djwarner

I know, I know - Weber DGVs are neither fish nor fowl, but the came with the car when I bought it. I've been reading in this forum how these carbs are for family sedans and taxicabs ever since. But to date no one has offered a free set of SU's and associated linkages, air cleaner, etc. I will have an interesting post about recent modifications in another posting.

I've had a continuing problem with the idle speed or mixture screws changing position over time despite the spring tension to hold them. Thinking back to the days when all cars had carbs, this was a common cause of deteriorating idle between tune ups. As polution controls became common, the idle mixture screw was set at the factory and locked in place with a non-removable cap. But these are impossible to find today. I envisioned making my own caps out of plastic when it occurred to me that a similar piece already exists in the form of electrical wire nuts with shrouds. I purchased some at Home Depot - 2 to 5 # 14 wire size. I punched out the spring locks from the back side with a 1/8" punch and trimmed the shroud to match the screw surrounding. My idle speed screw has a hex head instead of a knurled screw head, so I cut a slit in grabbing area to weaken it. Here is what I came up with:

My C drive ate itself recently causing me to rebuild my system. One thing I have not been not been able to restore is the ad (domain) blocking in IE11. I believe I learned how to do this from a post on this forum, but search of the three letter "ads" is not allowed. Does anyone remember how to do this? I have since upgraded to Windows 10 and unfortunately, I can't find any equivalent option for MS Edge.

As I stated above, my automatic was made 12/70 with an AT and an E31 head.

To be quite on honest, I got the info on the internet from someone who's credentials I was able to verify. Unfortunately that was in 2008 and it has long passed into the sea of forgotten references. The last thing I want to become is the "some guy on the interweb said...." So if someone can help with specifics, please speak up. A quick google search gave this reference: http://www.turbofast.com.au/racefuel13.html BTW if you read the labels of MSDS on the so called "octane boosters", you will find the chemicals l listed above. As for the info on how octane affects our engines, I learned this from a chemical engineer who worked for Shell Oil in their racing fuel group many years ago.

Acetone at the rate of 5 oz per 16 gallons will raise the octane rating about 3-4 points. Ping or knock is the explosion of the air/fuel mixture. Proper burning of fuel is just that, burning rather than exploding. So running a higher octane DOES NOT generate more power. More power comes from the ability to run higher compression ratios and the ability to advance the timing. Acetone, toluene and benzine are often added by the refinery to modify the octane of their blend. Their principle function is to slow down the flame front. So can you get away with middle grade and adding acetone to save a few bucks? Sure. I had a 2002 Infiniti Q45 that I ran that way for 47,000 miles with no problems what so ever. Modern fuels run leaner, so this may be a solution instead of retarding the timing. I just don't have any experience in smog testing.

There are two different methods for measuring octane. The '70's owner manual specified 95 octane. The method used back then gave higher ratings than we have today. Today's premium gas rated 91 or 93 is perfectly compatible with our engines. Now if you want to try middle grade gas and it knocks, you can add 5 ounces of acetone to add a couple octane points.

I had this problem with Felpro head gaskets. They put a simple flat rubber ring around the hole for oil port. This perhaps 1.5 thousandths thick. Better head gaskets have a brass ferrule there that is many times thicker and is crushed when the the head is torqued down.

Steve, thanks for the heads up. My early Z does not have the carb circuit, just the manifold circuit. After completing my engine overhaul, oil consumption has gone to zero, but I was still accumulating soot around the exhaust. So I turned my attention to my Weber DGV carbs. Turns out the idle jets are way too rich. I have been working with the techies at Redline, getting tons of help. The main guru there told me that I needed to re install the heating circuit. As he explained it, the carbs do not produce a vapor, but droplets of fuel. When a cold engine idles, the vacuum created chills the manifold. The droplets of fuel will "wet out" on the cold surface like the outside of a glass of iced tea. The main effect is to lean out the mixture. The choke is designed to help enrich the mixture to replace the fuel dropped on to the cold surface. After hearing this, I noticed the Cannon manifold adapters got very cold when idling. These adapters allow the downdraft DGVs to couple to the side draft intake manifolds. To complicate things more, the fiber isolaters normally between the manifolds and SUs blocks heat flow to the Cannon adapters as the engine warms. When I found the heating tubes blocked, I began to consider alternatives. The Cannon adapters have their own heating passages cast in, but there is no easy way to connect tubing to the cast bosses. I pulled out my IR thermometer and found the adapters were chilling about 30 degrees F as it idles. All that aside, I am in the middle of tuning the carbs with some interesting findings. I will also be converting the DGVs from a two barrel progressive carb into a two barrel synchronous operation. According to Redline, this will boost hp 10-15% most noticeably in the mid range throttle regimes where we live 90% of the time. Right now I'm waiting for jetting kits an linkages. I'll document my results in another thread.

I have the same problem. The fittings compress an o-ring to make the seal. The threaded mating surface is in the intake manifold. The fact that you cannot rotate the intake manifold on the tube indicates there is corrosion between the fitting and the tube. BTW I tried to pass water through the passage using rubber tubing and a funnel and it only passed a drop or two. Using a wire, there appears to a blockage at the front of the rear manifold. My bores cope shows a small hole that appears rusted shut. The parts manual shows a thermostat behind the rear manifold that is supposed to shut when hot. But I have no indication when it was adopted. Any information about the system would be appreciated.

My car was built within days of yours and also has an AT. My matching number engine has an E31 head. By now most heads have been converted to run on no-lead gas. Perhaps the head was exchanged for a finished E88 when if was rebuilt. AT Series I car are quite rare. What is you VIN number? ATs accounted for less than 10% of Z production and wasn't introduced until SN 8944. The last Series I according to Carl Beck's webpage was SN 20438. This would indicate less than 1150 ATs. With normal attrition and the fact that many ATs were converted to MTs, very few ATs remain. Through this forum we have been able to account for 22 units, yours would make #23.

Just as an aside, our cars were designed with dual independent braking systems from the start. So even with a failed brake line, the other side of the system should provide emergency braking. So unless you are trying to emulate Jeremy Clarkson, parking brake performance should be adequate.

Hi Careless, Heat shield should be gray, not yellow. Inverting the engine is not a problem. When I rebuilt my engine, I used the cork gasket. Having had poor luck in the past as you have had, I took time to ensure the oil pan flange was flattened around the bolt holes and laid a straight edge around the perimeter to eliminate any low spots. Lacking a large, flat surface to double check for flatness, I laid the pan on the engine block and probed with a feeler gauge. When you are ready to install the pan, oil the timing chain once more. Lay a small bead of sealant on the block and apply the gasket. Use a torque wrench to avoid warping the pan and re-torque several times as the gasket will slowly take a set as you tighten. When the torque wrench clicks without additional turning of the bolts, you have arrived. As for the high temp paint, is has to be heat cured. They mention you can cure it by warming the engine in a specific procedure, but my results were certainly not up to your standards. If you use it, try to bake it in an oven as recommended. Others have baked it in a gas barbeque. In either case, cure it off the engine.

Was that insect killer or repellant? Not a chemist but I doubt it would be permanent.

One quick check would be to verify the self-adjusting rear brakes are properly adjusted and stay adjusted. Many other cars adjusted drum brakes by applying the brakes while backing up. Our Z's have a different mechanism. They are adjusted by repeatedly applying the hand brake. Many of us never use the hand brake and the rears can go out of adjustment over time. Also, with the rarity of rear drums today, a mechanic's proficiency levels may be found wanting.

You have 40+ years of amateur mechanics working on your car adding, deleting, or replacing things. If this is the only head scratcher you find, you are doing much better than average.

I grounded mine to the body as you describe.

Sorry, all I cared about was sound operation. No beauty pics.

Just ground the black wires. That wire serves to complete the electronic circuit that does the timing.

I can't add directly to this thread as I'm still deep into understanding the myth and methodology of my Webers. However has anyone considered a path of adopting the older GM TBI systems like Patton did? http://www.pattonmachine.com/TBI-Main.htm

If you have a set of punches, they can easily be fabricated from gasket paper. I did this during my overhaul when the one included in my gasket set was damaged.

According to Carl Beck's website, http://www.zhome.com S/n 8944 built in 08/70 was the first car not to use the 2400 valve cover. It also marks the first AT car.

Here is a paint formula though they don't show any examples: http://www.xenonzcar.com/s30/enginepaint.html Unfortunately, modern cameras are quick to modify the colors sensed in our photographs. They can be swayed by dominant colors, typically the color of the engine bay. A professional photographer can accurately capture this color but finding an un-aged, clean sample is difficult if not impossible.

It is time to call Datsunparts LLC. They should be able to tell you what kind of rings and valve seals were installed. Lean on them to explain the oil burning.

Always set a clock by turning the hands past the current time and then back to the correct time. ie if the clock is 15 minutes late and reads 6:35 when the actual time is 6:50, advance the clock to about 7:15 and then back to 6:50.