Diseazd

Chach.....My guess is the previous owner did a conversion on your diff. The early cars had the half shafts coming forward slightly to the diff. The fix was a slightly longer (later Z) driveshaft, a 72 or later hanger and a 72 or later mustache bar ( not straight like the early cars) and then you would reverse the diff mount or use a 71 or later mount (which moved the diff back a couple inches). All of this moved the diff back, made your half shafts come straight to the diff and got rid of a vibration found in early Z cars. However, when this was done , the diff strap now was 2 inches or so forward on the diff.....it was obstructed by the two bolts. It could be put on, but was stretched tight. Look at your mustache bar. If it isn't straight, you probably have a converted early Z.

Zedy.....One more thought. I know you replaced the distributor with Steve's with no change, but my guess is you still used your distributor cap. Cracks in a distributor cap or rotor sometimes can be almost invisible. Have you tried a new cap and rotor? A hairline crack in the rotor or distributor cap can leak voltage at high RPM causing symptoms similar to yours. Just a thought. Guy

Certainly smells like a vacuum leak.....

first I need to get my fuel level in my carbs verified beyond a shadow of a doubt. As far as air leaking on the throttle shaft, I have to believe that Ztherapy carbs with their patented seals and bearings have eliminated this as a possibility... But a carb swap would be an easy way to verify this... I agree....and I would assume the floats were set correctly also.

Could it be a leak on the other side of the throttle plate (maybe shot throttle shaft bushings)? Zedy....If I were you, I think I would accept Steve's (tt) generous offer to try his SU's. This would eliminate the carbs as a source of your problem. It's only a 30 minute swap. Why not?

http://www.classiczcars.com/forums/showthread.php?42465-Proper-vacuum-readings&highlight= Zedy.....You can check for vacuum leaks (which would cause your problem) with the info that BLUE provided. I would just pull the exhaust and intake manifolds off and install new gaskets. It's a 1 1/2 hour job.

Zedy.....I'm coming in late on this thread so I hope this hasn't already been checked. Most popping through the exhaust in my experience has been caused by air being drawn into the intake or exhaust manifold. My green car had a popping because I had replaced the 3 studs in the downpipe with the wrong studs (from the head instead of the right ones ). They bottomed out before sealing the little downpipe gasket tightly. Took forever to find that one, but completely quiet now. Also, headers are notorious for poor matching of the flat area that snugs up to the intake/exhaust gasket. An intake or exhaust gasket leak will cause a popping......oxygen burns! I would start by checking your downpipe gasket (make sure it seals), followed by pulling the intake manifold and exhaust header and checking the intake/exhaust manifold for leaks (replace the gasket). All IMO......Good Luck Guy

PB......You will have to cut the tunnel and modify the console ( pain in the azz ). You can use the early 4 speed from your 70 with the L28 motor. Your early car has a short drive shaft and the half shafts are at an awkward angle. You should probably use your early 4 speed, a long driveshaft, a 72 or later mustache bar, 72 or later diff hanger and a 72 or later diff mount. This would be what I would do if I were you. IMO. Guy

The P79 head shaved, shimmed, rocker geometry centered and ready for installation. Note shims under cam towers.

My Christmas present from Brenda.....

Jonathan.....I always use Clevite main and insert bearings........just heard good things about them from people whom I respect. The pistons in all of my motors are flat top Nissan with Nissan rings (Total Seal are excellent also). Head gaskets are Nissan with Turbo head bolts from MSA. If you get a cam ground, Isky is tops IMO. It's important to use an oil with zinc......I use Valvoline Racing Oil VR1.......good insurance. Rocker arms can be shipped to Delta Cams to be reground.....$4.00 each.....they'll come back like new. If you have any other questions, just let me know. Good Luck. OZ......Turbo....Nice!

Happy New Year OZ! The engine is ready to assemble. The P79 head was shaved .080 inches and shimmed. SS swirl valves, Stage II Isky cam installed and I completed all of the rocker geometry work. It's a winter project and I haven't been pushed to finish the project since I really don't have a car to put it in (all 4 of my Z's have new engines in them already), but when I do finish it I'll pull an engine to install this mystery motor. Good hearing from you mate! Your engine sounds great. Guy

I'm surprised Dave ( z'sondabrain ) hasn't invented such a device......he could literally sell 500 of the bastards and they would be a cinch to manufacture! I'll take four Dave.

Get it up on a lift. Go up from the driver's side underneath. Find a suitable pry device to pry the back side of the lever where the cable attaches. I just did it.....no problem! It helps if someone puts downward pressure on the hood above the latch (relieves pressure on latch).

Upon initial start-up, keep the rpm's above 2000 for the first 20 minutes. When you take it for it's maiden ride, vary the rpm's and let the engine drag you down in your lower gears a number of times.

http://www.classiczcars.com/forums/showthread.php?42488-New-engine&highlight= Ted.....Sorry I came in late to your thread. Is this the engine you're trying to build? I haven't finished it yet, but it sounds like what you're trying to build. I can't wait to see how it runs. The P79 head is ready to be bolted on. Good Luck..........Guy

Dave....I agree with Jon Mortenson.....I've got two Stage II builds and two Stage III builds. Go with the Stage III cam. You'll be happy you did......you can really feel the difference between the two. Guy

Bruce Palmer drives one.

The 2nd picture is G/C coilovers. Welcome to the site. Guy

I recently bought the early M/C from my Nissan dealer.......try Courtesy in Texas if your local dealer can't find them. Price was in line.

Thanks Mike......

Ditto Mitchell.......I've got it in 3 out of 4 of my Z's......works perfect. I need 1 more.....Any chance Dave makes another batch?

There are some super motors and numbers being thrown out, some nice builds, but the thread is about the L24. Nobody builds better motors than Rebello and Coffey......I don't dispute that. All I'm saying is.......does anyone have a street driven Z with an L24 (NA and non turbo) that puts 200 h.p. To the rear wheels that will run on pump gas? I'd love to see how it could be done.......It would amaze me!

Sorry Julio......Didn't mean to sound arrogant......212 h.p. At the crank is different than at the rear wheels. Really nice numbers.

Show me your dyno run......I say B.S. To your claim of 212 h.p........I have 2 L28's with every option N.A. Available. The best we could get was 172 rear wheel h.p. Like I say....post your dyno sheet. Talk is easy....show me the money!