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Any battery 4-5 years old or older is suspect. You should be getting over 12 volts from your alternator at idle speed. An old battery will draw this voltage down in an effort to take a charge. If your battery is old, I would replace it now, and then go on with other tests if you are still having problems
 
DayleW said:
I'm pretty sure i've got this right. I used the calculation in the multimeter manual. It's a 4 cylinder so the cam has 4 lobes spaced 90 degrees apart. The formula is dwell-in-percent/100 * period of cam. The reading on the multimeter set to position 2 for dwell angle readings is defenetly mostly between 8 and 10%, with the odd spike up to 50%. I've checked the points gap with a feeler gauge and that seems correct (0.015 inch), so i've ordered a new set of points. The old ones do seem a bit pitted.
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Apologies If I am insulting your intelligence here (or showing my lack-of here! :p)

You have a Gunson's TestTune (sp?) unit? IIRC, that has a switch to change between 4, 6 and 8 cylinder engines. You haven't got the switch in the wrong position, do you?
 
The new points and condenser have just arrived. I'll put them in after lunch and see if things improve.
 
I cant even get her started with the new points. I put the old ones back in and checked the dwell angle after tweaking up the idle speed. I get a dwell of 65% when the engine idles at 900rpm. Any lower than that, the ignition light comes on and the dwell angle drops down. I find it all very confusing :? .
 
DayleW said:
I get a dwell of 65% when the engine idles at 900rpm. Any lower than that, the ignition light comes on and the dwell angle drops down. I find it all very confusing :? .
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The dwell angle should remain the same regardless of engine speed. The ignition light shouldn't come on at anything near those sorts of RPM.
 
Rather than rely on a dwell meter that might be giving misleading readings, would it be an idea to maybe just set the points to the gap when fully open to that specified in the manual (0.015 inches) with a feeler gauge? This might not give you perfect dwell angle. However, assuming everything else is in good health, it should be close enough.

I've used a few DIY dwell meters over the years and they ranged from being quite easy to use and seemingly accurate to giving quite bizzare obviously nonsense readings.
 
JVY said:
Rather than rely on a dwell meter that might be giving misleading readings, would it be an idea to maybe just set the points to the gap when fully open to that specified in the manual (0.015 inches) with a feeler gauge?
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I always set them using feeler guages, but, as an apprentice I spent hours listening to my mechanic saying "too loose, too tight, too loose, too loose, too tight"......ad infinitum..... :LOL: It probably took two years of suffering that every day before I could actually get them "right" and ever since, and even now, if I check gaps other people have set, most of the time they're wrong.
 
:LOL: One old trick I remember some people swearing by was to use the foil paper from a cigarette packet to set their points gap. I was a Regal man myself.
 
harveyp6 said:
... if I check gaps other people have set, most of the time they're wrong.
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Likely they're right, and HARVEY is wrong! :p (Why do I suddenly feel a nasty electric shock coming over me? :p)

I HATE setting points gaps, I NEVER get it right! :evil: :x :(
 
darth sidious said:
I HATE setting points gaps, I NEVER get it right!
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Because the points are sprung you can't just set the gap by feeling the drag like on a plug gap. You need to feel the drag and at the same time look and check that the contacts don't move apart when the feeler gauge is inserted. Its tricky. You also need to dress the contacts flat first if there is a pip.
 
So two things are happening here, but even when the engine is finally set up correctly,the alternator should be charging at those RPM's and that issue will have to be addressed.
 
OrganDoctor said:
So two things are happening here, but even when the engine is finally set up correctly,the alternator should be charging at those RPM's and that issue will have to be addressed.
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Indeed
none of the ignition setup addresses the problem of the either faulty battery or alternator set up. At RPM's of 650 or more the battery should be charging regardless.

Graeme
 
I have been tinkering a bit more today as I have bought an electronic ignition kit. The kit went together with no bother at all and the car now idles nicely at 750RPM. Now that it is running more smoothly i went over things again with the testtune meter and it still seems to indicate that there is an alternator problem. Volatge on the batery on tickover at 750RPM is now 12.08V. The tusttune indicates that the alternaor is undercharging. At higher rpm, the indication goes up slightly but remains in the red 'undercharging' region. Is there anything i can do to improve the output from the existing alternator or am I going to have to part with some more pennys?
 
Hi Dayle,

An undercharging alternator is usually down to either or both the carbon brushes and the voltage regulator. Both are easy to replace and and are quite inexpensive. I wrote a thread on carbon brush replacement, hence the reason for Dave's suggestion.

viewtopic.php?f=16&t=10203

Ron.
 
I just read your alternator brush replacement thread. It sounds like it might be a rectifier fault. Maybe the brushes too. I'll get them checked out and replaced if need be and let you know.
 
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