Mark Maras

@jalexquijano If you're going to try the hotter plug in #4, I'd use a BP5ES not a BP5RES. The rest of your plugs are BP6ES. No need to throw a resister plug into the mix.

A Uni-Syn is a great tool for balancing SUs. I still have my 47 year old original one that I bought for my first adventure in tuning SUs. It still works great.

Those numbers are excellent. I remember going down this road in the past. Deja Vu all over again. I can't think of any other reason for the dark #4 plug than electrical and it has to be somewhere in the cap, rotor (unlikely), or the wire. As I recall you replaced the cap and rotor with a good brand along with many sets of plugs. The wires were fairly new and of good quality but I'd start looking at #4 wire connections, both ends and measure the resistance in all the wires to see if #4 is going bad before the others. Meanwhile how is your float project going?

Interesting. How many miles do you drive before a new plug in #4 starts to crap out when accelerating? "Back in the day" if we had one cylinder that loaded up a plug more than the others we would use a hotter plug. In your case you'd use a BPR5ES in that cylinder, but the problem with #4 is most likely an electrical or a problem that would show up in a compression test..

@jalexquijanoSitting here sipping my PineSol and Quinine I seem to remember previous trouble with one of those center plugs that I thought you cleared up with a new quality (Bosch?) cap and rotor. You already had new wires and plugs. Is this the same problem cylinder and problem that has come back or is it ongoing?

Smarter, not at all. Adding to Cliff's suggestions, I would throw in a quick compression test to rule out poor compression in #4. I'd also pull the cap with the wires intact and measure the amount of resistance in each circuit by touching one contact of an ohm meter to the spark plug end of a wire and the other contact to the corresponding contact inside the dist. cap. If the odd #4 plug isn't caused by poor compression it has to be electrical. I can't think of anything else. Oh, by the way, next time you're out for a spin and you encounter the misfire above 4500, pull the chokes on just a bit and see if the misfire changes. Same goes for lack of power when accelerating from a stop. If giving it more choke improves either situation the fuel mixture was too lean at that point in time and you richened the mixture with the chokes. If performance gets worse the mixture was too rich. Every time I experienced a high RPM miss it was the plugs. Try swapping them out with one of the better looking sets you have stashed and see if the miss goes away. How long ago did the miss above 4500 rpms start? Old plugs?

If the mixture is correct there's no problem with cold starts. I suspect those with cold start and or cold running problems may have the float levels set too low or the chokes aren't set up properly.

I haven't tried ACDelco friction modified myself but it is highly recommended for old Z transmissions. I'm curious if an oil change to a different product will quiet the bearing down if it's in the trans?

The first two refreshes were for a serious grind going from first to second and a a mild grind going from second to third. Two others were bearing noise only. Complete success on all of them. Here's a thought. The first trans Was for the snick when changing gears. The synchros I removed looked near pristine. I reused them later in another trans. The shotgun refresh fixed the original problem but when I used the old synchros (near pristine) in a later refresh they too fixed the shifting problem. WTF, said I. Skip to years later when there was a discussion here about gear oil. Some brands work much better, shifting wise and I'm assuming it could affect bearing noise too. I wonder if a gear oil change would improve things? @Zup highly recommends A/C Delco Friction Modified. I now wonder if my first trans with the shifting problem had really been fixed with a different gear oil. Back then I probably used a Kendall product.

I always used the shotgun approach on transmissions. Along with all new bearings, all new seals, all new synchros and check the prop shaft u-joints while it's out.

Same here. I had to remove a screwdriver from my keychain although all my keys were sharper. I don't know how the above idiots get away with it. I do worry about their mindset and how many there are.

I wish they'd take the dollars being spent on all these flyovers and put it to good use on the ground. Hazard pay, feeding the hungry, supporting small businesses, The list is endless.

The rumor last week was Dr. Fauci was to be fired. He's being marginalized and (IMO) will be gone soon. Just like everyone else who doesn't wholeheartedly agree with every oddball whim and crackpot idea that pops into our President's head.

Relocating the battery ground wire to a secure connection is a good idea but If the engine would turn over, the ground was good enough to complete the starter motor circuit. I'm going to assume that it should have started before the tune-up. That leads me to believe it is either parts related or an installation problem. I'm going to out on a limb here and ask you to replace your new condenser with your old one and try to start it.

Back to the beginning. Is this the first time you're firing an old engine or if it was running before the tune-up, where there any problems then?

If the sides of the rails are still in good shape I'd consider removing the rusted bottom section of the rails and weld the new rails to the original rail sides.

I agree. If you can master butt welding the thin sheet metal found on Zs you'll have little trouble with new frame rails. The exception being the overhead welding.

I wouldn't weld them on over rusty rails. I'd replace the old rails with new ones.

How about something simple like leaving the carb return springs off. I can verify that the engine will instantly rev up with no springs. How are you "starving the carbs of air"?

The line drawn between religions and cults is often a belief in God versus a belief in a charismatic leader. Too many people end up feasting on the menu and never get to the meal.

The fact that it revs fine with no load but has reduced power when under a load indicates a lean condition. Confirm fuel delivery with a pressure and volume test. Check all fuel filters and after that start on the carbs.

Pine Sol and Quinine is an appropriate name for a Covid-19 cooler.

I'm staying with the tried and true Quinine and Gin.

Not ideas, fantasies. Probably one of the greatest fantasies that have ever been. Like everything else he has or hasn't done.

All true. He's as good as Lewis Black. Nice to hear someone state what's in my mind.