Leon

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.

Plus, they are 15 minutes from where I work!

Wink-wink, nudge-nudge...

I was thinking the exact same thing as John, your timing is way too retarded. Advance your timing to 34 or so degrees with mechanical all in. Low speed cruise and transition will be slightly weak if the vac advance is broken or disconnected. BTW, 2.5" exhaust is definitely not too big. There is no such thing, take a look at the exhaust sticky. I'm running twin 2" pipes on my L24 without a hitch. That is 100% not your issue, unless someone stuffed a banana in your tailpipe.

I guess I'm lucky enough to have a few local places that stock SA helmets. You probably already have, but search around and see if you can find some local places. Racetracks, race-shops and circle-track equipment suppliers tend to stock this kind of stuff. If there are absolutely no places in your area, then I'd go to bike shops and try on M-type helmets. Sizing should be similar within product lines of each manufacturer, i.e. a Shoei M helmet should fit similar to a Shoei SA classified helmet.

The HEI is the cheap and proven solution. ZX modules are much more expensive and both options require some wiring work.

Yep, use KVL loop equations. You'll end up with 6 equations and 6 unknowns. You may be able to parse that down to 3 eq, 3 unk. Matrices would make quick work of the math.

This is how they all come, whether you get them from MSA or elsewhere. Holes are drilled "to fit".