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Author Topic: ignition timing  (Read 4060 times)
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dhla40
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« on: 18 August, 2009, 06:20:45 PM »

As the ignition timing for the fulvia was probably optimised for leaded fuel in the early seventies has anyone experimented with different settings for modern fuels and found any benefit.  On my alfa's a slight increase in static and a couple of degrees less advance is considered a good idea.  The max advance of the S105C dizzy on my car at 23 degrees does seem a bit low.

Sean
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1976 1.3s coupe
1973 1.3s coupe
1982 montecarlo project
1976 alfa GT
1981 alfa spider
ColinMarr
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« Reply #1 on: 22 August, 2009, 05:09:50 PM »

The 1600 engine in my Fulvia had been rebuilt in the 1980s and the head had been planed, presumably just to flatten it, but it must have a slightly higher CR than usual. When I put it back on the road in the mid 90s it suffered badly from pinking, and I experimented with modifying a distributor. To restrict the amount of automatic advance I limited the movement of the weights by adding weld to the slots in the plate and filing it to shape so that the movement was half the original, which I think meant 6.5 degrees ‘static advance’ rather than 13. This was a mod that Barry Waterhouse was aware of and I asked his opinion before doing it.

I think it improved things a bit and enabled me to set the engine up for a reasonable tick-over and not too horrible pinking when under load, although it was still necessary to be gentle in opening up the throttles. Some time later I rebuilt the 42mm carbs, which seemed to improve things even more. I then experimented with octane boosters as they became more readily available, which seemed to solve all my problems.

I am now back with the unmodified distributor. I use Tesco 99 petrol when available (as far as I know this is the only popular option which is 99 octane), or standard 95 unleaded with Castrol Valvemaster Plus to bring this up to 99 octane. Both of which seem to work well for normal road use. If I ever venture back into track-day use I will again use 99 plus octane booster, which seemed to work very well when I last did Castle Combe in 2007.

Colin
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angelorange
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« Reply #2 on: 08 September, 2009, 11:00:33 AM »

Try running on Shell Optimax 99 with Castrol Lead replacement/booster - My 1600 works fine with 27 deg max advance on std distributor/points plus MSD spark set up.
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dhla40
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« Reply #3 on: 08 September, 2009, 05:43:44 PM »

Have had a play around with the timing and have modified the dizzy to give 25 max with static of 12, idle is much smoother and cant hear any pinking yet.  Runs ok around town but need to take it on a long run for final verdict.

Sean
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1976 1.3s coupe
1973 1.3s coupe
1982 montecarlo project
1976 alfa GT
1981 alfa spider
lancialulu
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« Reply #4 on: 08 September, 2009, 06:30:35 PM »

My experience is somewhat different with only playing around with the static timing figure on (normal) 10 deg on my HF.

I did have terrible pinking like Colin but could reduce it by increasing static to c 15deg.

I then needed to remove the head (cam cap bolt threads had gone soft) and on retiming the cams very carefully with a protractor I found no pinking what so ever even at the 10 deg. I now run in preference Shell Optimax 98 (?) and no octane enhancer. I use Castrol valve master plus on a 1300 to protect the valve seats.

Tim
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Its not the winning but taking part! or is it taking apart?
1955 Aurelia B12
1967 Flavia Vignale iniezione
1967 Fulvia 1.3HFR
1972 Fulvia 1600HF
1972 Fulvia 1600HF
1972 1600 Fulvia Sport
1979 2500 Gamma Coupe
1988 Delta 1.6GTi
1998 Zeta
angelorange
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« Reply #5 on: 08 September, 2009, 09:25:30 PM »

Hmmm,  yes that fuel is v god for Fulvias.

Lancia manuals suggest 8 deg static for S1 and S2 1600's except var 1016 which had 10 deg static.



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ColinMarr
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« Reply #6 on: 09 September, 2009, 05:48:30 PM »

Sean,

The 25 degree maximum figure you quote is not familiar to me so I looked back into my documents and notes on the mod I made in 1998.

The maximum advance will be the sum of two figures: one for the amount of ‘fixed advance’, which will usually be determined by the marks set on the flywheel (TDC and A/A) and the other by the amount of the ‘automatic advance’ determined by the weights and springs in the distributor.

I don’t have a figure for the ‘fixed advance’, but from what you have posted it looks like this might be 15 degrees (?).

My distributor is type S139A, which was fitted to all 1600 Fulvias (including var 1016) and is designed to give ‘automatic advance’ of up to 10 degrees. The curve for this should be similar to your S105C, which shows increasing advance from zero at 400 rpm up to 10 degrees at 3000 rpm.

The modification that I made was to limit the movement of the weights so as to give a maximum automatic advance of 5 degrees. The original length of the slots in the base-plate was 7.4 mm and the pins on the weights were 5.0 mm diameter. Weld-metal was put into the limit-end of the slot, which was cut back to give a reduced slot length of 6.2 mm, i.e. halving the free movement from 2.4 mm to 1.2 mm.

As I posted earlier, this mod helped but the real solution was to use octane boosting additives when they became readily available.

Colin
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lancialulu
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« Reply #7 on: 09 September, 2009, 05:56:53 PM »

Just to confirm my use of the word "static" is the same as fixed. My HF and 1600Z have standard distributors, modified cams (one very like a var 1016 if only anyone knew what they were like!!, the other a holbay rally cam with similar lift and overlaps to the "var" one), and I use 10deg fixed/static and absolutely no pinking under any load and any (low) revs.

Tim
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Its not the winning but taking part! or is it taking apart?
1955 Aurelia B12
1967 Flavia Vignale iniezione
1967 Fulvia 1.3HFR
1972 Fulvia 1600HF
1972 Fulvia 1600HF
1972 1600 Fulvia Sport
1979 2500 Gamma Coupe
1988 Delta 1.6GTi
1998 Zeta
dhla40
Senior Member
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Posts: 122


« Reply #8 on: 09 September, 2009, 06:16:04 PM »

Hi Colin

I have limited the auto advance on mine in a similar way but instead of welding I fabricated a small clip of metal which I fitted over the hole in the baseplate.  This has reduced the advance to about 13 degrees flywheel so with static set at 12 max advance ends up at 25,  I still have to give the car a good run to see if I prefer this setting and may end up returning to standard.

Sean 
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1976 1.3s coupe
1973 1.3s coupe
1982 montecarlo project
1976 alfa GT
1981 alfa spider
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