What's The Point?

Three words: PER EFFING TRONIX.

 

But why would the timing jump around at idle? And why does centrifugal advance not do as much as vacuum advance? And shouldn't the breaker plate be less floppy? I am starting to wonder about the quality of the remanufactured distributor. And it seems that if those things are wrong,a Pertronix unit wouldn't solve the problem. Not to mention the carb spacer possibility...

 

The inherent design of the Ford points distributors leave a lot to be desired. However, mechanical advance is not supposed to impart that much advance (in relation to the base timing), so that I would not worry about. It's the loosening of the internal components that make me say take the Pertronix plunge. Hell, if there's a Duraspark II dizzy from 335-series engine that would fit, put that in, and I'll ship you a usable DS II harness to wire it in. All you provide is the DS II coil and module. It's the least I can do in return for that code reader. You might have to have someone curve the dizzy to match the cam grind, plugs and carb, but it'll give you peace of mind.

 

So anyway, the '73 400,as I may have mentioned,runs roughly especially at 45-50 mph at light throttle. Idle is not the smoothest,but livable. Acceleration is good. I got a vacuum gauge and the engine tests OK. The sticker on the engine says 12B,the manual says 6B. My guess is that this was changed during MY 1973 for Federal reasons. So today I set the timing at 6B. Acceleration is much stronger,and the roughness on cruise is less,but still there. I also cranked the idle down to 625 rpm,which is where it is supposed to be. Points at 17,dwell at 25. Aaah,what does it all mean?

 

It means you have to play f%&karound with it all the time. Go get a Pertronix II and a Blaster coil. Follow the instructions, and enjoy not having to make adjustments.
It is true that when Federal emission guidelines hit, both ignition and cam timing had to be retarded, but it was coupled with electronic ignition and a wider spark plug gap on a slightly hotter plug. Then the carburetors were dialed back to bring MPG up and emissions down.

 

>>Points at 17,dwell at 25. Aaah,what does it all mean

I doubt that this will cure your problem, but why are you running your point gap so tight? Your dwell should be between 28 - 32 and is normally set at 30. It should be set by grounding the coil wire and having someone crank the engine over while you adjust it. Dwell allows coil saturation between cylinder firings. Low dwell results in a weaker spark. Reset your dwell and then reset your timing at the recommended rpm with the recommended vacuum lines disconnected and plugged. If it's idling to fast when you adjust your timing, your centrifical advance will be engaged to a small amount and you will actually be retarding your timing if you set it at faster than the recommended rpm.

 

Thank you, Old Fox. I think my skill set is getting way too dulled and I should've picked up on the dwell setting. Having said that, I would like to see Slidemanic change over to electronic ignition.

 

The dwell setting may be 24-32, but you always want it at 30 for the highest coil charge time and closest correct initial timing.

 

"You can lead a horse to water but you can't make him drink"
When I buy a car with breaker points ignition it's the first thing I toss.

 

Your skill set is to modern these systems worked for years and are very simple. Most problems is from overthinking and not knowing the old system. Carb , timing , dizzy all have to be considered when adjustments are made just as Old Fox says. I have my brothers Merc 400 with points set up running like it should.

 

I don't know if you are referring to me or the original thread poster, but yes, for when that was properly maintained by someone who knew what they were doing (and I learned from a former Army helo mechanic), your vehicle ran reasonably well. However, technology to reduce or eliminate d!cking around with such a device because it controlled the coil charging made for a lot of gnashing of teeth and wailing "I have to learn something new!" But you know? The best of the best of techs always hunger to learn what's new and keep up with it. I've done point-condenser maintenance and adjustment, and it's, meh. The best thing to say about it is that it's a pain in the @$$. I would rather deal with a setup that has the fewest adjustments and the most mileage between maintenance intervals. And no, I am not a parts replacer. I diagnose to the errant or dead part before replacement.

 

OK,Old Fox,that sounds great,but I do not understand "Grounding the coil wire". And how am I setting dwell while my assistant cranks the engine?

 

Sorry, forgot you are doing a GM and I had Ford on my mind. You can adjust it with the engine idling thru the port hole in the dist. cap. Hook up your dwell meter and insert your allen wrench into the points. Start the vehicle and turn the screw until you get 30 degrees. How have you been doing it?

 

I thought he was working on a Ford 400 cu. in. I didn't mean to ruffle winkiehobo's feathers but I have I have been certified in auto and diesel mechanics since the 60's and my last training in 2014 before retirement. I think that when you have an older car you need to stick to basics before throwing money on a problem. Compression testing for valve-train problems, vacuum problems , and proper adjustments. Have done the duraspark conversion a few times and pertronics but if module goes you are dead in the water . Original poster has had these problems for quite some time and needs to rethink his problem. The one problem that happens with this car is the plate between carb and manifold can make adjustments hard to hold which was already mentioned. This is just an opinion to help out without chasing a minor problem with a fat wallet. We are all here to help each other and sometimes hard to do. on the internet.

 

In this thread, I had Slidemanic go back to basics because he was all over the map with his problem. There were other underlying issues (which possibly are not yet fully fixed), but anytime a member is flailing at a symptom and getting nowhere, I always suggest going back to basics or follow the factory diagnostic method.