Ignition Timing
Have been doing some tunning and was wondering what is the optimum timing, seem to be a few depending where one looks. Have a 77 2500 TC Australian car, no egt and electronic ignition. Thanks
-
- Site Admin
- Posts:3593
- Joined:Mon May 08, 2006 9:50 pm
- Location:South Oxfordshire, UK
Re: Ignition Timing
Probably best to start with the book setting and then advance/retard until the engine just doesn't pink under high throttle load at low engine revs. If it doesn't pink, advance it a bit until it does, then retard it until it just stops.
The problem with just using the book setting is that it would have determined over 40 years ago when petrol was a different mix.
Cheers,
Mike.
The problem with just using the book setting is that it would have determined over 40 years ago when petrol was a different mix.
Cheers,
Mike.
(South Oxfordshire)
Register Member No 0355
1971 2.5PI Saloon Sapphire blue
1973 2.5PI Saloon rust some Honeysuckle
1973 Stag French blue
(1949 LandRover was blue should be light green!)
Register Member No 0355
1971 2.5PI Saloon Sapphire blue
1973 2.5PI Saloon rust some Honeysuckle
1973 Stag French blue
(1949 LandRover was blue should be light green!)
Re: Ignition Timing
Thanks, but that is my first problem some books say 8 BTDC, others 10 BTDC. Have tried both and it starts better on 10 but other than that hard to tell.
Re: Ignition Timing
As Mike says, book timing values are now redundant as the fuel now is nothing like the fuel of the 60s/70s.
Get it started and do the pinking tests to get the best settings.
Fortunately this means driving it!
Get it started and do the pinking tests to get the best settings.
Fortunately this means driving it!
Re: Ignition Timing
A 1977 2500 with the 45D distributor would be 10 degrees BTDC. Pre 1973 was 8 degrees.
Charles Harrison
Register member 3095
Folkestone
Cherry Red Mk1 2000 Rally Car
Mallard Blue 2.5PI
Sapphire Blue GT6 Mk3
Vermillion Red Spitfire 1500
Pimento Red TR6
Inky Blue VW Passat B5.5
Arctic Blue Jaguar XJ40
Silver Range Rover Vogue SE
Register member 3095
Folkestone
Cherry Red Mk1 2000 Rally Car
Mallard Blue 2.5PI
Sapphire Blue GT6 Mk3
Vermillion Red Spitfire 1500
Pimento Red TR6
Inky Blue VW Passat B5.5
Arctic Blue Jaguar XJ40
Silver Range Rover Vogue SE
Re: Ignition Timing
Hello Joe,
another point regarding this subject; our cars are now pretty old and over the years the distributor may have been changed to a visually similar but with the wrong specifications for the engine. The workshop manual, if you have one gives the correct numbers, this can be found stamped on the body of the distributor and on the vacuum advance module, either or both could be wrong.
Although the fuel has changed the advance curve is, I believe, more of a factor of the engine specification, so it's worth a check
Alec.
P.S. From the club service notes the correct distributor for a 1977 2500 TC and S is :- 41624, but it doesn't give the vacuum module number.
another point regarding this subject; our cars are now pretty old and over the years the distributor may have been changed to a visually similar but with the wrong specifications for the engine. The workshop manual, if you have one gives the correct numbers, this can be found stamped on the body of the distributor and on the vacuum advance module, either or both could be wrong.
Although the fuel has changed the advance curve is, I believe, more of a factor of the engine specification, so it's worth a check
Alec.
P.S. From the club service notes the correct distributor for a 1977 2500 TC and S is :- 41624, but it doesn't give the vacuum module number.
0465
MK1.5 2.5 P.I.
Jaguar MK 2 (Long term restoration.)
Hymer 564 Motorhome.
MK1.5 2.5 P.I.
Jaguar MK 2 (Long term restoration.)
Hymer 564 Motorhome.
Re: Ignition Timing
Thanks, rechecked timing and went from 8 to 10 btdc starts and runs well with no pinging. So will run it for a while and then see whether it can be improved, will look at Distributor but I put a new one in about 18 mths ago it was a Powerspark 45D6 supposed to be the right one. Also has a Lumination MTK009 ignition. Which when I put them together the Dist cap would not fit so had to grind down the Rotor arm for the cap to sit properly. Don't think it affected anything as car ran well afterwards.
Who is online
Users browsing this forum: No registered users and 16 guests