No spark at plugs

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paulsv8manta
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Re: No spark at plugs

Post by paulsv8manta » Thu May 24, 2018 2:13 pm

Just had a thought, should the coil be earthed?



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stevieturbo
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Re: No spark at plugs

Post by stevieturbo » Sat May 26, 2018 11:10 pm

paulsv8manta wrote:
Thu May 24, 2018 2:13 pm
Just had a thought, should the coil be earthed?
What type of coil ?

Regular 2 terminal coils...1 wire is power, the other is the ground via the points, electronics, dizzy...whatever trigger you're using.

So in that sense, no, no terminal should see a solid ground.
9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

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Re: No spark at plugs

Post by paulsv8manta » Sun May 27, 2018 5:00 pm

Ooops I didn’t explain myself properly, on my Opel manta the coil housing has a metal bracket as part of the unit which in turn is bolted to the chassis so it’s earthed to the car. So I was wondering if the v8 should be the same?

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Re: No spark at plugs

Post by stevieturbo » Sun May 27, 2018 10:17 pm

Lots of cars they probably are earthed....not sure whether it is deliberately though, or just because metal makes for easy brackets.

But in terms of functionality of a typical oil filled coil....pretty sure there is no reason to earth the body.
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http://www.youtube.com/watch?v=XgWRCDtiTQ0

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Re: No spark at plugs

Post by paulsv8manta » Tue May 29, 2018 8:39 pm

Well guys I think I have found the problem. As I've stated before the coil I am using is the Bosch blue: 0221119027 apparently they make different versions.
Ballast ignition systems were introduced in around 1970. To find out for sure, use a multimeter to check the voltage on the positive wire of the coil with the ignition on. Around 9v means you have a ballast, around 12v means you don’t. I've got 12v.

Which coil should I use with a non-ballast ignition system?
Use any standard non-ballast coil, or a performance non-ballast coil from Bosch (blue coil 0221119027). Do not use a ballast coil. Although you may gain a performance advantage using such coils, failure will be imminent!
A non-ballasted coil for systems without voltage increase for starting. This coil provides more starting power than standard energy ignition coils. This ensures smooth engine running and good starting performance. For engines up to 6 cylinders

Measuring Coil Primary Resistance: 4-Cylinder: Coil must have a minimum of 3 Ohms primary resistance. 8-Cylinder: Coil must have a minimum of 1.5 Ohms primary resistance. My Bosch blue reads 3.3 Ohms.
Measuring Coil Secondary Resistance: For best performance, coil should have 7K Ohms or more secondary resistance. My Bosch blue reads 7.29K Ohms.
So now I'm thinking I need the - Ignition Coil - Electronic Distributor - GCL143 - Lucas

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Re: No spark at plugs

Post by Eliot » Tue May 29, 2018 9:24 pm

How decent is the spark from the king-lead? You say you have 12v and a non ballast (12v) coil - which means your coil is correct? Even if you have a ballast coil, you can try hard-jumping 12v direct to the coil+ to eliminate all wiring and the 12v boost wire from the starter (or a relay) - dont leave permanent 12v to a ballast coil, it will overheat.

Have you checked that the dizzy is alinged to the tower - easy way to check, given you appear to have several spare caps is it cut a hole in the side of one. You want the engine at say 10' btdc on cyl#1 and check that the rotor is pointing close to that tower.

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(photo is of a Chevy HEI dizzy which is MUCH bigger, but you get the idea.
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Re: No spark at plugs

Post by Ian Anderson » Wed May 30, 2018 5:16 am

Have you got a decent earth strap to the engine?

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Re: No spark at plugs

Post by paulsv8manta » Wed May 30, 2018 6:09 am

Hi Elliot I’ll cut one open today.
Ian I’ve not only got the Earth stap on the rear of cylinder head I’ve also got two more one bolted to each engine mount.
I’ve got 12v on terminal B of the ignition module from the + terminal of the coil.
I’ve got 12v on terminal C of the ignition module from the - terminal of the coil.
The module is securely earthed.
With the ignition off I’ve checked the resistance across module terminals G & W whilst moving the dissy the resistance alters as small voltage is being created by the pick up coil as the rotor moves.
I’ve taken the king lead from the coil with a spark plug inserted I’ve got a very weak spark.
I’ve also stripped down the dissy cleaned and lubed the internals checked the air gap of the pick up and reset it to .010 clearance.

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Re: No spark at plugs

Post by DaveEFI » Wed May 30, 2018 8:50 am

The only way to measure the voltage across the coil with the the system firing and taking load is with a 'scope. A voltmeter won't react quick enough as it's a series of fast on/off cycles. And measuring voltages with no load on the curcuit is pretty pointless.
You need to have the correct positive voltage to the coil under load. This will either be battery volts or something closer to 9v, if a balllast resistor start system. The electronics should provide as near as dammit 0v when it makes the circuit to the coil primary. But as I said not really possible to measure with a DVM.

There are different systems used on the SD1, and I've only ever had the last type, the DLM with amp on the side of the dizzy. According to the manual, the earlier DM dizzy had a resistance wire in the loom, so had some form of cold start system.

Ramon Alban IIRC did a pretty comprehensive description and fault finding guide on the DM system.

http://www.vintagemodelairplane.com/pag ... ion01.html
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Re: No spark at plugs

Post by paulsv8manta » Wed May 30, 2018 7:09 pm

Thanks Dave I checked out Ramon Alban site via the link, there was section on Testing Amplifier & pickup Coil together connect 12v 21w bulb between W/B & W wires, 12v coil positive, turn ignition on and gently rotate distributor rotor arm back & forth, the reluctor wheel triggers the pickup coil and amplifier will light the bulb. (Mine flashed once!) If flashing is absent, weak or inconsistent either the amplifier or pickup assembly is faulty, so: Detach pickup coil connections at amplifier using an ohmmeter measure the resistance of the distributor pick up coil. Expect a steady value between 500 to 1500 ohms.

Mine reads 3.335

A result outside the specified rage, short or open circuit indicate a duff pickup coil.
Looks like I need a new distributor. The problem now is finding the right distributor.

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Re: No spark at plugs

Post by DaveEFI » Thu May 31, 2018 8:34 am

If your dizzy is otherwise good, I'd look for a cheap used one and swap the VR sensor. That bit is normally pretty reliable. Best place to ask would likely be the SD1 forum and of course Ebay.

http://www.roversd1club.net/forum/default.asp

or a a Range Rover/Land Rover one.
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Re: No spark at plugs

Post by sidecar » Thu May 31, 2018 3:31 pm

I probably have a sensor kicking about that you can have for the price of the postage. I've not been reading this thread in any great depth so forgive me but have you actually measured the resistance of the sensor and found it to be out of spec?

Edit just check my 'junk' box, I have three pickups, one has short leads with no connectors on the ends at all, the second has short leads with a connector that is also a grommet that would sit in the side of the dizzy body, it has female connectors. The third has longer leads, it has a grommet half way along the leads and then at the end of the leads is a black connector with male spades. All three pickups read 3.3 -3.4 K ohms

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Re: No spark at plugs

Post by paulsv8manta » Mon Jun 04, 2018 5:23 pm

Hi Sidecar, thanks for your input I've rechecked my pickup and its 3.3K Ohms same as yours so it can't be the pickup!
I've now narrowed it down to the Ignition Amplifier
I've delved further into Ramon Alban site and found this little snippet,by connecting a 1.5V pen-cell in series and two flying leads.
Connect king lead to a spark plug.
Disconnect the two pickup coil signal wires from the amplifier.
Connect one flying lead to one amplifier input terminal.
Switch ignition on.
Touch the second flying lead briefly to the other amplifier input terminal.
The amplifier should activate the coil and produce a sparkat the spark plug.
The pulsing voltage from the pen-cell triggers the amplifier....Not happening with mine no voltage whatsoever is coming through the amplifier.
So this must be the culprit! Ordering a replacement tonight fingers crossed.

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Re: No spark at plugs

Post by DaveEFI » Tue Jun 05, 2018 8:28 am

The amp is the most likely part to fail by a considerable margin, after cap rotor arm and leads.
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Re: No spark at plugs

Post by paulsv8manta » Mon Jun 11, 2018 12:16 am

I can’t thank you guys enough. Finally got it sorted it was the amp! Cheers. 😃

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