390SE ignition timing map - 56 degrees MUST be too much!!

[ed_crouch]

Hi all,

One for the engine gurus:

A spreadsheet I found on t'interweb has suggested that I might want to be running a total of 56 degrees total advance at light throttle, high RPM!

This seems like a hell of a lot for the old Rover engine. Other sources say 36 degs, all in by 3500 - 4000 RPM from 8BTDC at idle, plus 6 degrees vac advance coming in as the load falls off at all RPMs. This sounds more like it!

Does anyone out there have any firm opinions on what the advance figures should be?

Here's my get-it-going map. I will be upping the advance in the bottom right corner of the map, but Im not driving it through that part of the map yet!!



Any comments?

Thanks in advance!

Ed.

[ed_crouch]

Well, I've just been for a drive with the above map for ignition and a well-estimated fuelling map with the other half tuning it on my laptop, and I have to say it runs really well. Im encouraged by the fact that it needs quite a bit more fuel at high loads and high RPMs than the Lucas 4CU-torque-curve-generated map thought I would - I reckon the old 4CU couldnt deliver the goods.

Should get the rest of the map sorted soon, then switch the accel enrichments back on, then set the AFR target map, switch the Lambda correction back on and its there!

Im starting to wonder how much more the ignition needs to be knocked up by...

Oh yeah, starting is massively improved too! Especially hot starting which was utter pish before. AND it'll shunt around the drive on no throttle.

[gsx600]

Sounds good, can't wait to get mine finished and running on the engine , just need a few more sensors again ! Well that and a battery and a few fuel pipes and other ancilliaries

[ed_crouch]

Ah that reminds me - sockets will be dropped off tomorrow!

[gsx600]

Many thanks will take apart tomorrow afternoon

[rev-erend]

Ed,

What spec are you running .. as I'm a bit confused when you say vac advance
- I though you had an ignition map and no dizzy ?

I have checked my map and others and 36 degrees is fairly common at
high rpm. 36 is the highest figure I have used.

My Kawasaki motorbike uses 45 degrees .. but that revs a lot higher.

56 degrees is just rubbish.

[TVRleigh_BBWR]

I've seen some maps with high advance, but this was due to the base setting not being set right, i.e. TDC being at 20, so 56 would really be 36

[ed_crouch]

Hey Rev,

Yeh when I say vac advance I mean extra advance added at lower loads to compensate for the slower burn of lean(er) cruising mixtures, so lets call it load-based advance...!

Yep I run coilpacks. Dizzy was pish so its on oil pump duties only these days and is stripped out inside (lightweight, don'tchyer-know...)

Yeh I thought 56 degrees was a bit flippin hot - but that said the figure of 56 degrees does include load-based advance at top RPM and light throttle...

It seems OKish at the moment, but I've currently got accel enrichments off and EGO correction off while I tune the VE map, plus I reckon I can knock (sic) the advance up a smidge once the fuelling is there. With accel enrich set right and the ignition tuned, it should be quite good.

Actually I could just run 12.5-13AFR everywhere on the map and sod the load based advance!!

Edited by ed_crouch on Monday 31st May 22:31