LeonV

Now THAT is how you do a restoration! Nice work.

Make sure the valves are closed, chock the wheels, engage the hand brake and put the car in 1st.

You can find the information in Walter's spreadsheet: http://www.classiczcars.com/forums/showthread.php?34192-280ZX-Distributor-Advance-Curve-Reference

Yoshi, I'll have to take a look and see if I can dig up a heat shield. I can't guarantee it though, my garage is a mess! I can come by and have your car running the same day, we can improvise on a throttle return if you just need the car moving. I commute to Petaluma so I drive through SF everyday. I can stop by and give a few pointers or an extra hand sometime, just let me know if/when and we'll try to schedule it.

At this point, I would do a cold valve adjustment. Get it warm. Take off the valve cover again and check hot lash. After you've checked/adjusted the valves hot, you can perform the leakdown test. Find TDC on other cylinders by looking at the cam lobes.

Well, most people that run without vac advance do so when there are no provisions for a vac advance, e.g. when switching to triple Webers. In any case, load sensing spark advance (vac advance in this case) is a good thing. What you have going on sounds like a bad combination of fueling and spark timing. Sounds like you were leaning out at partial throttle and high rpm, while your spark timing did not advance enough to burn the leaner mixture on time. I don't run a vac advance on my triples because there isn't a provision for one, but my triples also run rich. A richer mixture will burn quicker than a lean one, thus the spark doesn't need to be as advanced in order to light-off the mix at the right time. However, clearly this is not good for efficiency. Sounds like your new carbs are set richer and you can test with vac advance connected. I think a properly working vacuum advance will cure your problem.

I'd say it's more like paying for the ice cream and having the ice cream man drop it as he hands it to you!

I think you said that popping occurs at 4500rpm and only partial throttle, correct? If this is the case, your distributor was probably not providing enough timing advance to light off the more dispersed, leaner mixture. I recommend swapping in a distributor with a functioning vacuum advance. Have you still not checked valve lash?

There isn't really a "stock" with the DGVs since they never came on the car, but were an aftermarket bolt-on. IMO, I wouldn't spend any money or even much time on them, I would either get round-tops or triples. Downdrafts don't make much sense on an inline engine. Good luck and enjoy the drive!

Weld the holes shut, grind down the weld, prep and paint.

A heim-jointed LCA is the better solution, with regard to LCA misalignment.

DGVs and SUs are both carbs, but that's just about where the similarities end. They operate with different principles. The SU is a variable venturi carb with just one jet, or circuit, to work with and uses a tapered needle within a moving piston to meter fuel correctly. The DGV is a fixed venturi, air-bleed carburetor and uses multiple jets/circuits to meter fuel. With that said, if they are currently jetted rich as the current owner postulates, then they may work fine at your altitude. In order to really tune the carbs, a wideband O2 sensor and gauge are highly recommended. Otherwise, you're just guessing and getting within the ballpark of where you want to be.

Thanks! I'm not 100% sure, but if I had to guess I'd say they're 0 offset (or very close to it). Next time I remove a wheel I'll have to look to see if it's in the casting somewhere.

A set pops up every once in a while, you just have to be patient!

:tapemouth

Get Panasports, you won't regret it! I am a bit biased though... 16X7 Panasports with 225/50-16 tires. Lowered by 1 to 1.5", no rubbing at all. Got them on Craigslist for $800 with tires included.

A stock P79 head on a flat-top L28 will not yield over 9:1 compression. It should be about 8.7:1 if I remember correctly. The exhaust ports are not restrictive as some like to proclaim, and will flow better than an E88. The 260Z E88 is not as desirable as the earlier E88 (yes, there are different castings of E88 heads) because the 260Z E88 is an open-chamber (poor squish) head. Also, if you do the math, the compression will not be over 10:1 but in the mid-9s. There are tons of threads on building up L-series engines, search around, especially on HybridZ. Spend the time to read the countless threads on the topic and you'll be rewarded with having that knowledge within yourself. Take a month or two to read and soak in information. Take a look at datsunzgarage.com. While some of the information is not 100% accurate, it's a good resource for basic Z-car modifications.

Welcome Bill, from another early 260Z owner!

The Z gods thank you! I smell a resto coming on. Just get those wheels off ASAP and send them to the crusher...

Sounds like lean-popping on decel, which is not a big deal. You'd have to adjust the mixture in order to get rid of it, and since you said the engine supposedly has extensive work done, we can't help further without more info. Post a video, and at the very least describe your modifications and the popping that you get in more detail.

I'm with them, fuel comes to mind for me, as well. Check all filters and replace as necessary. You can put in a fuel pressure gauge in-line for diagnostics.

It won't change how long you crank at all, not by even one-tenth of a second.

Can you please elaborate on the physics of this phenomenon? How are you going to increase vacuum at startup by extending intake length? This is a rhetorical question. Air horns will aid in decreasing entrance losses, but more importantly, they tune the powerband by varying intake length. This has no effect at startup. Your cold start issues most definitely lie elsewhere.

Sounds like a bad ground somewhere. When you turn on the headlights, you are activating a ground. This may be helping to ground another circuit that is involved in running the car (e.g. ignition, fuel pump, etc.).

Buy "How to Restore Your Datsun Z-car" by Wick Humble, it should be the perfect resource for you.