why you're bringing up '74 specs. What I said is correct, ALL '76 Z-cars (whether 2+2, coupe, auto or manual) came with a 3.54 R200.

Whoops, looks like I'm off today. I need more sleep. Yes, crank degrees is the important number. As for your last statement, you've got that one backwards. Rocker arm wear patterns change because of shimming the cam towers, not milling the head. That's when you get into needing different lash pads, since cam-to-rocker distance changes.

9 cam degrees is 18 crank degrees. However, 9 degrees is the relevant number in this discussion, and that is correct. Correct, but only if you're referring to crank degrees. Cam degrees are more pertinent when talking about cam timing. OP, perform the calculation that I've laid out. That will let you know how much the cam will be retarded. You can then leave it retarded for some more top end, advance for more low end, or test both conditions and see what you like best. Don't skip teeth, there is not enough resolution there. An adjustable cam sprocket and a degree wheel is the better solution. I'm somewhat perplexed as to why an engine with a Kameari chain tensioner would have a stock cam sprocket. If I dropped that much dough to be able to take up slack in a timing chain, you bet I'd get an adjustable sprocket as well.

Incorrect. ALL of them had a 3.54 R200. The 3.9 R200 did not come to the US until the '80 ZX.

Nice find!

Take a look at the post date...

You can easily figure this out using the arc length forumla, S=R*theta, where S is the arc length, R is radius of cam sprocket and theta is cam retard (in radians). Your arc length would be the .080" and you'd have to measure the cam sprocket radius, in inches. Solve for theta: theta=S/R Plug in your numbers (I'll plug in an educated guess for R): theta=.080/2 theta=.040 rad Convert radians to degrees: theta=.040*(180/pi) theta=2.3deg Plug in your measured value for R, and that should get you close to what you should expect if you were to actually degree the cam before/after. Of course, nothing beats actually degreeing your cam.

Yes. Consult the BE section of the FSM. Download at xenons30.com

Online. I got it from here, it's the cheapest place I've found: http://www.texasaircooled.com/catalog/Weber-Carburetor-Syncrometer-SK-Type-1-30-kg-h.html

I don't want to drag this on either, hence why I posted the link. I'm assuming you haven't had a chance to really look it over. In a nutshell, the long pipe to the back of the car has nothing to do with scavenging, that's the job of the header and collector. You want the pipe to be as big as possible as to not create more losses, post collector. Therefore, the bigger the better. A smaller pipe will not make for less losses. You make a lot of assumptions about exhaust dynamics that are just not true (explained in sticky). I don't want to take this off track, and we both agree that this is not your problem. As far as your running issue goes, start simple. Check the charging system and make sure it kicks out the proper amount of voltage. Then check each ignition component for proper operation, checking timing is the last thing you'll do here. After that, and maybe a valve adjustment, go to fuel and carburation. Cam timing would have to be way advanced to cause such a seemingly huge hit on performance. Retarding the cam will shift your power curve to higher rpm. Also, make sure to check throttle linkage and the pedal stop.

FWIW, I don't think a 240Z front valence fits the early 260Z. I have an early 260Z front valence and a 240 shell, and I believe the holes don't line up, or something to that effect. Maybe a '73 240Z valence can bolt up, but I'm unsure of that.

One tip, don't get the Unisyn tool. The Weber STE SK syncrometer is much more user friendly.