EA82 spark timing puzzle

[el_freddo]

G’day all,

Looking over a 1986 EA82 touring wagon, 5spd manual, CARB.

Had an idle issue that is now sorted. What is confusing is that it runs far better with the timing set at 20° than the factory 8°. 

At the factory 8° it’s very sluggish and won’t build revs quickly, almost like driving in sand on a paved road. At 20° it’s a rocket and accelerates the way you’d expect it to - no pinging/detonation either.

So I’m baffled as to what’s going on with the timing on this EA82. Any insight is welcome!

I’d love to EJ it but it’s not my L series to mess with like that. 

Cheers 

Bennie

[SuspiciousPizza]

Perhaps the camshafts have been replaced with non-carb cams? Other than having a known carb cam to compare to, I don't know how you'd check this. Someone with more knowledge and experience than I may know.

Is there any vacuum leaks to the distributor/ is the vacuum advance operating properly?

Does it idle poorly at 8 degrees?

:]

[bushytails]

My guesses would be vacuum advance or mechanical advance aren't working, or you're setting it with vacuum advance connected or at too high of idle speed.  You should set the timing with the engine idling at normal speed (no more than, say, 700rpm) and with the vacuum advance hose disconnected.  After setting it at idle with vacuum advance disconnected, rev the engine up and verify timing advances with engine rpm, then apply vacuum to the pod on the dist using a hand pump or a manifold vacuum line and verify timing advances.

[88SubGL]

Just me personally, but I run the timing at whatever the engine like’s best. To me, the factory gives you a starting point. I’m sorry, I know that doesn’t answer your question. 

[el_freddo]

Vacuum advance works - tested with a hand vacuum pump watching the mechanism in the dizzy and the same when at idle. 

Timing done at idle with the vac advance disconnected and plugged. Idles well at 8° or 20° of timing. Just completely gutless when set at 8°, slowly pulls up the revs when past 3000rpm with the foot flat to the floor. When doing the same with timing at 20° it will happily keep pulling hard well beyond 4500rpm - and runs the way you’d expect it to. 

No vacuum leaks, checked over all of these and replaced several hoses as a result of vacuum leakage. 

It doesn’t ping or run hot. 

One thought I had was the centrifugal weights have an issue and it’s running purely off the vacuum advance - and the timing set at 20° counteracts the lack of centrifugal advance. 

Thanks for your thoughts on this fellas. 

Cheers 

Bennie

[bushytails]

Yes, the weights and such are the mechanical advance.  With the vacuum advance disconnected, slowly rev the engine up.  The timing should advance proportional to engine rpm, to about 3000rpm or so.  I don't have an advance curve for the ea82 handy, but it should just smoothly increase with rpm until it reaches a limit around 2-3k.

Another possibility is your mixture is way rich, and you're hiding it with timing.  Overly rich mixtures burn slower and need some extra timing to compensate. 

[el_freddo]

Hey bushytails, 

Thanks for that mini procedure for an easy check of the mechanical/centrifugal advance. I might have a tinker if I get the chance before it disappears. 

I don’t think the fuel mixture is rich as I changed the carb due to an idle issue. The replacement stock hitachi was known to run well and I haven’t seen anything different than expected. No black smoke indicating running a rich mixture and no running on that’s common with a rich mixture and engine shut down. 

Thanks for all of your thoughts on this. I think it can safely be put down to an issue with the mechanical/centrifugal advance. It’s interesting that it runs so well with static timing set at 20° BTDC. 

Cheers 

Bennie

[bushytails]

So you tested it and found the timing does not advance with increasing engine rpm? 

It's probably just stuck, and needs penetrating oil and poking at until it frees up.

[el_freddo]

The L went with its owner this morning, no time to tinker so couldn’t test the mechanical advance. Haven’t heard from them so all must be well enough… 

Cheers 

Bennie