Print Topic - Archive

Triumph Torque  /  Spitfire/GT6  /  GT6 timing for 95 Octane petrol?
Posted by: markcro, June 11, 2016, 8:01pm
Hi, what do people usually have their timing set to for 95 Octane. (and before people tell me that they only use 98 Octane Super, well I am very jealous as here we only have crappy 95 Octane dish water :-( )
The factory setting is 7 degrees but that is obviously for 100 Octane leaded back in the day. So I have mine currently set to 13 degrees but she still overruns a fair bit on shut off.
Posted by: glang, June 11, 2016, 9:03pm; Reply: 1
Hello Mark, Im a bit confused as it sounds as if you have more advance on your timing than the factory setting! I use an octane additive on my vitesse which greatly improves the running and run on but have also adjusted the timing so that, as recommended, the pinking just stops at 2000rpm as I accelerate on the flat in 4th....
Posted by: cook1e, June 11, 2016, 10:16pm; Reply: 2
It's not just the octane rating, issue with modern fuels is also the high ethanol content. Even running on V-Power Nitro plus which is 99RON, I've found that I have to retard the ignition to 6 degrees otherwise it pinks on my GT6 MK3. A few years back it would run OK at 10 degrees on 97 RON petrol, but that was before they were allowed to put ethanol in the fuel. To run on 95 RON I suspect I'd have to retard even further, say to 4 or 5 degrees. On the RBRR when decent petrol isn't available up in the wilds of Scotlandshire the last time I used the GT6 I just put up with a bit of pinking!

My Dolomite 1500 is much less of an issue and runs OK on standard unleaded without pinking, but hen they were designed to run on 4 star unlike the GT6 which was designed to run on 5 star (100 RON) when new.
Posted by: markcro, June 12, 2016, 12:03am; Reply: 3
Quoted from glang
Hello Mark, Im a bit confused as it sounds as if you have more advance on your timing than the factory setting! I use an octane additive on my vitesse which greatly improves the running and run on but have also adjusted the timing so that, as recommended, the pinking just stops at 2000rpm as I accelerate on the flat in 4th....


Hi, okay maybe I'm doing this arse ways. So which way is retarding the ignition timing? Is reducing the standard time of 13 degrees to 7 degree advance not retarding it? Or is it is actually increasing it? Feel free to explain it in baby steps. :-)  Cheers! :-)
Posted by: Dannyb, June 12, 2016, 7:24am; Reply: 4
Dizzy neeeds to turn anti clock wise to retard and clock wise to advance
Posted by: BrendanD, June 12, 2016, 8:12am; Reply: 5
I had mine set up on a RR with a 123 Tune ignition, but I run it on V power Nitro. No pinking. Its 10 degrees BTDC with a custom curve.
Posted by: markcro, June 12, 2016, 8:25am; Reply: 6
Cheers guys. One last stupid question so that is is clear in my head: So me running 7 degrees BTDC is less timing/retarded compared to the 10 degrees above?
Posted by: cliftyhanger, June 12, 2016, 8:47am; Reply: 7
7 degrees is less advanced (or more retarded) than 10.

Best way to get it spot on is to advance the timing until the car pinks when driving under load, then back off until you no longer get pinking. I did that, and the rolling road could not improve it. Fully mapped ignition is better, but if using a dizzy then "by ear" seems the best solution as it allows for wear/fuel etc
Posted by: glang, June 12, 2016, 11:26am; Reply: 8
Mark maybe the confusion comes from top dead centre which is where the piston reaches it highest point and is marked on your bottom pulley. The spark should come before this point ie the piston is on its way up and the more degrees of crank rotation before the more advanced it is. However a spark after top dead centre (which shouldnt be the case as the piston is on its way down) will be more advanced the less degrees after top dead centre it comes.
Hope this helps....
Posted by: GT6 M, June 12, 2016, 6:49pm; Reply: 9
a wee bit of info that may go owa most folks heed,
butt, its applicble to this thread.

ages ago, decided to mek a map for the car using 95 fuel
thowt id run engine in OD top, and nok timing back till it stopped.

at aroond 25-35% load, and 2000 - 3000 rpms, i had aboot 3 degs of advance,
98 fuel was 18 degs
at just off idle,1200  1600 and 10% load, I had 0 -2 degs advance, 98 was 7 =11 degs

at top end, original map was 27  dges
I was doon to 22 degs

ye just cant say that nok,n this of here and that there wil be OK, it wont.

Butt, car still went well wid thee,s figs

Did this just in case I could,nt get any 98 any where.
And,I must,v deleted this map, as cant see it noo, on me pics albums
will try me memory stik, it,ll give a good idea what im on aboot.

M
Posted by: markcro, June 13, 2016, 9:08am; Reply: 10
Thanks guys. The next problem that I have is that I don't know what pinking sounds like. Don't know if I'm tone deaf or what?! :P
Posted by: BiTurbo228, June 13, 2016, 9:21am; Reply: 11
Quoted from markcro
Thanks guys. The next problem that I have is that I don't know what pinking sounds like. Don't know if I'm tone deaf or what?! :P


I'd be interested in this too. Not sure I've ever heard it, or at least I've never been there when someone's said 'that engine's pinking'...
Posted by: cliftyhanger, June 13, 2016, 10:08am; Reply: 12
Low revs, up an incline , foot down on the accelerator. Sound is like pins in a tin can being shaken. Sort of.
Posted by: markcro, June 13, 2016, 12:40pm; Reply: 13
Quoted from BiTurbo228


I'd be interested in this too. Not sure I've ever heard it, or at least I've never been there when someone's said 'that engine's pinking'...


You see this is my problem as I have been. My friend in his old yoke was saying "You hear that pinking?!" I was like "Erm no..."   "There, there!"   "Erm, no I can't hear anything...."

Posted by: Toledo Man, June 13, 2016, 7:03pm; Reply: 14
I used to run the Dolomite on 95 octane. Since switching to super unleaded I wouldn't go back. It costs more but it runs so much better on the higher octane stuff and you can use the book figures. I'm running Shell V Power in the Dolomite. I'll only put the 95 octane stuff in the moderns.
Posted by: GT6 M, June 13, 2016, 7:36pm; Reply: 15
its strange to me, folk say, Super unleaded,  or the like

most of the fuel, BP,Esso, ect, its just 97
shell, Tesco  98/99, but full of ethanol, which Ive found actually weakens me mixture, so really need to add moer fuel!!

Butt, 97 wasless than good ole 4 star, 98 same,
so yer only bung,n in, what yer car was designed to run on.


this 95 stuff its aboot what the olde  3 star was.
only cars I recall running onit were all the new Jap imports int early /mid 70,s

1 star was the lowest grade  
2 star was 92 octane,
3 star  95,  
and 5 star 101 octane, good ole stuff, but dear then

M
Posted by: Brit car fan, April 20, 2017, 4:08pm; Reply: 16
Hi Guys, sorry to put in a question of my own her - what's the best juice to put in my spitfire 1500 (UK 9:1 compression)? Currently running on the cheap stuff, Static timing 8deg BTDC, dynamic figures just within or on top end of BL manual limits (bearing in mind it was written for that toxic leaded pooh). I've recently rebuilt the engine and there's this nasty tinkly noise (like someone shaking a load of pins in a biscuit tin) coming from it - not sure if pinging (pinking?) or small ends. I've checked the backlash on the timing chain and seems ok.
Thanks, Dave.
Posted by: glang, April 20, 2017, 4:33pm; Reply: 17
Hi Dave, is this noise all the time or only when you put your foot down especially at lower revs in a higher gear going up a hill? If its the latter it'll be pinking so try running it on super unleaded. If it still does it try gradually retarding the timing (less degrees BTDC) until the noise just stops at 2000rpm in top gear under full acceleration on a flat road.
Posted by: cliftyhanger, April 20, 2017, 5:46pm; Reply: 18
Leaded petrol wasn't that bad!

Anyway, as above it sounds like pinking. Just keep retarding the ignition until you no longer get pinking.
Higher octane fuel will also help.All as glang has said.
Posted by: Brit car fan, April 21, 2017, 11:41am; Reply: 19
Thanks Glang and Cliftyhanger, Yesterday I put some of the expensive juice in (Shell V-power nitro) - 99 RON, currently a 50% mix in the tank. Went for a good old drive yesterday but still noisy when I got home - seems to be on acceleration, deceleration and light running, so not too optimistic :(

Have been plotting the dynamic results on a graph, along with the BL advance curve envelope and it's now advancing well above envelope limits. I think the engine's been knocking all along and now might be too late.

I'm going to retard the ignition to 4deg BTDC to see if it helps, also in the distributor the secondary spring, which is supposed to come into play at 1400 rpm is not cutting in until 2000 rpm, I know it's worn / stretched as it measures 0.722" inside the hooks, which I think should be 0.700"
I bought a range of springs from Moss but none seem to give the right curve.
Looks like I'm going to be into some experimentation with dizzy springs - even winding my own as I can't find the exact Leyland one (wire dia 0.051", 4turns, o/d about 7mm).
Interesting read here:

http://mgaguru.com/mgtech/ignition/pdf/tuning_lucas_dist.pdf

Thanks guys, Dave
Posted by: glang, April 21, 2017, 1:39pm; Reply: 20
Dave, I just remembered that mines a lot worse if I dont keep the oil level topped up in the stromberg dashpots. However that again only really gives you pinking under accelelration so if yours is all the time it might be something else....
The good news is, as I understand it, that its pretty difficult to do really serious damage just with pinking - youre talking race and drag engines rather than our lowly examples ;D
Posted by: Brit car fan, April 21, 2017, 7:11pm; Reply: 21
Thanks Glang, I've got twin SU's on mine but I'll check the dash pots and top them up. Got the distributor stripped down at present, to find where all that stray advance is coming from. There also seems to be some residual backlash in the distributor drive which doesn't help.

Dave
Print page generated: August 18, 2017, 12:41pm