Fast240Z

I haven't gotten any replies lately, but I figure I'll try again. I just got the Z running again tonight (I wrecked my truck, and am in desperate need of a vehicle). Last weekend when I was driving my Z, it started sputtering, backfiring, and hesitating. The Z has been running rich, and it keeps backfiring out of the carburetors. The car is also making a knocking noise and backfiring, as well as running very rich. It sputters upon acceleration, and rattles. It's not backfiring out of the carburetors this time, but it is knocking. Could my carburetors be going bad? I have another set of carbs, and it wouldn't take me too long to switch them, but is this the cause?

Fast240Z

also, when putting my cam back in my head, I accidentally stripped out one of the bolt holes for the camshaft locating plates. I didn't think anything too serious about it, since the head bolts that go to the block go through the same plate. Should I worry about it, or is the head bolt going to hold it down well enough? I also left it in the head, because it held in there, but should I take it out?

theramz

You have all the symtoms of timing being way off. Check your points too.
Are you talking about the cam towers or the end plates?

Fast240Z

points should be good, I have a pertronix electronic points condenser system. the bolt broke off of the cam tower.

Fast240Z

when doing some research, I realized that the instructions I got from the BioPatent web site were wrong for setting the distributor rod in relation to timing, so when I get home today at 3, I'm going to drop the oil pump and set the rod right.

Now, I need to know how to set my timing correctly when using a timing gun. I understand how to use the gun, but not how to set the idle so that the mechanical advance doesn't kick in.

Haynes says:

1. Mark the appropriate notch on the crankshaft pulley with white chalk or paint (these are 5 degree marks, see Specifications for static timing).
2. Mark the pointer on the engine front cover also with white paint or chalk.
3. Disconnect the vacuum pipe (which runs from the vacuum capsule on the distributor) from its connection at the carburettor and plug the pipe.
4. Connect a stroboscope in accordance with the maker's instructions (usually interposed between #1 spark plug and HT lead).
5. Start the engine (which should previously have been run to normal operating temperature) and let it idle slowly (see recommended speeds in Specifications) ohterwise the mechanical advance mechanism will operate and give a false igniton timing.
6. Point the stroboscope at the ignition timing marks when they wil appear stationary and if the ignition timing is correct, in alignment. If the marks are not in alignment, loosen the distributor clamp plate screw and turn the distributor.
7. Switch off the igniton, tighten the distrubutor clamp plate screw and remove the stroboscope.

So, my question is this: my Z has no emission controls anymore (with the exception of the anti-backfire valve). According to Haynes, they say that the static timing should be at 17 degrees @ 650 rpms. I have no idea how to drop my idle down that low. I can loosen the fast idle screw, and it will drop the idle, but if I go more than 800 rpms, it tries to die. So, how would I set the idle lower so that the mechanical advance kicks in?

Last question: What do the notches on the crankshaft pulley denote? I know that they are 5 degrees apart, but which one is zero?

theramz

What you have is a tuning mess. This occurs after a dismantiling of the engine and components. Youi will have to tune the hole car. Set your timing at the fast idle to the 10 degree advance mark. See if it will idle down a little. Check for vacuum leaks and adjust the carbs. Go through this again to get the fine tune. If you need help on the carbs, pm me and I will help you throuh it.