Timing question

opata · opata's Garage

Hello, I bought a timing light to time my 80sc. Which has power loss on acceleration....and other issues

I got it to idle at 950rpm. I checked the timing and the second mark the one on the right lined up perfectly with the mark on the engine. I brought the rpm up to 6000 and the mark moved left (ccw) about an inch. My question??? Should these marks eventually line up even at 6000rpm if the timing is correct. Sorry for a stupid question. But this is the first time I have tried to time a vehicle using a light. Also, I disconnected the vacuum hose that connects to the vacuum diaphragm on the side (sorry don't remember what its called) and the idle did nothing. I put my finger over the hole and nothing??? I was under the impression that if this was disconnected the engine would speed up?? Again thank you to all who have helped me get this car up and running! I cannot say how much I appreciate you help!!!

Walter_Middie · Walter_Middie's Garage

Hey Opata - Good job getting a timing light. I assume you have a standard timing light? Not a dial timing light?

The marks on the crankshaft pulley are at Top Dead Center (TDC or Z1) and the one to the right is 5 degrees Before Top Dead Center (BTDC).

The spec for a 1980 3.0 liter engine is:
5 degrees BTDC at 900 to 1000 RPM (so 950 is perfect)
15 to 20 degrees BTDC at 3000 RPM
19 to 25 degrees BTDC at 6000 RPM
With the vacuum hoses pugged.

Quote:

I got it to idle at 950rpm. I checked the timing and the second mark the one on the right lined up perfectly with the mark on the engine.

Perfect - that is your initial timing, and should be about 5 degrees BTDC. The mark on the right is the mark for 5 degrees BTDC.

Now the hard part. Every 1 mm is about 1 degrees on your crankshaft pulley (the pulley with the marks on it is the crankshaft pulley). So the mark that is lining up is 5 mm to the right of Z1 or 5 degrees BTDC. Now you want to check at 6000 RPM or the RPM where the marks stop moving. The spec says 19 to 25 degrees BTDC at 6000 RPM, so you want the crankshaft pulley to show 19 to 25 mm to the right of Z1 pointing straight up - just like at idle with the 5 degree mark, only farther to the right. Take a piece of chalk or finger nail polish or paint and make a mark on the pulley 25 mm to the right of Z1 (there may already be a mark on the pulley). This is the mark you want to line up at 6000 RPM.

There are some good youtube videos of how to set the timing - the type of car is not important, they all set the timing the same way. I'd spend some time watching those to help you learn what you are doing.

Ask more questions as you go if you don't understand - we all started somewhere.

Walter_Middie · Walter_Middie's Garage

Here's a good video:

YouTube - How to set your ignition timing

Walter_Middie · Walter_Middie's Garage

Quote:

I put my finger over the hole and nothing??? I was under the impression that if this was disconnected the engine would speed up??

You are correct - the idle speed should speed up. Are you putting your finger over the hose - not the tube on the vacuum canister on the dizzy? Do you have 2 vacuum hoses on your distributor? Maybe you are checking the wrong one?

ossiblue · 11-11-2009, 04:37 PM

Good info and advice from Walter. Just want to add that if you need to adjust your timing, the distributor rotor on the SC turns counter clockwise, so turning the body of the distributor clockwise will advance and counter clockwise will retard the timing.

opata · opata's Garage

Wow! Thank you so much for the information. The marks went to the left of BTDC when I took it to 6000. Thus I am assuming it is out of time by alot? I only have one vacuum hose on the distributor & I didn't plug it. I will next time. Won't have time tonight...bummer! I can't wait to get it running good! Thanks again for all the help!!! I'm sure you will hear from me soon as I ordered the CIS fuel pressure gauge from JCwhitney....Haven't done anything like that either!

opata · opata's Garage

Ok, I was able to sneek out! I am still a little confused. When I take the engine to 6000rpm the marks on the pulley should go to the right on the fan housing that has the TDC mark? Now the are going right??? Humm...I may wait until I get another reply. Dont want to screw anything up! Thanks!!

Walter_Middie · Walter_Middie's Garage

Use the 5 degree mark for idle - then forget about this mark. You want a new mark to come up at 6000 RPM. Yes, the 5 degree mark will move to the left. Forget it. You are now looking for the 25 degree mark that is 5 times farther to the right than the 5 degree mark. At 6000 RPM, the new 25 degree mark will come around and line up just like the 5 degree mark did at 950 RPM.

ossiblue · 11-11-2009, 05:21 PM

I think what's confusing you is the perceived movement of the pulley. Walter has laid it out for you.

If your timing is advancing, the 5 degree mark should move to the left of the housing mark.

You should see a new mark (that you made with paint or nail polish) approaching from the right of the housing mark as you increase rpm up to 6000.

Walter_Middie · Walter_Middie's Garage

opata · opata's Garage

I get it.

Makes since now.......I'll give it a go tomorrow. Thank you!!!!

opata · opata's Garage

Hello, got the timing set. It really wasn't that far off. So no difference in performance. I will now look toward vacuum leaks. I do have a question about the vacuum thing on the side of the distributor. The vacuum hose connected to it never has any vacuum?? I replaced it thinking it was cracked. It connects to back of the throttle body. No difference. Anyway, Ill research on how to find vacuum leaks. Thanks for your help!!!

fredmeister · fredmeister's Garage

Just as a note, you will gain maximum performance if you set total timing to around 30-32 degrees. Make sure your fuel is premium as you are removing the margin Porsche built in for pinging and detonation. Their 25-26 degree max timing is conservative.