Mark Maras

The fuel pressure should be between 3-4 psi. It'll run fine between 2 1/2 and 4 1/2 psi. Leaky float valve, stuck float, hi float level, sticking piston are the obvious possibilities. A few questions; Have you balanced the carbs? Does the float operate freely in the hanging position and does it shut the fuel supply off when it's lifted. Check it by blowing into the inlet while lifting the float. Was the old float needle the same length as the new one? How well does the engine idle, accelerate and run? What color are the plugs?

Looks very good. I'd say it's been apart twice before judging by the staked nuts. Take a good look at the brass synchro rings. The pointy end of the teeth should come to a sharp edge rather than be rounded over.

It looks like it's popping a wheelie. While not really liking it there was something about it that tugged at me. When I held my right index finger in front of that gaping chasm behind the front wheel, a gorgeous car came into view.

I seem to remember someone using braided steel cable to clean the lines. He inserted the cable all the way thru the line, frayed one end of the cable. hooked a drill motor to the other end and with the drill motor running he slowly pulled the cable back thru the line. I've not tried it but it sounds like fun.

I've purchased a few window handle clip removal tools over the years. None of them worked as well as a cloth shop rag slipped behind the handle (knob in the upright position) and pulled down until it contacts the ends of the clip. Then pulling the rag side to side will grab the end of the clip and pull it off.

If you're using ATF, use 20wt. If you're using 20wt. use 30wt. The brand doesn't matter. Be sure to tell us of any changes.

Thicker oil will richen the fuel mixture under acceleration.

I want to know about the normal set of carbs you have. What's wrong with them?

Post #1 you mentioned "Rebello modified" carbs and you thought they had been bored out. Can you give us more information about the modification?

IMO, the engine stumbling under acceleration indicates a lean condition. I'd start with the basics. Fuel pressure and volume test. Check the float levels. Balance the carbs. New needles. If you really want to learn the finer details about SUs, The "Just SUs" DVD from ZTherapy is an excellent source but any early Z service manual has the the carb tuning procedure.

Rockauto.com an Excedy clutch kit is $112.00. I believe Cliff @siteunseen has an Excedy clutch in one of his Zs and likes it.

You mean mask enforcers being shot and killed by people who object to wearing masks? The next six months are going to be a rollercoaster ride. Hang on tight.

Probably the bottom of the tank but that could lead to a discussion about how many is permissible all the way to why the hell take any out. They're all glued down anyway. The PO of my 260 used 3/4" (no minus) crushed rock and rolled the tank around the yard for an hour or so.

My guess is nothing fuel delivery wise. But I wouldn't want a few nuts and bolts rolling around the bottom of my coated tank.

I saw a similar method a while back that consisted of a gas tank duck taped to the opening of a concrete mixer. That fellow used spare nuts and bolts (noting the quantities) for the abrasive material.

That's correct. The gap stays the same. A super cold plug has a very short center electrode and porcelain. The difference lies in how far the center electrode and porcelain extend past the threads into the combustion chamber.

Heck, you're all set. No damage to the engine. The hotter plug extends into the combustion chamber a bit farther is all.

@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?