Can anyone give me some help with setting the timing for my 85 z-28?
I have a 305 stock with a Holley 650 4BBL and an Edelbrock performer nitrous kit. I know I'm supposed to retard it 2 degrees per 50 hp of nitrous, but I can't even get my timing as is. I tried unplugging the vac. advance on my dist. and pinching the line and the mark on the balancer is so far counterclockwise from the timing tab I don't know how much it's going to change it if I DO adjust it. The car runs fine so I thought the only thing wrong was something I'm doing.
I have a plain (non vac. advance) light, is that a problem? Or is there something else I'm not doing?
And excuse me for being an idiot, but how do I read the timing tab? Some people said the deep groove was 0* and someone else said that the tube on the right is 0*... and each little groove is 2*? It seems there isn't much room for adjustment because there's only 2 grooves on there, or do I need an aftermarket tab or tape?

 

sounds like the outter ring of your ballancer has sliped.

 

ok, I added some timing tape and it read about 40*BTDC... do I assume my ring slipped? I turn it back to about 30 and it gets rough.
So when all this is dais and done what SHOULD my timing be set at?

 

It sounds like your still off that is way to much timing for a stock car. It should be at no more than 32-34 total advance. The timing tape is probably not on right. just go off the 40 and retard accordingly to how much nitrous u want to spray. Also if you go more than a 100 shot i would recommend stepping down a heat range of spark plugs to be safe.

 

Could it be possible that my timing chain skipped a tooth?
Is the 32-34* WITH the vac. advance? I've always heard to have the timing at 8-12*
I did get a 1 step colder plug, if I DO spray the nitrous with it off a tooth how bad will that be for the motor? It seems like the distributor is making up for it (assuming that's what happened), would it be too hard on the engine with the valve timing being off?

 

That is with full advance you should about 8-10 intial timing. i dont think there is anything wrong with your timing chain. If it starts popping or bog then let out of it and readjust things somemore.

 

So with my vac. advance off and plugged optimum timing is 8-10* at idle? It's weird though because it runs best with the harmonic balancer mark at about 10 o' clock... so I figured that the tape was correct saying around 38-40* initial. The engine starts getting really boggy and chuggy when I bring it to anything lower than 30*.
Thanks for the help so far...

 

so are u saying at a idle it says it is at 38-40? Your balancer should have a deep groove going across it. Find that take some white out or something similar and use that for checking your timing. Do u have a timing tab on the timing cover?

 

At idle:

 

I'm surprised no one (sofakingdom usually) has asked this yet:

Which balancer are you using
which timing tab

If either one isn't the bone stock one from the old 305, then you've most likely got a problem.

The other silly one is- are you hooked up to the right plug?

 

6-3/4" balancer (stock)
and the stock timing tab
and yep, I'm on number one

 

Then your balancer ring has slipped
You can replace your balancer if you want. I'd be leery about using nitrous without having any idea what timing you're running.

 

I don't think the ring slipped because the piston is all the way at the top (i used a fiber-scope) when it's at zero. Bad chain?

 

Pop the cap off when you're at 0, make sure the rotor is pointing to the lead going to the number 1 cylinder.
I highly doubt the chain skipped, that's pretty rare. Although you're really running out of possibilities so...

 

Ok, my chain was stretched quite a bit, but hadn't jumped. I've been running it at 8-12* with no luck on either or anywhere in between...

 

well then my suggestion is to get a new timing chain and a new balancer, or at least a stock one from a 305 that still has a good ring on it.

 

I already put on the new chain and gears... that's how I knew the chain was stretched. And if the balancer had spun wouldn't the zero marks be off when I had the engine at TDC (looking into the cylinder with the scope)?