sstrickstein

So here is a conundrum. I did some research here and on 928 internationals site. Then I looked on the sticker on my hood and the WSM. My sticker says to set the timing to 20 degrees before tdc at 3000rpm. The manual says 30 degrees. Also the manual says idle at about 8 degrees. So I set it to 30 but the idle was to high. So I backed it off till the idle was right. Runs strong now. But two weird things. I had to make a mark on my balancer for 30 degrees as none was present. Thoughts? Will having the timing this way effect anything other than power. She seems to be running better. And why would the manual have the timing set higher than the flywheel has markings? Test drove her around the area and liked the new tune. Can't wait to see how it goes on the freeway.

jpitman2

I work on setting ignition timing on my 83 at the highest advance I can without getting any pinging under the highest load I can manage, on a hot day (even though its an auto). If just advancing the timing lifts the idle, close the idle screw until its back to the 750 +/-50 spec. In fact I believe the car will run cooler than it otherwise would if the timing was later than it could be, for the fuel. Even her 92 Miata improves noticeably by advancing it from 10D to 14D BTDC on std fuel. If we lifted the fuel to 98O we could advance more .
jp 83 Euro S AT 55k

j.kenzie@sbcglobal.net

I discovered the same positive effects on my 84. As per Greg Brown's advice, I pay the extra 15 cents per gallon for premium gas, just as a cushion.
Good luck,
Dave

upstate bob

This can be a can of worms unless approached rationally. The 6 degree at idle works on lots of cars
with computerized advance curves, all allowing for rpm and manifold pressure. Personally I don't like it.
The absolute best way is to do an actual reading at 3000+ rpm, under load, preferably on a dyno.
I dislike vaccum advance systems because they do a crappy job of compensating for manifold pressure.
A purely mechanical/centrifugal dizzy always worked best on my old VW bugs. -strong and peppy.
BTW, 30 degrees is a good ballpark advance at plus 3000 for most engines.

Fsharp9

Ok ! ...............On my 84 US spec is my sticker or my manual wrong . Underhood it says 20 before TDC my manual says 31 before TDC , I set it at 20

dzaprev

More timing with out pinging equals more power. That's why idle raises and you are not giving anymore fuel. Car is running more efficient .

sstrickstein

Exactly what I found. And to boot the flywheel didn't have marks at 30 BTDC. So I had to make a mark. All I can say is I set it to the manual and the car runs much better. I do however wonder about my emissions. I live in a county that tests. I wonder what this does. Not hard to rest though.

Fsharp9

I can see a very faint line equidistant from the 20 with no label, it looks factory but VERY faint and looks too straight to have been put there by accident at where 30 should be

Mrmerlin

be careful with too much advance you can burn the exhaust valves.
if you have doubts look at the exhaust manifold to see if they are glowing red,
if so it might be wise to lower advance a few degrees

Fsharp9

After more reading , Section 28 page 33 of the WSM says beginning with MY 1983 20 degrees before TDC at 3000 RPM is correct for US and Canada, sticker is correct

sstrickstein

I checked mine after setting the idle correctly. I think after that it's at 25 or so