djwarner

Leecheater, any update?

Actually there were 44 Z cars entered, and another 3 came but weren't entered. Which Z31 did you enter? I have photos of every car there.

OK that is the standard Nissan distributor for a 75 thru 78 280Z. Timing should be set to 7 degrees BTDC for a 75 or 76 non California engine. Otherwise 10 degrees BTDC. The only exception would be for a dual reluctor models ( automatic transmissions?). Sounds like a very good next step.

When you rev an engine, timing advances not retards. This is due to centrifugal advance. There is no Datsun spec to set timing to 18 before top dead center that I know of. I would not assume that a pinging engine set in advance of factory settings was set correctly by your shop. Most sources I have say timing should be set to 10 degrees BTDC not 18. If the engine was set up for racing with racing fuel, one could possibly get away with 18 BTDC, but not for street use. Retarding the setting to factory spec of 10 BTDC will do absolutely no harm to your engine and will improve your situation. While you are there, write down the model number on the distributor, the number is located on the metal casting on the aft side. from this we can determine the vacuum advance and centrifugal advance specs.

re-reading my last post I realized I wasn't very detailed when I talked about the timing changes over the life of the design. In reality, our engine timing varies with vacuum advance and centrifugal advance as well as when we twist the distributor during a tune-up. For the two dynamic advance have been adjusted over the years. For example, we normally set the distributor with the vacuum disconnected. When it is reconnected, at idle the timing changes. As we open the throttle the vacuum changes. How much and how fast the vacuum changes the timing is actually a mechanical program. Similarly, there is another mechanical program for the centrifugal advance which is determined by engine RPM. Over the life of these cars, programs have been tweaked several times as can be verified by the distributor part number changes over the various engine changes. Unfortunately, your particular engine configuration has probably never had the benefit of comprehensive analysis by a factory engineer who would design a custom distributor with unique programs for vacuum and centrifugal advance. This leave us twisting the distributor wondering what is enough. Now on top of this, you want to mess around with the fuel performance. As for the acetone, in the small percentages (4 ounces in 16 gallons) you aren't going to hurt your engine and it will boost your octane 3 or 4 points. If your engine is on the edge of running right, this may nudge it in the right direction. The goal for now seems to be eliminate the pinging during idle and normal steady state driving on pump gas. If you get that far, you may still experience pinging when lugging the engine or higher rpms. (vacuum and centrifugal advance issues). Mazda's Skyactive technology runs engines in this compression range and gets fantastic mileage to boot. But they use an engine computer to dynamically change the fuel/air mixture and timing. All that said, after adjusting the timing and perking up the fuel, it may still not be enough to eliminate the pinging or you may end up with a car that doesn't drive all that well. But you haven't done anything that can't be easily undone. Over the years, I've learned the unless you determine the cause of a problem, it is likely to be there after a major change. Only this time you are further into the boonies. What I am suggesting are logical steps to determine what doesn't work. Sort of like the bass fisherman quickly moving from area to area eliminating the areas where the fish aren't. This so he can spend time fishing where the fish are. In the long run, I would expect a carbureted, high compression engine with todays fuels will not be happy as a daily driver. That is why a 2mm head gasket may be in your future.

Do you know where your timing is set? Timing specs have changed for various models over the years. Easiest test would be to fill up with premium and add 4 ounces of acetone. Costs you almost nothing. Obviously your engine configuration does not exist in the manual's timing specs. If the acetone doesn't help, the next step would be to retard the timing 5 degrees. Both of these can be done before opening up the engine. BTW for grins and giggles, pull a plug and inspect the piston top for carbon build up. At 3K miles you shouldn't see any, but if you do, it could explain the super high compression ratio.

sponsored by the Sun Central Z Car Club. This club is the new combined Orlando/Tampa Z car club.

Time for Zfest in Tavares Oct 19-20 hope to see you there. http://suncentralzclub.com/events/all-about-zfest/

Another alternative would be to drop the compression ratio by using a 2mm Nismo head gasket.

Do you have any indications of detonation? Pinging? What is your timing set at? If you want to up your octane a couple of points, add 4 ounces of acetone to a tank full. Be aware there is little or no benefit to increasing this amount of acetone. For the record, many people think that high octane fuel has more energy, this is false. High octane impedes the speed of the flame front and resists dieseling. Detonation is when the A/F mixture explodes rather than burning. The intent is to burn rather than explode. Burning takes time. That is why the timing is set ahead of top dead center. It takes time to build the pressure. Pinging occurs when burning A/F reaches peak pressure before the piston reaches TDC. Pinging can be controlled by retarding the timing so the peak pressure comes later. Detonation is another matter and is a function of the compression, chamber temperature and chemical make up of the fuel. I'm no expert on E85 but is does have less energy per pound of fuel. Even though E85 is supposed to be 105 octane, a quick google search came up with a Corvette with 13.25/1 compression experiencing detonation on a dyno.

A few basics are called for. I bought a Harbor Freight compression test set that had a 12 inch hose on the gauge and another 12 inches of hose for each plug adapter. At the bottom of the plug adapter there should be a Schraeder valve (like what you find on the tire inflation valve). Mine had an open line going all the way to the gauge with no valve. This did two things, first, it drastically increased the cylinder volume reducing the effective compression ratio. Second, once the piston retracted, compressed air flowed out of the gauge and hose. I was reading the peak number and ignoring the fall off. A correct tester will give increasing readings with each compression stroke and stable values between each compression stroke. When the gauge stops increasing, you have your final value. A new compression tester from Sears demonstrated my compression numbers were not low, but in fact, higher than spec indicating serious carbon build-up in the combustion chamber. Just to minimize the load on your starter, I would remove all spark plugs while testing.

One point to remember is that the aluminum heads expand and contract with heat much more than the cast iron block. This requires the head gasket to accommodate the difference. At the same time, the metal surfaces have a roughness to ensure a good grasp on the gasket. Also our aluminum heads are subject to corrosion/erosion due to dissimilar metals. When I changed my head gasket this week, I did a careful inspection to look for breaches due to corrosion. Trapping coolant in the head gasket area with Alumi-Seal may accelerate the corrosion.

Actually, I'm running waterless coolant. Made the switch when I swapped my leaking brass radiator for an aluminum one. The waterless coolant won't boil in the hot spots of the engine after shutdown. Never pressurizes the cooling system even on the hottest days running the a/c.

If you are talking about going with the stock wheels, the recommended limit is based on the width of the tread. The tread width should be equal to the wheel width plus or minus a half inch. I have 6" rims on 14" wheels running 205/70R14 on a Series I 240Z at stock height. The overall diameter is ever so slightly larger than the OEM 175 HR 14 tires.

Hi Onion, I've been facing a similar problem, but oil rather than coolant. The previous owner got the car back on the road after 2-3 years and was fighting a coolant leak in the same spot. He said he eliminated it by re-torqueing the head bolts. This controlled the coolant leak but I am now consuming a quart of oil every 300 miles. It was a real head scratcher for a while. Replace the valve guide seals and tightened the belly pan bolts. The only evidence of oil leakage was a stain above the oil filter. It appeared so thin, I thought it was spillage when I set the valve clearance. After several high detergent oil changes hoping to free stuck oil control rings, I did a compression test. Not only was the compression uniform, it exceeded specs, suggesting carbon buildup in the combustion chamber or a shaved head from a re-build 10 years ago. I did a couple Seafoam treatments hoping to burn out the excess carbon. After a treatment, I drove the car just long enough to get everything warmed up. Parked the car and popped the hood. The damp spot was soaking wet and oil dripping down to the belly pan. Seemed that the highest oil pressure occurred at highway speeds before the oil finally thinned out. This is when oil pushed past the head gasket at the oil passage feeding the head. I am scheduled to pull the head tomorrow. One thing I've learned is that there have been three head gasket design variations by Nissan. It seemed they upped the head bolt torque requirements with each revision. Also some gasket designs required re-torqueing after the head gasket took a set after 1500 miles. So re-torqueing may bring you relief.

Savage42, From your earlier posts, I thought you were a snowbird wintering in Sarasota. I see now that Braille is there. Can I invite you to join our central Florida club, the SunCentral Z Club. We're having our annual get together next month. Woul like to meet you there. http://suncentralzclub.com/ https://www.facebook.com/SunCentralZClub

Xnke, went to the Deka/East Penn website and didn't find any Lithium batteries listed there, where did you find them at 1/3 to 1/2 the price?

Savage42, Living in FL all year round, my first question regards life in the tropics. In Sarasota, the typical 84 month battery lasts about 36 months. (Of course this means buying the best battery you can get at Walmart and getting a free replacement every 30 -36 months under their generous warranty program that resets the clock to zero with each new battery). From your description, track experience suggests a much better result than standard lead acid cells. But how well will it survive the sun in our Florida mall parking lots?

Had a similar problem when the car came out of the body shop after an accident. Blowing fuses. Turned out the body shop guy got over spray on the wiring for the side marker lights on one side. When the car was re-assemble for the last time, he reversed the ground and power leads to the light. Since the Datsun lighting systems include both a wire ground AND a chassis ground loop, reversing the leads at the light put the power lead to the chassis ground popping the fuse.

All of these lights are on the same fuse on the right side of the fuse panel. I had a similar problem in my '71 Series I, turned out to be corrosion on the back side of the fuse panel. I could measure 12V on both sides of the fuse, but only 7 volts at a center terminal of a bulb socket. Since it is affecting both the running lights and instruments lights, I would suspect the problem will be found inside the car. An easy place to measure the voltage at a socket is the service light under the hood. It is on the same fuse.

Gas filters are cheap. Go ahead and change it since it hasn't been changed since your troubles began.

I agree about the accuracy of the factory gauges. After buying my car, one of my checklist items was to replace the oil pressure sender and to calibrate the coolant temperature and oil pressure gauges. Found the coolant gauge was reading 25 degrees high but the oil pressure was right on after I set the internal voltage correctly.

I've been sitting here wondering the same thing. As I understand it, there is a pressure relief valve in the pump and a filter bypass valve for the filter. I was curious which one you were talking about in your prior post about cleaning one out. BTW took my '71 out on a cross country on a turnpike running the new AC, aluminum radiator and waterless coolant on a 94 degree day. Finally got the fan clutch to engage for the first time since buying the car last August. As I pulled off the turnpike, I noted the temperature up to 210 degrees and watched the oil pressure drift towards zero as I idled at 800 rpms at the stoplight. As the needle approached zero, the sender went open and the gauge dropped to the peg. I dropped the transmission into neutral and revved the engine up to 2000. The gauge promptly came off the peg and rose to 25-30 psi. The FSM check on oil pressure is 50+ psi at 2500 rpm warm. It does not give a minimum pressure reading or any other reading other than the pop off psi for the pressure relief valve.

BTW one of the functions of the fuel filter is to separate water and trap it in the filter. The original Datsun filters were clear plastic and you could observe the water trapped there. SOP was to disconnect the filter, blow in the reverse direction to expel the water and reconnect. Daddydonuts may very well be correct. Once the holding limit of the filter is reached, almost pure water flows to the carbs. Now, as to how much water remains in the tank, that's another matter.

The real problem with E85 is ethanol's propensity to absorb water. From what you described you started out with about 10% ethanol and then boosted it up to about 18% when you added the E85. If you are in an area that cools down to the dew point each night, you may have just created a water magnet. Heat is transferred in three different ways: Conduction, convection, and radiation. Ignoring radiation for the moment, your gas tank will cool down to the outside temperature by convection and conduction. Literally energetic molecules in your gas tank will transfer energy to the air or anything it touches that is cooler. Once the temperatures equalizes, the energy transfers stop. Radiation is a different animal. When you look at a light bulb, it glows orange/yellow as energetic photons are emitted from the surface of the filament. As temperature increases, the color changes more towards blue and then ultraviolet. As a body cools, the color turns to orange, red and then infrared. So even though you can't see a glow at room temperature, metal parts are still radiating energy in the infrared spectrum. As the radiation continues, additional heat is lost and the temperature of the gas tank falls below the outside air temperature. If the air has cooled to the dew point, dew will form on the metal surface. As it beads and runs into the gas, the ethanol mixes the water into the solution. Depending on how much water you have, the concentration being sucked up by the fuel pump might be quite strong. Water in gas doesn't burn very well - as your car has been telling you. The best way to remedy the problem would be to pull the bad gas out and put good gas in. This might be difficult to do. They sell additives for this to help mix and suspend the water so you can burn it out. This might be your short term solution.