Ignition timing, bangin my head on a wall.

[LucasP]

I spent my day today timing magnetos to recip engines on a couple 100 series cessnas.  This got me thinking about the timing on my car... 87 sedan that has been webberized.  I'm very ashamed to say that I can time magnetos in my sleep but don't understand how to change the timing on my car.  I've read a bunch tonight about it tonight and I'm still in the dark.

 

Can we have a discussion on how to find or advance the timing? Obviously I know what timing marks are and how to rotate the disty.  I know how it all works, but I don't understand the process of using a timing light and whatnot.  Anybody have links to a FSM on the subject or want to run me through the process. 

 

I have no idea what my timing is at...

 

I know stock carbed ea82's speced 8 degrees dbtdc, but guys recommend 20 for webbers...

 

My car runs great, but today got me thinking and now I need to know more.  This whole thing is very frustrating for me. 

 

 

[tweety]

I'll assume you have a timing light. I'll give it a try in tuition.

 

The timing marks on yours should be on the flywheel at the rear of the engine behind a rubber plug (if the plug is still there.)

 

Connect up your timing light. Turn over your engine by hand until the marks on the flywheel are exposed and mark 8 degrees. With a weber I think 12 degrees would be enough not 20. If you want 12 then mark 12.

 

Use a 10mm spanner to loosen the clamp bolt at the bottom of the distributer but not too loose.

 

Start your engine. The light on the flywheel and turn the dizzy so your marks meet up with 12 degrees. Tighten the clamp bolt. Replace the rubber cover. That's it.

 

How'd I do guys?

[jono]

Pretty quick and got most main points ...

 

Connect up your timing light ? Tweety, this almost sounds like any car manual where they might just say 'remove' without saying how

 

most timing lights now have a delicate magnetic inductance ? pick up you gently as snap over the number 1 HT lead - some engines like to be different and use another cylinder. Some old school timing lights have a spring like adaptor to stick in between spark plug and its lead like my old Radio Shack/Tandy jobby ala 1981

 

Vac advance needs to be disconnected at dizzy and plugged up so extra air not screw up speed/mix etc

I check mine running before loosen off clamp screw on dizzy and check engine speed ` (800rpm) and always get it to that speed to alter/check timing.

 

Stick vac advance tube back on and see no difference in timing

 

think both EA81 and 82 the dist rotor turns anti clock when running, so by turn dist clock wise when clamp bolts (most EA82 have two clamp bolts) are loosened off, nudge it a smidge clockwise to advance, or anti to retard. You can also rev it a bit and watch to see if timing is advancing as revs increase - match the specs. I run 22 @ 800 with a RON (Oz RON anyway) 109 fuel - propane - on an EA82, sixteen on an EA81

Edited September 4, 2015 by jono

[tweety]

Yeh Ive noticed no difference when I replace the vac tube with timing.

[iluvdrt]

Don't confuse static timing with total timing, that was my issue for awhile. The 20 degrees is the total timing when the vacuum advances it. The 8 is the static timing with no vacuum advance.

 

Here is how I did mine and I have no issues now.

 

Keep the vacuum line installed on the distributor and loosen the distributor lock nut. Using an adjustable timing light, set the total timing to 20-24 degrees on the timing light. Rev the engine to apx 2500 RPMS and move the distributor until the 0 on the flywheel is aligned with the timing mark on the bell housing. Tighten down the distributor lock nut.

 

Who cares what the timing is at during idle, its when you're driving that timing becomes important.

 

I think at idle mine is around 4 degrees, but 21 degrees at advance.

 

Hope that helps.