12a_rx7

Ok, I finally read up on ignition timing. I decided to play with the timing on my car yesterday and i had a friend hold the gas pedal down at 4k rpm and i turned the distributer counterclock wise and set it to 20 degrees btdc for leading and 10 degrees btdc for trailing. I was curious on why at idle the timing reads approximately 2degrees atdc for leading and and 12 degrees atdc for trailing.


DID I DO THIS CORRECTLY????? Did I advance it or retard it?? the idle went down and I was reading that it would rise after advancing the timing.....just wanna make sure..
Thanks

12a_rx7

im just worried that I might break something

dj55b

iTrader: (2)

I have always done timing at idle not 4k. do it at idle and you should hear it run smoother.

legokcen

iTrader: (8)

Timing will advance at higher rpm's.

12a_rx7

I noticed that too, that's why i was curious on the timing marks while the engine was being reved, it seemed to be at 30 degrees BTDC at 4k rpm before i turned the distributor. The 4 timing marks on the racing beat pulley reads from left to right...10 ATDC, TDC, 10 BTDC,& 20 BTDC. So i had to turn the distributor counterclock wise to get it to the 20 BTDC, but according to the Haynes manual, Counterclock wise is to retard. And im just following jeff20B's recomendation of 20 BTDC for leading and 10 BTDC for trailing as written on the DLIDFIS write-up. I hope I did it correctly......

Kentetsu

Those settings are a good point to start, but you need to turn the dizzy clockwise to advance the timing.

12a_rx7

oh and im using the MSD direct fire trick from mazspeed...does this complicate things as far as correct reading from the timing light?


sorry for my noob questions but im just not sure....

vipernicus42

iTrader: (4)

Don't worry 4krpm is where you want to be. There are two mechanisms which change the timing as the revvs increase, the vacuum advance (the little pots on the side of the distributor) and the mechanical advance (two little ***** and springs inside the distributor).

As per Paul Yaw's website (www.yawpower.com) you set your total advance timing by doing it at 4,000rpm

Read this article (http://www.yawpower.com/pultime.html) it mostly talks about adding timing marks, but tell you how to time it as well.

Sounds like you did it right. As long as you're using a regular timing light and not an "advancing" timing light (where you use the same TDC mark, but tell the light to blink earlier or later to advance or retard) you're okay.

MSD (as long as it was working alright before, shouldn't make a difference. You're testing when the spark fires in comparison to the position of the e-shaft. How the spark comes to be isn't important as long as at some point it's triggered by the distributor (so that you can turn the distributor to adjust it)

Jon

REVHED

Sounds like you're previous setting was too advanced so you in fact retarded it. I'd personally run a bit more as 20* leading is the stock setting for total advance. 24-25* leading and 15-16* trailing.

12a_rx7

But i never touced the timing before. At idle (before i touched it) it read 0TDC for leading and 20 ATDC for trailing. When the engine was revved at 4000 rpm, it seemed to be at 30 degrees BTDC for leading so i turned the disributor counterclockwise to get it to 20 BTDC.....Did the direct fire advance it????

FCKing1995

iTrader: (3)

i dunno where the hell you guys are getting 20btdc and ****... my haynes manual says 0 leading +-2 degree and 20atdc trailing +-2 degree or something like that. i set mine just yesterday to those settings using my new timing light and it runs a lot smoother. still tryin to adjust my damn rich running carb (though it might not be helped cause its jetted pretty large)

FCKing1995

iTrader: (3)

ah, didnt see your post

REVHED

Those are the factory settings at idle. We're talking about total advance at 4000rpm.

REVHED

Did you disconnect the vacuum advance? Total advance should be set with the vacuum advance disconnected. Otherwise you'll be retarded at WOT.

vipernicus42

iTrader: (4)

Aye! I think Revhed's got it!

Says to do so in Paul Yaw's article IIRC. That's why I posted it.

Jon

12a_rx7

the vacuum advance has been disconnected ever since i removed the rats nest a year ago....the car doesnt seem to miss fire, i mean it never did before.I just want to get as much hp as possible without blowing the engine, and ignitiong timing is where i believe 10 or more horses are hidden correct?. I remembered the when I did turn the distributor clockwise just a little about half a cm the car started to sound louder and higher pitched and was going way ahead of the 30 BTDC mark, that scared the **** out of me so i turned it counterclockwise to get it to the 20BTDC( leading) setting. Back to my curiousity, after i set the timing to 20 BTDC for leading at 4,000 rpm,but at idle it reads roughly 5 ATDC. Does this mean it was advanced???

Thanks Revhead and vipernicus42 for your inputs on this.....I need your knowledge!!

Kentetsu

It might be worth your effort to reconnect the vacuum lines for your vacuum advance. This will improve driveability and gas mileage. Removing them does not increase HP, and there is really no reason to do so unless you have a turbo.

capt murph

So let me get this straight. The vaccuum advance actually RETARDS the timing when it is in operation.

So when vaccuum is present at idle, it is working to retard the timing. Then when the pedal is to the metal, the vacuum diminishes, and the timing advances, which helps provide better acceleration,( as opposed to no change in timing when pedal is floored).

Is this correct?

REVHED

No, it advances the timing at idle and partial throttle. There is also centrifugal advance which advances the timing with rpm.

When you set total advance at 4000rpm you need to simulate conditions at WOT so you disconnect the vacuum advance.

12a_rx7

will reconnecting my vacuum advance lines change the timing?

12a_rx7

ok i did some reading again and I came upon an article that says setting the timing in more degrees BTDC is advancing it, so I guess i was retarding it.




One more question....I back tracked what I did a few days ago and i remembered that I had the timing light clipped to trailing1 and i turned the distributor because i thought it was clipped on leading1.[revved at 4000 rpm]...was that a no no? I was thinking maybe thats why I had to turn it counterclockwise....

Kentetsu

Yeah, you want to use L1 to set the leading timing by the lead timing mark on the pulley. This is the main setting that you'll want to adjust.

You can go a step farther and set the trailing the same way, but you will use T1 and the adjustment for that will be at the vacuum can rather than by rotating the dizzy.

12a_rx7

ok one more question...

when setting the timing at full mechanical advance, do i leave the vacuum pots on the side of the distibutor open or do i plug it before i rev it at 4000 rpm???