Ignition timing - can someone sense check me please?

[soldave]

I'll try to be as brief as I can here as I just want to confirm my thinking. When timing the car (25 degrees @3,500-4,000rpm) that,s what you're looking for on the timing light, right? I can set it at about that but my distributor adjustment is at its limit. Just wanted to check as someone has said that I should be doing 25 degrees plus the 7 degrees of static/idle retard, so giving me 32 degrees total. Only way I can seem to get at 3,500rpm is by setting the idle timing to around 13-14 degrees which seems way too high.

I think the advice is wrong but I just wanted a sense check from you knowledgeable people though as the 25 degrees was at the limit of distributor adjustment (all timing marks lining up).

Many thanks in advance.

Edited December 18, 2021 by soldave

[drdoom]

You're on the right track in thinking it's to be 25 deg distributor plus the static idle setting. It's very typical for engines to idle at around 10 deg or more, much less results in excess exhaust side heat due to late combustion. 

Cheers

[snowrx]

I would assume you could shift the aux pulley a tooth relative to the belt and change the range of timing available, if you need to go for more.  Don't know the Eclat specs, but I shoot for total advance  about 3000 rpm and then where the idle timing ends up depends on your distributor specs, advance mechanisms & condition.  My Turbo 910 doesn't seem to notice the difference between 10 and 13 FWIW.

[soldave]

12 minutes ago, drdoom said:

You're on the right track in thinking it's to be 25 deg distributor plus the static idle setting. It's very typical for engines to idle at around 10 deg or more, much less results in excess exhaust side heat due to late combustion. 

Cheers

Fair enough. So the total timing at 3,500rpm of around 32 degrees could be about right?

I do know the distributor in my Eclat right now isn't the original matching one - will sort that out at some point further down the road.

[drdoom]

Yes, Dave, 32 overall is right in the ballpark where fuel of decent grade is to be had. No sweat getting that in the UK, correct? In any case a stock '79 907 at 9.5 CR will be easily satisfied, octane wise.