Mis-firing Triumph Spitfire 1500 1980

[Pete Lewis]

Pinking happens  with the spark being too advanced the combustion sets up a tin can tinkling rattle from the piston  

generally when in a high gear under load 

makes quite a clatter easily hear with the radio off and the ears open 

low grade fuel will do it quite easily 

Pete

[Iain T]

7 hours ago, Pettifordo said:

What does this sound like ?

Like a very hot exhaust cooling down. A constant tinkling sound when the engine is under load. 

[Stratton Jimmer]

It was the rotor arm that did for me a couple of weeks back when out in the GT6. Fourteen miles with no problem then suddenly no spark at the plugs.

[johny]

Yes many people assume LT problem but really worth checking HT at coil output first to quickly narrow down the search....

[DerekS]

I had a problem some years back with poor starting and an intermittent misfire, (Spitfire1500 ) it was only by sheer luck that I had the bonnet up and noticed that when the engine hiccupped there was a noticeable cracking noise. It turned out to be a complete break in the core of the king lead from coil to distributor, I don't know what caused it but refitting the old one which I'd kept just in case cured the problem.

Derek.

[Peter Truman]

I had a misfire issue with my Dolly Sprint with all the HT leads when I got it 8 years ago I purchased a set of new HT leads with the proper long plug caps ex UK they were graphite/carbon filled & fitted in the small 7mm dizzy cap side entry holes.

I just unscrewed the tapered screws holding the old leads in the cap and replaced the new leads screwing the tapered screws thro the cable and carbon/graphite filling.

all was OK for a couple of drives then the misfire started, upon stripping the dizzy cap down I eventually noticed burning where the tapered screw went thro the cable, this investigation unfortunately took a couple of weeks of pulling my hair out!

After determining the cause I pushed a thin strip of brass up the inner carbon core and bent it back over the outside of the cable, pushed that up the dizzy cap holes and used a flat ended screw to clamp the cable into the cap no penetration of the cable, it required fine alignment of the brass strip and screw. No more misfires and still good many years after.

An old hand was looking at the arrangement and advised me to hold the graphite cables as if they flapped around the core could break causing a misfire so obviously I made HT cable clips to stop any excessive movement.

[Pettifordo]

I fitted the Accuspark and it worked…..then didn’t work….then worked

When it didn’t work the engine was struggling to even turn over and the rev counter was going bonkers…..

Anyone got any ideas what could be going wrong ?

Also what does the cloth covered wire in the dizzy do ? It was under the condenser - so I still need it ?

[Josef]

I’m not completely certain, but this feels like the equivalent of the points shorting (the coil -ve being earthed at the wrong time)

[Pettifordo]

50 minutes ago, Josef said:

feels like the equivalent of the points shorting

Thanks - I will check all the connections again - I think I will replace the earth wire to the coil as it has those dodgy blue connectors 😱

[johny]

1 hour ago, Pettifordo said:

Also what does the cloth covered wire in the dizzy do ? It was under the condenser - so I still need it ?

That sounds like the critical wire to earth the dizzy backplate while allowing it to move. This is still needed with the Accuspark which must have its base earthed to function. Be careful with the unit as, unlike points, if installed incorrectly you run the risk of knackering it....  

[Pete Lewis]

that braided wire is essential it makes the moving base plate earth to the case 

as you cant rely on the two part base plate making its own contact 

having recently been plagued with accuspark units failing i have resevations about them  

many are used quite successfully , but there are others with odd problems 

Pete

[Pettifordo]

I think I have found the problem with the ignition - a dodgy negative wire from the coil to the dizzy.

The PO had fitted one that had those blue crimp spade connectors.

Having determined that the strange intermittent issue I was having with the Accuspark was probably connected to a dodgy Earth connection - thanks @Josef

I just soldered on 2 new connectors and took her for a drive - runs very nicely.

That probably means I didn’t need the following :-

1) Accuspark

2) Coil

3) Buy Colortune to check mixture

4) Buy timing light to check timing

5) I also suspect I didn’t need a new dizzy cap or rotor arm

🤞🤞

 

[AlanT]

At least you've found it. I had a very similar issue. The same cable had a spade connector, mid point. It would be OK at idle, start missing after a few miles. Replaced with a soldered joint and bingo!

[Pettifordo]

2 hours ago, AlanT said:

spade connector, mid point

Mine still has a spade connector mid point…..would a bullet connector be better ? Or should I just solder the spade connector together ?

[Pettifordo]

22 hours ago, Pettifordo said:

That probably means I didn’t need the following :-

I forgot the fuel pump that I also replaced and then found out that the replacement leaked fuel all over the starter motor 😩😩😩

I didn’t try to find out where the problem was - I just added the old one back on.

[dougbgt6]

Pinking is a sort of ting! ting! ting! noise, a tack nail rattling in a tin.

Doug

[AlanT]

1 hour ago, Pettifordo said:

Mine still has a spade connector mid point…..would a bullet connector be better ? Or should I just solder the spade connector together ?

I cut off the connector & soldered the two wires together; tightly covered in electrical tape. The mid point connector has no value and is an obvious candidate for getting lose over time / damp. 

[Wagger]

On 13/04/2023 at 09:17, Pete Lewis said:

not much you can do to test a cap  maybe a look in the dark for stray sparking 

any rotor witha rivet in the sweep contact are prone to fail as the spark will jump  from the rivet to the shaft 

condensers are often fake  and have very little inside  see the dizzy docs review Delco condenser: RD7774, CD369, 829111,829107,1861709,1866049,18655972, 1869704,1882239, Lucas Condenser 484249, 400308, 407044, 54411935 / DCB105, 54413006, 23D4 22D 23D DM2 25D DM6 DM4 lucas distributor, Lucas condenser number 423871, GDC101. Condensor 405833 for Ford 8 and Ford 10, Lucas condensers from Distributor Doctor

pete

I have a quite expensive multi-meter that will measure capacitors in Picofarads, nanofarads or microfarads. Cost £150 in 1997 made by Tektronix. Even so, it  can be fooled by breakdown at high voltages. Arcing points is a sign of a capacitor with low or no capacitance.

An Oscilloscope and signal generator are the best tools if you can find and know how to use them.

[Pettifordo]

Just got myself a lesson in carb tuning from Mark Smith who runs the new South Warwickshire TSSC Area.

He took me through the whole process top to bottom :-

Checked for air leaks

Check for unrestricted rise and fall of carb jets

Started engine running (was already at operating temp)

Looks at carb balance by eye and adjusted tick over screws to get balanced

Used flow meter to tweak further at idle

Increased revs to 2500 and check balance again.

Tweaked the linkage between carbs to make sure balanced.

Lifted carb jet by a few millimetres to listen to engine / decrease revs = too lean / no change = just right / increase revs = too rich (thanks to @Pete Lewis for correction)

Anti clockwise on the jet adjuster to make richer, clockwise to lean - do one flat at a time

Engaged choke so revs increased and balanced carbs again

Listened to the exhaust for pops (too lean) or smelling too much petrol (too rich)

Took her for a test drive 👍

 

 

 

Edited April 23, 2023 by Pettifordo
Correction from @pete Lewis

[Pete Lewis]

19 minutes ago, Pettifordo said:

decrease revs = too lean / no change = too rich

thats not quite right   raising the air piston a few mm is fine but 

you are looking/listening for a hint of change so if the revs drop by about 50 rpm for a few seconds its lean

if it raises idle by 50rpm its rich 

if the lift has no real effect its spot on 

its a very light  touchy feely pin lift , yank it up and its will just stall  

small detail  but youre on the right track 

Pete

[Pettifordo]

2 hours ago, Pete Lewis said:

if it raises idle by 50rpm its rich 

Thanks @Pete Lewis that make sense - I guess if it is rich and you let in more air you get a bigger bang as the “excess” fuel is burned 👍👍

Edited April 22, 2023 by Pettifordo

[Pettifordo]

Just went out to put the car away after my great drive home from Mark’s and the car wouldn’t start.

Seems like the Accuspark Electronic Ignition had failed after 15 miles 😩😩

popped the old points and condenser back in and it worked fine - just need to adjust the timing again 👍

[AidanT]

18 minutes ago, Pettifordo said:

ms like the Accuspark Electronic Ignition had failed after 15 miles 😩😩

Your not the only one who's had issues with accuspark. Got that T shirt some time ago now!!

Aidan 

[johny]

As a double check of the Accuspark unit you can test it manually by connecting the red wire to a 12v battery +ve, the unit backplate to the -ve and then put a meter. set to resistance, on the black wire and -ve terminal. Now when you pass the magnetic trigger head across the face of the unit you should see a momentary change in resistance as it switches on...

[Pete Lewis]

Accuspark units are certainly an economical fix  the base units seem well made but there are too many reliability issues  

whilst you get what you pay for  the mechanicals seem better than the electronic modules 

I have only played with one used to replace a failed 123 and it took accu to provide a replacement module  good /quick service but we need these things to Work 

Pete