Help Please.

[Rod Mathews]

I hope someone out there may be able to offer some suggestion.
I have recently rebuilt a grey motor (approx 3 months ago). Recently I have been experiencing problems. It tends to run quite rough and lacks power, so much so that it will stall if you tend to take off in first.
Early on I had trouble with a sticking valve (the head was reconditioned) but this is not the problem. The points were badly pitted and have been replaced. I suspected it may have been an initial fuel problem as I gave it drink down the carby's (yes twins) it seemed to help. I pulled the fuel pump apart and found the one of the valves was completely buggered. Replaced and seemed to work ok for a day and problem reappeared. I pulled distributor apart and vacuum and counter weights seemed ok (timing was out somewhat but this didnt help greatly). I cleaned the contacts within the dissy cap which had solid white deposits on them as well as the rotor.I swapped the coil over but this hasn't helped. I expected crook fuel but I filled up  again(it took 3/4 of a take). I was hoping this may dilute the fuel enough.

The problem that I am experiencing is that the problem is spasmotic. I could be driving along while lacking power and all of a sudden everything is ok. This is why I have not pulled the carbys down and cleaned.
It doesnt seem to be a head gasket as its not using water. One thing I've yet to look at properly is vacuum leaks

Can someone please help.
Many thanks
Rod

[craiga]

Hi Rod,

With intermittant problems I reckon its worth looking at everything again but with a systematic approach.

• Check point gap and condition. If in doubt replace 'em
  
• Check disty advance plate/weights are free
  
• Set the timing manually (the original manual describes the procedure)
  
• Check the plug gap and condition
  
• Check and clean the HT cables
  
• Check the rotor closely for cracks and condition
  
• Check the cap for cracks and carbon tracking
  
• Check the center carbon contact in the dizzy cap - the spring sometimes sticks and causes problems like your experiencing
  
• Check the fuel pump output - remove the fuel to carby pipe at the carby end and direct the output to a container. Crank the engine over and the container should fill very quickly, this is especially important with your twin carbs - your basically asking the standard pump to do twice the work!!
  
• Start him up and set the linkage adjustment using a carby balancing tool - you can buy these for about $40.00 from Rare Spares. Cheap  for the frustration it will save trying to set up the balance on your carbies.
  
• Adjust the mixtures by turning the mixtures screws OUT until the engine begins to falter. Turn them back in half a turn and you will be close enough. With LRP I have found it is better to run slightly rich than slightly lean.
  
• Use a vacuum gauge to confirm steady 14" HG or above at idle
  
  

This should correct most problems - but if not look further at primary connections or the condensor. I reckon if your not prepared to pay someone else its a good investment to buy yourself at least a carby balancer, vacuum guage and timing light.

Good luck,

Craig.

[Rod]

I have been working on the old girl again tonight. After an initial problem she has been running ok. My question is, could a faulty battery / generator case this problem? The reson I ask is two fold. Firstly, the battery has unexpectedly gone flat a few times in the last month (i thought there may have been a current drain from the heater as I left the fan on once turning the ignition off). The generator idiot light does not glow so I assume the generator should be ok.
Secondly about 10 to 15 years ago I had an old XB Falcon in which the alternator failed on a trip. The car ran perfectly drawing on the power of the battery for spark generation. However, as it got dark I had to use the lights which began to flatten the battery at a faster rate. As the battery got flatter the car began to lose power similar to what I am experiencing now.
So could the battery be the source of my problems? I hope someone maybe able to help.

Thanks again
Rod

[Rod]

Many thanks Craig for your response. You must have posted it as I was typing my most recent response. Craig I actual, went about it systematically as you have discussed, but timed the old girl using a timing light and not manually. The only thing I didn't look at was the centre carbon contact. Everything else I covered. I will look at this immediately, many thanks.
One other observation I failed to mention was I happened to touch the coil accidently (the replacement one) once the motor had been running for some time. It tended to be quite hot. I am unsure if this is normal.
Thanks Craig

Rod

[craiga]

Rod,

It is possible that a faulty battery would cause your problem. The coil requires about 8 amps to operate effectively so a flat (or lower output) battery would definately cause your problem (Low primary voltage= low secondary voltage). If the battery is going flat then either it is bad (plates are stuffed or low water) or the generator or regulator is not operating effectively. If you have a voltmeter you should see about 13-14 VDC at about 2000 RPM. If not at this level this could be your drama.

You said you replaced the coil? A standard grey motor coil doesn't require a resistor in series to limit the current to the primary winding and therefore the points: but later model coils MUST have a resistor in series or you will overheat the coil and burn out the points. Most resistor coils have an "R" stamped after the part number - usually found on the base of the coil body.

That said a normal engine runs at about 75-85 Deg C which feels hot with a finger attached to a body that runs at 37-38 Deg C  

Keep looking, your getting closer............

Cheers,

Craig