Mark Maras

Halloween had passed.

Does the darkish white smoke dissipate or does it hang in the air? If it dissipates, it's likely steam. Oil smoke (bluish) tends to hang in the air for a while. That's why Charles recommends a compression test. You'll have more info when you pull the plugs.

Couldn't access the video. My guess is the "it" is a stumble or lag in the transition from cruise to acceleration. Normally one would increase the oil viscosity to eliminate the stumble if the carbs are tuned properly. Crazy idea but instead of weights attached to the piston, one could buy the appropriate sized (steel?) flat washers to sit under the springs. In theory, one could add weight and shim the springs at the same time. My gut feeling is increasing the weight of the pistons may help a lean stumble but it's going to lean the mixture in all RPMs.

I'd thought of doing something similar to this using a pencil, with graduated marks, in place of the stem and "twisty bits".

The wedge-shaped spokes are similar to other Porche wheels but in these, the narrow end of the spokes are on the rim side. All the others I've seen have the wide end of the spoke at the rim side.

Nether region porn.

I don't recall ever seeing those wheels. Couldn't find them using Google search. Any ID numbers or letters on them?

The only two explanations I can come up with are, an elephant sitting on the hood all winter long (doubtful) or the springs missed the tempering process during manufacturing. It will be interesting to see if the springs expand to original unsprung length when they're removed. Be sure to share the unsprung length with Vogtland.

A miss in three cylinders has to be in the cap, rotor, plug wires or plugs. It would seem that you've eliminated wires and plugs (NGK BP6ES?) from the list. Don't know what brand the cap and rotor are nor how old they are but I'd replace them with a quality brand. Nissan and Bosch are the two I'd investigate. Jalex in Panama cleared up a similar problem with Bosch parts.

Good advice above, However, I'm not a fan of pulling spark plugs from a hot aluminum head. I've done it many times successfully but I hate the feel of the plug coming out. @jalexquijano Have you pulled the plugs lately and compared #1,2,3 with 4,5,6 and how many turns down are you running on the mixture screws? Both the same? Deja Vu!

The only two reasons for switching to electric fans (IMO) are increased cooling at low or no speed and a slight horsepower gain. I think you're on the right track suspecting plugs. Especially because you said the problem went away after a quick Italian tune-up. What RPMs did it begin to misfire? Normal for fouled plugs is around 3500 and above. Is your engine still overheating in traffic jams? If so, I'd look into the electric fans. In extreme cases (hot weather and long waits) I just turned the engine off and when I did get moving slowly I kept the RPMs as low as I could. Fewer RPMs equals less heat generated. That said, I never had any percolation or vapor lock problems that would have prevented it from starting right away.

According to my notes and using the mount on both sides of the tail shaft housing for reference, your trans is a 77-79 wide ratio. 1st-3.321, 2nd-2.077, 3rd-1.308, 4th-1.00, 5th-.864

Ah, The Chevelle. It came with the Muncy (rock crusher) 4 speed. There were many things I liked about that car but in 1973 the gas crunch dropped the value of low mileage cars. I sold it in 74 for $800.00. Saw an identical one sell for $67,000 on Barrett-Jackson a few years ago. That said, after buying the Z, I was done with the Chevelle. I fell in love with sports cars at an early age. Thanks to the book "The Red Car", my insatiable mechanical curiosity, my sister's 58 MGA (which I used to hotwire and drive at the age of 15), it was only a matter of time before I ended up with a sports car.

If my memory is still working, that's the month. Definitely a Series 1. Dug out some old paperwork on "Hiro". April 1st, 1972. (I forgot it was April fools day.) I do remember driving by Gran Prix Motors in my 69 SS 396 Chevelle and seeing my soon to be stunning yellow Z. It was a spur of the moment decision. A short drive later and I deposited $15.00 with Joe Black to hold it until I got back from the bank with the sum of $3695.00.

My original Z is #08750. Series 1. Registered as a 71