Mark Maras

1200-1400, engine cold, full choke. I always adjusted my c-cables so that the lever, on the console, wouldn't quite bottom out in the slide, in the off position. The idea is to ensure the chokes are all the way off by giving them a bit of a push. Only a couple of times in a bitter cold spell did I have any starting difficulties. The chokes on SUs just deliver more fuel. As the engine warms, the fuel starts to burn more efficiently raising the RPMs.

Linkage or cable it doesn't matter-clean & lube everything from the pedal to the carbs. Try opening up the throttle manually on each carb, one at a time, with the engine off then do it again with the engine running. From closed throttle to wide open, they should operate ultra-smooth. No hard spots just spring pressure. & you might try loosening the springs for the engine off test. Be sure to hook them up before starting it up. VOE You should be able see or feel a difference & maybe isolate it to one carb or another. Luck Mark

ZTherapy does have the answer. The carb. bodies are fitted with sealed throttle shaft bearings. However there may be other things that would make a carb. a throw away. FastWoman's suggestion is a good one. I would look at the carb. linkage as well. Start by cleaning & lubing all linkage from the carbs. to the pedal. Also wondering if bad m. mounts could be allowing the engine to rock, changing the angle at the bell crank on the fire wall. It seems that you should be able to see, with another person inside the car, the difference that occurs when the engine is running.

I've seen the wrong TO bearing (too long) in a 71 Datsun pick-up run with no noise until the TO bearing wore a hole in the diaphram. He got better than 20 K miles out of that TO bearing. Surprisingly, it didn't weld itself.

Alas, It seems as though every previous Datsun owner has a sad " I wish I would have, tale. I guess that comes with the many fond memories.

Some shade tree advise. I would pull the cable from the trans., ensure the cable is fully inserted into the speedo., straighten the cable as much as possible, determine the proper rotation & hook the cable to a variable speed reversible drill motor. Go easy & don't max out the speedo. You will be able to run the speedo at varying speeds to see if it has any effect. Good luck & I hope it isn't the speedo.

Thanks Captain, I forgot about that. In the past I have blocked one wheel. I always had to jack up both sides so I could see my reference point on the drive shaft.

An easy way to find the gear ratio is, Put the rear of the car on stands, Mark a tire and the drive line with chalk or anything. Trans. in neut., e-brake off, slowly turn the tire exactly one revolution & count the drive shaft revolutions. In the case of a 3.34:1 the drive shaft will turn just a tiny bit past 3 1/2 turns.

Wow. That's about the best first car that I can think of. Do you still have it or is there a sad Datsun story? I remember the switch to 5 yr. financing. I wondered, at the time, how many cars would be toast before they were paid off.

I was a Chevy kid growing up, with the understanding that the mileage limit on any engine(domestic)& just about anything mechanical was around 125,000 miles. I traded my 69 SS 396 Chevelle in for my 71 Z. It was quite a change. I was skeptical about the quality in the beginning. During the 50s, anything from Japan was known as junk. It took a few years to sink in. But it turned out to be the best car I EVER bought. Ran it for better than 20 years as my DD & it was by far the most reliable car I've owned. Detroit could have been giving us quality all along, but they knew if their cars needed major repairs, the customer would buy a new one, & they did, every three years, religiously. Detroit has stubbornly refused to admit that "Quality is nothing more than basic honesty" People will respond to honesty.

Mechanic friend of mine checks valve leakage with the head off by tipping the head port side up. Any port that has a closed valve gets solvent poured down the port. If a valve is leaking, you'll see it fast in the c-chamber. At that point he pulls the offending valve or valves. If everything looks OK, he laps the valves & seats & checks again. I'd eliminate leaking valves as a reason for the low comp. before I tore the whole thing down. Unless you have the time, money & desire to do so.

Yeah, Good luck on the 3 sec. run. I doubt they got the wheel spin calculated correctly.

Carpartsmanual.com has a good selection of drawings. Look in the 240 engine section.

When thinking about all the bracing possibilities, I was reminded of a documentary about the Crystal Cave in Mexico. Massive gypsum crystals going all directions. The cave looks to be well braced. Mark

Damn, I can't shake this train if thought of tracking 3 dimensional movement. How about this one for the rear. Brackets bolted to the shock towers that hold kitty laser toys pointing up to a bull's eye target on the headliner. Throw in an observer or a Go-Pro & see if it was all worth it. Now to the front towers, No tracking, just reinforcing. What if, in addition to the standard cross brace there was a vert. support from the c-brace down & attached to the bottom of the tower & then triangulated up to the center of the c-brace as close to the v-cover as one wanted. The c-brace should be beefier & could be welded, bolted or pinned. From the upper tower brkts. possibly down to the lower rad. support & back to the fire-wall. One more c-brace or diag. back by the f-wall & I think it would do it. I'm thinking this could possibly elliminate some of the vert. movement in one shock tower when you run over a speed bump with one wheel. At least I think that is what is happening. Or am I just OCD? Mark

Geoff I believe these mech. pumps are basically the same as the old Chevy & Ford pumps. No return line back then. Nor do I think there is a pressure relief valve. Needle & seat will cut off fuel as long as the pressure is not too high. My only experience with elec. pumps are Lucas. If there is no clicking, you smack it with a small implement of destruction. Otherwise the clicking slows down as full pressure is reached. BTW, The stock fuel line set-up is coming with the SUs for the new build. Mark

I like Chris's idea of re-routing the lines direct to the carbs when going elec, but I think heat is more of an issue with FI than SUs. 20+ years as a DD w/ stock set-up, my 71 didn't experience any temperature related problems in the fuel system. Many Summer days over 100`f. As far as parasitic power loss from a mechanical pump, you'll find a lot more loss in the engine cooling fan. But that is another topic. Mark

This tale of Lillith kind of reminds me of breaking a wild horse. She has done her best to throw you many times, but you just climbed back on & wouldn't give up on her. Now that you know each other well, the major drama should be over. She has finally learned to trust you. Job Well Done, Congrats & above all ENJOY Mark

I don't think a blocked return line would cause fuel over-flow. If the fuel pressure is around 3 1/2 psi the needle & seat will shut it off. Also, if a blocked line was the problem, both carbs would be puking. The problem is in the rear carb float chamber. Check or re-check the following; float(does it?), float pivot assy.(NO binding), float tang adjustment(float bowl fuel level), needle & seat(does it seal), fuel pressure(elec. pump, bad regulator?). If I still couldn't figure it out I would pull the float cover off the front carb & carefully compare the two. Mark

Pull the float covers, again. While allowing the float to hang, blow into the fuel inlet fitting & gently lift the float. If the needle valve is sealing properly you won't get any air through it when the float is lifted. to keep bowl gaskets from Pringling, place them between pieces of waxed paper or plastic & keep them flat by placing them in a large book. Like pressing flowers.

Geoff The X bracing is the best & cheapest way to go. Also the possibility to make it multi-purpose as Carl suggested. Go for it. As a fabricator, I'll bet you could knock it out & have it installed in a couple of hours max. It would be great if you could do an accurate before & after either audibly or dimensionally. Maybe with the brace installed, one could belt a passenger to it to take measurements, tower to tower while cornering.

Many years ago during a Conference driver training course at PIR, I found the rear end in my stock 71 Z wanted to hop rather than slide in an oversteer situation. I installed a roll bar, for novice racing, mounted to the shock towers & the front side of the wheel wells (no x bracing). The change was quite remarkable. The rear slid, instead of hop, in a very controllable manner. I've always wondered how much deflection, in all directions, that simple addition eliminated. Many people shy away from roll-bars in a street machine but they are a great way to reinforce a uni-bdy car. Mark

Nice looking. Front & back clipped ala todays' fashion. 665 hp in a rear wheel drive GT is stupid. Why not make it a thousand hp or more. Just because you can, doesn't mean you should. I always loved the Z's balance of power & handling. "On track", hanging it out in a corner, one can steer a Z with the throttle. Good luck with 665 hp. Jensen will sell few of these cars. It will be neither affordable nor drivable for street use. Too bad. Mark

George Carlin is looking down & smiling.

Turn off the censure controls. We are all big girls & boys. We've all heard it & said it. You know, skinned knuckles, smashed fingers, bumped heads. The ZX thread was an interesting, if brief, study. Plenty of other club sites regularly use that kind of language. I found the CZCC members reaction to it entirely appropriate. Please let us control ourselves. We have been doing a good job of it so far IMO. Mark