Setting Timing Question 82 SC

[gazzerr]

Hey Guys,

I checked the timing on my 82 SC today after changing plugs. rotor and cap and it's a hair off. Let's say 4 degs BTDC. I wanted to set it to the 5 degs BTDC spec. I removed and plugged the retard hose that's on the port on the back of the dizzy with a golf tee. When I start the car it sits for a about 2 seconds then throttles up out of control and I have to switch it off. I thought perhaps I needed to plug the vac port on the distributor as well but no same result. If I plug the retard hose back in to the dizzy it's fine again and idles at 950. I assume it's sucking big time air with the hose detached so it has the same affect as moving the throttle. I suspect I have a major air leak somewhere? When I remove the oil cap I do get a drop in revs so I don't appear to have a significant leak. Any ideas? I know I must be doing something dumb.

Bad vac port on the dizzy?

Thanks G.

[mike635]

I just did this on my '81 SC, you need to adjust the idle down using the adjustment screw. The screw is on the left (drivers) side near the throttle body. I don't have a pic but if you look in this area with a flashlight you should be able to see it. The screw is pretty big and easy to adjust by hand.

[gazzerr]

Hi Mike,

Thanks no probs I know where it is. I've been adjusting my idle with the retard hose on the dizzy connected. Is that wrong?

[Bob Kontak]

This one puzzles me.

You are aware of which hose does what. Just in case, vac adv does nothing at idle. Retard does then it's function dies off quickly. Retard plugs into the port closest to the center of the engine.

This is my suggestion. Do nothing big right now until one of the wizards gives you trouble shooting thoughts.

Plug a right sized hose onto the retard port. One end hanging free. Start it and then go back to the engine and suck on the hose.

Confirm the issue relates to the vacuum retard.

I can't imagine what would make the engine rev up. Springs broken?

Also, how can it rev up when retard hose is plugged? You have not added an air leak.

[gazzerr]

Hey Bob yep this one is weird. I'm certain I have the right hoses in the right place. The car runs great (it flies) when it's warm and everything is connected. Once I pull the retard hose and plug it the engine goes into zombie race mode.

Funny I was going to do exactly as you suggested but I badly cut my left index finger cutting a piece of vac hose to do the test. So 1/2 a dozen stitches later my ego is wounded but I'll try once the ego is healed. .

I wonder if my dizzy is bad and vac on the retard port is masking an issue.

[Bob Kontak]

Originally Posted by gazzerr

I wonder if my dizzy is bad and vac on the retard port is masking an issue.

Check timing as it goes nutso.

That's all I got.

[mike635]

>Thanks no probs I know where it is. I've been adjusting my idle with the retard hose on the dizzy >connected. Is that wrong?

I'm far from an expert but here's my take - with the vacuum retard plugged in, the timing is retarded (as you'd expect) When this line is disconnected, the dizzy advances which results in an increased idle speed. On my car is runs up to about 2K but is stable. I adjust it down using the screw, then check the timing.

You probably know this already but it's important to verify the timing at 4K+ RPM to make sure yo're getting all the advance from the dizzy. I think our SC's are supposed to go to 25 degrees, mine does. Interestingly, there is no mark on my crank pully at 25 degrees so I had to make a careful measurement and put a white mark.

[gazzerr]

Thanks Mike,

I didn't let it run much past a rising 2.5K before I killed it so that makes sense. Perhaps I was just over cautious. I'll let it go next time and see where it actually peaks out. I just don't remember it doing this before. I'll test that the pod holds a vacuum too.

I'll check the 4K+ timing too. I'm assuming you had to readjust your idle speed again when you reconnected the retard hose?

[mike635]

I actually left the retard hose disconnected from the dizzy and plugged and then adjusted the idle down to 950 or so. Several people on the board have suggested this as a way to improve throttle response so I thought I'd experiment. My car definitely idles a little smoother with the retard line unplugged but not much change beyond that.

[T77911S]

set the idle for 950 with the vac hose connected.
set timing to either 5 BTDC or TDC. just for a reference.
remove vac hose and set idle for 950.
check timing again to see if and how much it advances.

I would also be curious to see how hi the RPM's go. it wont hurt it as long as you don't go over redline. after all Porsche wants timing checked at 6k, which I don't do, I just look for full advance.


If you have a hand vac pump, I nice tool to have, I would also pop the cap off and pull a vac on the dist while watching the timing plate inside, then remove the vac and see what happens.
you can also remove the cap and rotate the timing plate and see if it moves back to where it should be with no vacuum and that there is no play in it.

you do only have one vac port on the dist correct?
you should not have more than about 5 degrees retard which is not enough to change the RPM that much.

[gazzerr]

Thanks Sir,

I will try that and report back.

I have the 2 port vac block on the dist (82 SC) - the one with advance on the outside and retard on the inside near the fan shroud. I have the vac pump tool so I'll give it a whirl.

G.

[T77911S]

that's a relief. if you had only one port that would be leaving much to look at.

check to see if you have vacuum on the advance port at idle. you should NOT have vacuum on it.

[gazzerr]

Thanks will do! Appreciate the help as always.

[gazzerr]

Update:

I let the engine go with the retard hose disconnected and plugged and it ran up to 2500 and hovered there. I adjusted it back to 950 and set the timing. She's bang on now.

I reconnected the retard hose and reset the idle. The idle is definitely retarded with the host connected.

The retard and advance seem to work just fine. I tested with my vac pump and the I can see the dizzy doing it's thing so that seems fine.

It was just a case of me not being used to it revving up when the hose is disconnected. Thanks as always fellas.

G.