Mark Maras

Advanced ignition timing can cause broken rings and in severe cases holed piston tops. The first symptom is engine knock when going uphill. The knock is caused by the fuel-air igniting in the combustion chamber while the piston is still rising. (BTC) I know little to nothing about the 123 system so I have a question. Does this system control ignition advance to individual cylinders or does it advance all six with one function? Another way of putting it is could the system provide too much advance to one cylinder and not the others?

Take a peek into #4 with a borescope before you tear it down.

I'd use the 2.5 psi - 4.5 psi pump for Weber DGVs.

Your choice as to which surfaces get the dressing. A thin coating is all you need. Any more than will result in dressing squeeze out. I've installed pumps with no dressing, just a bit of grease on the gaskets and had no leaks. No need to lube the pump.

I believe the bucking is caused by a lean mixture. Too rich would just result in a lack of power but not bucking. The float levels are the primary mixture adjustment. The mixture screws are the fine tune secondary adjustment. I'd pull the floats and check the float adjustment and or the fuel level. How many turns down are the mixture screws when it bucks?

What weight oil are you using in the SUs?

The retainer can be replaced without removing the head. Same procedure as changing valve seals without removing the head. One of the members will report on the brand and model # of the valve spring compressor that is used. I've got brain fade.

@siteunseenHappy Birthday, Cliff.

150 psi is better but it should be a little higher. Is there any valve noise (clatter or clicking) after the last valve adjustment? If not, I suspect the valve adj. is still too tight. I pull all the plugs during a compression test and hold the throttle wide open. After checking all the cylinders, recheck the first two again. They will usually be higher the second time around due to oil circulation.

Those compression #s should be 165 or above. Are you sure the valves are adjusted correctly? Just reread your first post. No specs on the cam? As in no lash adjustment specs?

So, the fuse blows at the first key stage. I'm assuming that is accessories. The next stage is on and the last stage is start. If that's correct, you've got a short circuit in one of the switched accessory circuits. Which fuse is the one that blows?

It's just a flesh wound.

Geoff, sorry to hear about Lillith. Couldn't open the pic file either. Can you give us a description of the damage? I have a lot of parts just waiting.

Nissan cam or aftermarket?

Come and listen to my story about a man named Jed A poor mountaineer but he had a brand new Zed And then one day he was drinkin' up some shine And said to himself I'm gonna make this car mine

Choke cable adjustment can be quite finicky. Hitting that sweet spot that gives one full choke and raises the nozzles all the way up usually takes a few tries before I'm satisfied.

Sure sounds too good to be true.

Here's a visual check. Pull the air filter and watch the carb butterflies while a friend pulls the choke all the way on with no throttle. The butterflies should open a bit near full choke. That increases the idle a bit. If the butterflies don't move either the chokes are not operating fully or the cold idle needs to be adjusted. The cold idle adjustment is done by bending a linkage rod. However, I doubt that the cold idle linkage needs adjusting but it's worth checking.

When dealing with gaskets that tend to move out of place during installation, tie the gasket to the pan using sewing thread thru each bolt hole. When the pan is in place and the bolts are started just break the threads and pull them loose

@zKars Perhaps my description was lacking. I didn't add 3 turns to the mixture screws. I adjusted them UP 1/2 turn. I ran 2 turns down at higher elevation. Back to 2 1/2 turns down at lower elevations. The only other adjustment I ever made was one frigid winter I adjusted the mixture screws down 1/2 turn more than usual because the engine ran better with a bit of choke. During that time the screws were at 3 turns down. Hope this clears up any misunderstanding.

My 4 screw SUs were set to 2 1/2 turns down at sea level. The only time I had to lean them out was around 5000' heading up to Mt. Hood Timberline Lodge. (6000') At that time (hot day) the engine developed a miss. I adjusted them to 2 turns down, which cleared up the miss, and then readjusted them back to 2 1/2 turns when I got down to around 3000'.

If the repro requires a lot of massaging you may end up with the same amount of time as sourcing an original that needed a bit of work and will have spent more money. While looking for a replacement, I'd try a stud welder and a torch to pull out as much of the outside layer as you can on the old one. You might find the original usable.

Excellent info. Thanks for sharing.

Are the needles to small, as in .090" instead of .100"? I don't recall any hwj 4 needles conversations in the past.

Many Z owners have successfully used 93-02 Kia Sportage weatherstrip. I don't know if it will on a 300 ZX tho. Others have reported using 94-01 Acura Integra, 93 Volvo 850, and 96 Maxima (all 4 doors.