Tune up

[Ctmangrum]

How often are you guys generally doing a full tune up? Not just changing the oil and fuel filters? Impellers, spark plugs, distributors, etc? Thanks

[km1125]

I started doing them every few (3-4) years, except for the impellers. I would not consider impellers a "tune up" item, and their life is largely determined by how you run them. If you run them dry or in water that has a lot of floating debris (cloudy water) then their life can be short. If you're in very clean water then you can get several years out of them, BUT since they're a relatively cheap item and can ruin an otherwise-perfectly good weekend, I would change them much earlier than you HAVE to.

Plugs I just do an inspection every couple years, which could be a couple hundred hours. This is more to make sure they don't seize in place, which is a bigger problem. If the engine is running right (not to rich or lean) and doesn't overheat, they can last a good long time. I switched out to an electronic ignition early in my ownership, so the points and condensor thing went away, but points and timing should definitely be checked annually if you're still running them. It's easy to inspect the cap and rotor and replace when they're getting worn - I've easily had them last 10 years.

[Ctmangrum]

That was my next question. First time dealing with points and was considering switching to electronic ignition. Complicated process?

[km1125]

Source of the post That was my next question. First time dealing with points and was considering switching to electronic ignition. Complicated process?

It's been years, but on mine it was very simple. The new system came as a "kit" with the distributor, cap and new coil. Remove the old stuff, put in the new stuff and set the timing. The new system no longer used a ballast resistor, so you just capped off that line. I think the whole kit for mine was $275/engine but that was a long time ago.

Points do work fine but they are a maintenance item much more than anything else in the ignition system. At high RPMs you're using the points a lot, vs on a car where you rarely run long-term at high RPMs. Even then, on a car, you would be tending to the points annually.

[Ctmangrum]

So i went to order a conversion kit and nobody can determine what part i needed. I only know it currently has a screw down cap on a 1976 Ford 351 mercruiser 233.

[tomschauer]

There really is nothing wrong with points if you know how to set the dwell angle properly. especially on a boat that only sees a few hours of use a year.
New plugs, wires, points and distributor cap, with dwell and timing set properly, you should be good for a couple years.
If you really want to switch to electronic ignition, that engine is I believe is a 351M, the same as any ford pickup of the same model year.

[km1125]

Nothing wrong with points and they are simple but they are a maintenance item.

But just some perspective...

Consider that for each time any individual spark plug fires, the points have to 'fire' too, so on an 8cyl engine the points 'fire' 8 times more than any individual plug. Every single spark plug and every cylinder depends on the points to 'fire'. At 3000 RPMs, the points need to 'fire' 720,000 times for every single hour you run the engine.

Points also determine timing and dwell (the time the coils gets to recharge before it needs to discharge for the next cycle). A little bit of wear can vary both of these items, and you typically won't notice changes unless you either try to measure them or they get so far out of spec that things aren't running right and you waste a good weekend when yo could be on the water.

[tomschauer]

KM, I am a big fan of electronic ignition, I no longer own any points cars, trucks or boats. But I must say, points may degrade over time and cause a rough running or missing engine, but they keep going. When your electronic ignition module fails, it fails. You aren't going anywhere.

[bud37]

Yup and with a small file and a matchbook cover you are back in business.....

[km1125]

Source of the post KM, I am a big fan of electronic ignition, I no longer own any points cars, trucks or boats. But I must say, points may degrade over time and cause a rough running or missing engine, but they keep going. When your electronic ignition module fails, it fails. You aren't going anywhere.

Yep, I would agree with that. Luckily the ignition modules have improved greatly since their introductions back in the 70's and 80's.

When I upgraded my points systems to electronic ignition distributors back in the early 90's, I still kept one of the points distributors on the boat for YEARS just in case I had a failure. I think I finally removed it after about 5 or 6 years.