T16 running problems

[Richard Farrant]

Originally Posted by andrew honychurch

I do wonder why they were specified with 12 volt electrics and a 6 volt coil. Surely not cost cutting?

Andrew,
This was to aid starting, as is done on the Rolls B range engines only they have a 12v coil on a 24v system, running through a ballast resisitor. This is bypassed all the time the starter is engaged, giving double the voltage to the coil to compensate for voltage drop due to starter motor.

[RichardT10829]

I had an issue on a run where mine started to lose power then ultimately called it a day.

The issue was the ignition was drinking the battery dry, the generator just wasn't putting enough juice into the battery.

I had the brushes changed on the generator and the problem never came back.

Should it happen again it's worth checking your battery just after it happens

[andrew honychurch]

Thx Chaps. Will report back asap. E type coil is horizontally mounted on front of cylinder head adjacent to the header tank. Hot hot hot but they work ok. Maybe not as hot. I now have a digital laser thermometer so will be interested to see HOW hot it's getting.

[jeff davis]

Originally Posted by Rhett Fisher

Hi Stewart,
I see that you already have several well informed replies re. your problem but I'll shove in my five pennyworth anyway!
As far as I'm aware, all the 6v flatheads,early or late, use a nominally 4v coil with a wirewound resistor between it and the ignition switch. This resistor is made from Eueka wire which has the property of increasing its resistance as it heats up. This has a very useful effect in basic ignition systems, i.e, the primary current is shared between it and the coil. When the engine is idling the contacts are closed for a relatively long time, so the primary current tends to increase giving the coil a hard time.
However, the resistor counters this so the coil does not cook.
On the other hand, when the engine is at high revs the resistor cools, allowing plenty of current to convert into high speed sparks.
Another handy effect of this system is that if the ignition switch is left on with the engine stalled, the resistor stops the coil going into meltdown if the contacts are closed. I think the resistor should measure about 0.75 Ohms at 20c.
Great care must be taken when setting the contact breakers on 8 lobe cams, as one set 'makes', and the other set 'breaks'. The contacts are NOT 180 deg. apart, which cleverly increases the coil saturation ( Dwell ) time to 36 deg., giving a better spark.A proper setting fixture is best but I have had good results using a vice to hold the distributor, wiring in a coil, plug, battery and resistor, using a drill to turn the dist. shaft at approx. 2000 RPM, using a dwell meter or 'scope to check the results.
A later development of the Ballast Resistor is the cold start bypass system i.e, when the engine is cranked over the heavy starter current drops the battery voltage from, say, 6v to 5v. A separate wire from a terminal on the starter solenoid is fixed to the coil primary terminal, bypassing the resistor, so now there is 5v to a 4v coil and, hey presto, big fat sparks to fire the old girl up! Clever huh! This system overcomes a problem known as coil robbing which some folks may have experienced by the engine firing just as you let go of the starter switch.
Sorry if all this comes over as a lecture but i've always found that things are much easier to fix if you know how they work in the first place!
Good luck,
Rhett Fisher

From an old thread sorry don't know how to bring up except copy paste
Jeff

[eddy8men]

just to add to the confusion a mate has a t16 that was doing the same as yours and he replaced everything without success until someone told him about the localised overheating that the engine suffers from, can't remember what he did but if you know tobin jones you could ask him or I will on your behalf.

rick

[andrew honychurch]

Originally Posted by eddy8men

just to add to the confusion a mate has a t16 that was doing the same as yours and he replaced everything without success until someone told him about the localised overheating that the engine suffers from, can't remember what he did but if you know tobin jones you could ask him or I will on your behalf.

rick

Thank you. I have spoken with Tobin, it was he who fitted a new Electronic distributor. I am just awaiting details on which unit he fitted. .

[andrew honychurch]

Ok. I have not had a chance to
Check on the various items we discussed as yet but I am already some way down the road on this as it's a known fault. Some years ago a friend had a brand new T16 out of a crate. Yes really. Mitch Hickman some if you will know him. His did the same and he got rid of it, I think to the Budge Collection from memory. That was way back in the late 70s

Anyway, I am sure it's the dizzy so I am going to invest in a Mallory three bolt with Petronix Electronic ignition. I know all the risks of an electronic module failing but I am not using this to commute in!

I will report on results. Thanks for the advice

On another note, perhaps worthy of a new thread I have given up on my regulator box. In fact both mine and another take off neither if which work.

On the T16 the regulator looks like a Jeep Delco but has a clamp over it and the contacts are sprung copper plates. I want to replace it with a modern insert and wonder whether anyone can recommend a suitable kit? I know the dynamo is working fine . I have bought these for old motor bikes Perhaps they are available for big boys toys?