71zman

Thanks NapaBill - I will look them up :classic: :classic: :classic:

I need to get my E31 head reground, hardened valve seats, guides etc. Any suggestions for a machinist who knows how to do these! I would prefer Southern California area but will UPS it somewhere else if the guy is good enough. Thanks

I actually like the shim theroy, if the cam assembly started out lower than specified, "mechanical settling" might account for the changes over time. Regardless, I bought the new gaskets yesterday and will start taking it apart. Luckily I have a couple of Z engines in the back yard that I can salvage a head from and get it reworked. Although I don't think I will go back to that same machinist. I will re-post when I find something.

Yes, I have been checking adjustment when the cam lobe is at the top. I am pretty expereinced at these motors, this is the 4th 240Z I have rebuilt, I have always done all the work myself. A little more of the story - I rebuilt this engine about 2 years ago and it never did run right - it always had a slight miss at low rpm's. I tinkered with it for about a year before giving up and taking it to a mechanic. I thought the problem was the carb's and timing because I upgraded this time to a petronix ignition and weber carbs Pierre's in Hawthorne CA told me that one of the valves was adjusted too tight and caused that cylinder to miss. He adjusted it and compression went back up but the engine did still not run right - still a slight miss at low rpm's. I drove the car for about another year and got to this point where it was running worse and worse. I suspect that maybe what happened is that when I rebuilt this engine, the machine shop replaced some of the valves - I wonder if they used the wrong valves that might be a little longer than the original 71?? Or maybe he did something wrong in the grind?? Could another possibility be that when he put the cam back in the head, it sits a little higher than it should creating a tolerance problem? One clue to this is that it is all exhaust valves in the middle of the head (2,3,4)???? When a valve burns, will it sit a little higher in the head?? Thanks for the replies - it is great to have nice folks who willing to help.

My 71 has been running really poor lately. Well, I took a compression test and WOW, no compression on 2,3 and 4 - no wonder. It appears that the exhaust valves on all three (2,3,4) are really tight. Even when I adjust the the screew all the way down, I cannot get a feeler gauge under it. All the other valves are all about right. Suggestions short of ripping the head off?

I would not give up on your T/S switch so easily (unless you have $$ to burn). They are relatively suimple devices (at least on the 240Z). I you take it apart, you will find out that 99% of the time, it is just corroded contacts inside the switch itself. (You get inside the switch by bending the tabs of the switch out and carefully opening so the springs don't fly out). Clean the contacts with an abrasive (> 500 grit paper will do, anything less will damage contacts) and then the secret is to lubricate the contacts with a conducting type electrical grease to avoid future oxidation. If you still have a problem, ask for the new one for XMAS. 71zman

Well you learn something every day although I can't quite visualize the drift spacer approach. What exactly does the drift and spacer look like? How do you get alignment in the vise? 71zman

Yep, I changed more U-Joints in Z's than I care to remember. . The tools required are: 1) a big vise (BIG) 2) a sledge hammer, 3) a socket set that you aren't too fond of.4) a punch or chisel So the process is: 1) Remove the half shafts. They are 14mm bolts, use a boxed end wrench so you don't strip the head. 2) Put the half shaft in the vise and secure so you can see the U-Joint. Next tap out all 4 retainer c-clips on the inside of the U-Joint cap 3) Again, with the shaft secured in a vise and the shaft side U-Joint going up/down, pound down on the u-joint to knock the bottom cap out. Turn the half shaft 180 deg and pound the U-Joint the other way knocking the opposite cap out. Repeat the process with the other part of the U-joint and flange. 4) Get new U-Joints out of box and take off caps on opposite sides. Fit both the caps on the outside of the shaft flange and set the middle part of the U-Joint in place. Put the whole assempbly in the vise (this is why you need a big one) and press fit the caps inward toward the middle part of the U-Joint. Be careful not to disrupt the needle bearings inside the cap. I usually set the middle part in the cap that is moving to hold the needle bearings in place. Also be careful to keep the caps going in straight so they don't bind. Once the caps are close take you socket set and find one that is about the size of the cap in diameter. Open the vise and put the socket between the cap and the shaft and close the vise again using the socket to seat the cap far enough in so you can see the C-clip ridge on the inside of the cap. Put the C-Clip in and repeat socket trick on other side. Do the same to the other half of the Ujoint. 5) Always replace both U-Joints at once 6) When replacing the shafts in the car, use the Emergency Brake to hold the shaft in place to put the final tightening on the bolts :classic: :classic: