Spark plug question

[oldschool90]

Got an 81 720 with the z22 engine in it. Was wondering if the spark plugs at each cylinder fired at the same time all the time, and if not, is there a way to do that? Im not used to the 2 plugs per cylinder thing quite yet. Thanks!

[lil89ram50]

search much?

[Braden]

search much?

help much????

[datzenmike]

:lol: don't listen to these guys. Yes they fire together at the same time. Take both #1 intake and exhaust side plug wires off and insert two old plugs. Lay on a grounded surface like the valve cover and crank motor. You should see both plugs spark. It is possible to blow a fuse and one side does not work. If so replace the first fuse on the left side of the fuse box.

[oldschool90]

help much????

 

Hypocrite. -1 to both you and the first guy.

[oldschool90]

:lol: don't listen to these guys. Yes they fire together at the same time. Take both #1 intake and exhaust side plug wires off and insert two old plugs. Lay on a grounded surface like the valve cover and crank motor. You should see both plugs spark. It is possible to blow a fuse and one side does not work. If so replace the first fuse on the left side of the fuse box.

 

Just wonderin. I was on here a few days ago SEARCHING (coughcough lil89ram50 coughcough), and I found a few things, but it was a little confusing. Some one said something about the exhaust side gets shut off after it reaches a certain temp or engine speed or something like that. So just wonderin if thats true or not

[datzenmike]

Some of the later Z24 engines had a vacuum switch the sensed full throttle (low vacuum) and would shut off the exhaust side to reduce engine noise. You need a special distributor and the vacuum switch. Will run just fine with all plugs working.

[lil89ram50]

sorry man didnt mean to be such a dick, but it seems to get asked on here all the time.

[datzenmike]

The 8 plug Z dizzy has a single module, (think matchbox) that has three wires. One is power from the ignition and the other two outputs are for two coils.

 

Some of the later ones have module with four wires including an added white one. This extra wire, when forced to a ground condition by a vacuum switch, will make the module stop firing the exhaust side plugs. Dual plug motors need less ignition advance because two plugs, and thus two points of ignition, have a shorter burn time. When the exhaust side plugs are disabled the module automatically increases the advance to compensate for single plug operation so there is no loss of power. Nissan states this single plug operation is to reduce engine 'noise' under heavy throttle operation. (whatever that means)