Mark Maras
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Everything posted by Mark Maras
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Your original lug bolts look like the ones that came with my 71. It had a set of slotted alum. US Wheels. I remember that they were a minor PITA due to the tight fit in the wheel & the extra length.
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Afm Spring Adjustment - Bothersome Thoughts
Mark Maras replied to Zed Head's topic in Fuel Injection
There is no way you'd get close to 4500 under load with the same amount of fuel that is used free revving to 4500. When my fuel filter partially plugged, the engine would easily free rev to the redline but under load all it could muster was 45 mph in 2nd, 3rd & 4th gear. -
Afm Spring Adjustment - Bothersome Thoughts
Mark Maras replied to Zed Head's topic in Fuel Injection
Ditto, Thanks. -
If you drive a Z, there are 2 types of driving, normal & restrained. I think, after the "tune-up", you're supposed to resume restrained driving. Yeah right.
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Gee, Looking at this news thru rose colored glasses, maybe they'll learn how to build good tires. Ex. In the 1950s anything that came out of Japan was cheap & guaranteed to break soon, & yet a mere 10-15 years later they surprised everyone with the quality, design & ingenuity in the products that came to our shores. Thanks Mr. K How long it will take China, is anyones best guess. Mark
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For Those Of You Looking For Something "subtle"
Mark Maras replied to HaZmatt's topic in Internet Finds
It would be a fun car if all roads were straight. -
Way back in the late sixties we used to remove one of the two springs on the weights for weekend drag racing. You can also source lighter springs or stretch the springs slightly. Pretty crude by todays' standards but you asked for old school. Mark
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Trying To Mantain My Idle In 1000 Rpm But Not Possible
Mark Maras replied to Johnny wick's topic in Carburetor Central
I don't recall an unstable idle with my SUs. Why the 1000 rpm idle as a target. I assume it has something to do with the cam. How hot is the engine when the idle drops? From what you've described, it sounds like it may be temperature related, Are you sure the engine was at full temp. when you set the idle? -
Hi all Just got home from the cardio. breakfast & a great time with Jim (S30Driver) & Geoff ( RossiZ). Two beautiful Zs , two great people & the opportunity to talk shop. What fun. Thanks guys, let's do it again before Jim drives his Z to Arkansas. All are welcome. We'll let you know. Mark
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Correct Rpm At Idle And Choke Adjustment On 240Z
Mark Maras replied to Johnny wick's topic in Carburetor Central
Cam timing was my first thought also. We used to screw around with offset cam sprocket keys in V8s(drag racing). A few degrees can make a noticeable difference. Also I once installed a Toyota timing belt 1 tooth off. oops. Gotta love non interference engines.The engine had little bottom end power but at 3500 rpms & above it acted like it wanted to rev to 8000. I didn't try it. Check out the cam timing & eliminate that possibility. -
Sometimes the free play can be difficult to detect. If you disconnect the pedal & slave cylinder springs, the free play becomes quite obvious.
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Correct Rpm At Idle And Choke Adjustment On 240Z
Mark Maras replied to Johnny wick's topic in Carburetor Central
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
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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Yeah, Good luck on the 3 sec. run. I doubt they got the wheel spin calculated correctly.
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Carpartsmanual.com has a good selection of drawings. Look in the 240 engine section.
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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
