distributor To EI or not

[BadaBing]

I have previously mentioned my wish and intention to upgrade (?) My ignition system to electronic ignition. My reasoning being that " newer is better" After exchanging ideas online with some.of you and talking to Mr Moyer I have put this off over the past couple of years because my distributed cam lobes seem ok and changing points every year, if necessary, is not a big deal.

We put the boat on the hard this winter so we could have our bulkhead repaired, hurricane Sandy almost did it it. This was a big expense that we had to just suck.up.

For something to do I removed the carb and distributor and brought them home to my work bench to spiffy them up, and reinstall in the spring. Thinking again of the EI option.

A careful examination of distributor cam shows no visible sign, that I can see, of the cams being worn down. I would guess that IF there was wear that it would be inconsistent up and down, as the contact for the.points is smaller than the cam itself, and possible inconsistent from lobe to lobe. So my first question.
Other than a visual inspection are there any published numbers or measurements that could.be used to determine the condition of the cam lobes?

It sounds to me that the downside of worn cam lobes is the altering of the dwell. Honestly I have never checked my dwell just setting the point gap and adjusting the timing by ear as per the MM manual has always seemed very adaquet. The winter days give me to much time to dwell on things like dwell, so I am wondering about the effects of dwell on an engine performance.

It seems to me that it is.possible to have point gap adjusted properly and to still have the dwell out of wack.

Reliability s.#1 for me, performance a close second (more hand in hand) what effect does dwell have ? Please feel free to just point me at an existing thread.

Along the same thinking I found my centrifugal advance weights very rusty and very possibly not advancing as freely as they should. I took it all apart, polished the weights and oiled them up. How much advance should the A4 realize as the rpms go up?
Bill

[hanleyclifford]

For purposes of the Atomic 4 there is no performance advantage to switching to EI. The primary reasons for doing so are reliability and almost maintenance free operation. Another reason which necessitates EI is the wearing of the lobes as you describe. As the lobes wear an ever smaller point gap is required to achieve specified dwell. There is no thresh hold for this but I would suggest that if you need to go as low as .012" point gap you should get another distributor or go to EI. The EI will give you around 55 degrees, way above the stock 31-34. This means you must protect the coil from high voltage (and amperage). But that is another story. BTW, the theoretical total advance provided centrifugally is 34 at the crank or 17 at the distributor (also another story).

[Mermaidquest]

I LOVE my EI

I have EI petronix in my 1971 A-4 and it is hassle free.I wondered for a year why the blasted thing ran so well untill I just HAD TO REMOVE THE DISTRIBUTOR to drill and tap the top row of water-jacket cover bolts. And then Behold-EI.

[ndutton]

what effect does dwell have?

Dwell affects coil saturation, coil saturation affects spark quality. Too little saturation and you'll have a wimpy spark, too much and you risk overheating the coil causing irreparable damage.

EI offers greater coil saturation compared to points and eliminates the need for points+condenser replacement.

[romantic comedy]

How do we check the dist lobes? a dist machine?

[ndutton]

Without specifications available a poor man's test apparatus would be to carefully set the gap, then measure dwell. If both meet spec within reason you're good. If not, lobe wear is indicated.

[JOHN COOKSON]

Without specifications available a poor man's test apparatus would be to carefully set the gap, then measure dwell. If both meet spec within reason you're good. If not, lobe wear is indicated.

Before you do all this check the rubbing block (where the points contact the distributor cam) for wear. If there is any doubt check the rubbing block on the old set on points against a new set.

TRUE GRIT

[jbsoukup]

for me the switch to EI in my A4was a no brainer, having switched a number of motorcycles in the past. It's set it and forget it, performance will not change over time. I just changed my distributer cap and rotor last spring after 9 years, just as a precaution, not because it was bad (it was starting to look a little worn). Just make sure to get a new/modern coil at the same time, to avoid a failure.
And just to be clear, I often fish (troll) under power on calm days for hours at a time, year after year and have had no trouble with my ignition system.
No maintenance either.

[Dave Neptune]

Bill, the A-4 calls for 17* advance via the centrifugal system. It should be fully advanced by 1800. You can check this with a timing light and a marker.

Go for the E/I and be done with it.

Once the cam lobes are worn enough that the gap setting causes "more dwell" than the prescribed dwell the cam is shot!

Dave Neptune

[sastanley]

When I switched to EI, one of the things I forgot about was you still need to periodically maintain the advance weights. Mine were so stuck after 5 years that the engine barely ran. An old Harley guy asked me about it and the light bulb went on over my head.. She's been running great ever since I fixed that up in Cambridge this summer (while we visited with PT26 )

[BadaBing]

Just for the fun of it. IF the centrifugal advance was not advancing or only partly advancing, what would the symptoms be? Lack or rpm under power? As in only being able to run up to 1800 or there about? A loss of power as th engine attempt to ramp up?

[Dave Neptune]

Bill, if the timing was set "properly" and the advance starts sticking you can loose power if it does not advance all the way and a poor idle if it is stuck too advanced.

Dave Neptune

[BadaBing]

Dave Thanks.
I thought so but wanted to check
,

[Renegade]

EI

I changed to EI, the Moyer coil and Autolight 86 plugs a few years ago and my 1974 engine runs like a top. My question is how often should the rotor and cap be replaced? I'm in freshwater so saltwater corrosion is not an issue.

[Dave Neptune]

Renegade, refreshing the cap rotor every 4~5 years should be fine. And do keep a check on the wires. My plugs go for around 3~4 years too. When I do change the "STOCK" plugs out I do not see any gain other than maybe a bit silkier running.
Note take advantage of the EI by opening up the plug gap a bit .040/.045 will work fine on the top end and idle much smoother too.

Dave Neptune