Why use a distributor?

[DonWG]

I hear of more and more people having to switch to a distributor. What is the reason for it?

[Bent6]

Several reasons - stronger spark, eliminates the stock waste spark, and 50-75 more hp - probably due to the stronger spark and more accurate timing. Some will tell you that making the switch to a distributor is necessary once in the low 9sec to high 8sec zone and that the stock Buick DIS ignition can't take you any further - BS. My car has gone 7s many times with the stock Buick ignition. The main reason for me switching to the distributor after all these years was to get a good strong tach signal for my electronics, increased timing accuracy, and so I wouldn't always be looking over my shoulder waiting on the stock coilpack to fail.

[turbodragster]

i have never run anything but a distributor but i think its just a whole lot simpler to run just my opinion.

[DonWG]

It seems like such a backwards move to me. If there was a problem with running the XFI system in a wastespark configuration, not a strong enough spark, then I could understand. Even then, it would seem like a bandaid fix. But, if the wastespark was doing fine and you added the extra components to go back to a distributor setup. That makes no sense to me. The short comings of a distributor are well known. Has technology changed that much in a distributor that it is now preferred over the simpler and more accurate wastespark? Why haven't OEMs gone back to distributors? It would seem to me that if there was any advantage to going back to the days of distributors, the OEMs would be all over it. Trying to understand this. Is it just a nostalgic fad?

[Bent6]

Make no mistake, the stock Buick DIS ignition is very good despite what many say - my car has been 7's many times with a completely stock ignition. It's not a matter of incompatability but rather the limitations in efficiency of the stock DIS system. It's not an old school distributor in the sense you are thinking. The internals of the distributor are removed for the most part. The only function of the distributor in this setup is to provide the ECM with a cam sync signal and to distribute the spark when fired by the coil.

While some people still use the stock crank postition sensor with the distributor setup, the stock steel reluctor wheel can be off as much as 4 degrees. The best way to go is with a flying magnet setup along with the distributor for dead on timing accuracy. Think of it as a glorified cam sensor with the coilpack built in as one unit. I leave for Bowling Green in the morning. I'll let you know how I like the "old school" distributor setup.

[DonWG]

You can't get dead on accuracy from a distributor signal or cam sensor signal. Especially if you're using a timing chain and not a gearset. A timing chain goes sloppy real quick, forcing you to periodically check and adjust the sync adjustment. The only way to get dead on accuracy is with a high resolution crank trigger wheel signal only. Nothing can change on you from wear with that setup.

What do people do about the resistance that builds up inside the cap? Do people have to perform maintenance on the contacts in the cap and the rotor tip? I would guess that with high energy setups those would deteriorate quickly. I used to change a lot of caps and rotors in the 70s at the service station. I remember when I used to race with points and condensers and would get the small points file out and pop the cap and rotor to clean the contacts to keep resistance down. Maybe the high energy stuff just blows through that build up now. Seems much more efficient to not have to deal with that extra gap. I'm sure the extra gap doesn't add anything to the performance of the ignition system.

[DonWG]

It would seem to me that if there's anything to be gained from the xfi, distributor, msd arrangement, it's going to be due to the msd box. Certainly not because of the distributor. If that's the case, then why not just go with a DIS system that gives a hotter, longer spark? Now you're just going to add cap and rotor wear to your tuneup list, and have to periodically check for distributor gear and shaft bushing and endplay wear. A few more points to add to the inaccuracies of a distributor system.

[Bent6]

Donnie - you may be reading into this "distributor" thing a little too much. You can't compare what we are talking about to points and condensor distributors from the past. The DIS stuff MSD put out a few years ago for use with the stock coil pack is total JUNK - ask anyone who had one. I realize a timing chain stretches, tolerences change, etc. The distributor is more accurate because of the flying magnet setup. The real advantage is in the MSD box not the distributor like you said. The only distributor setups I know of are on race only cars so I don't think the issues of corrosion, etc are that big of an issue. Stock cam sensors have bushings that can wear and a drive gear as well so what's the difference there? I don't know of any low maintenance race cars anyway

[BAGN]

Originally Posted by Bent6

I don't know of any low maintenance race cars anyway

I dont know of any low maintenance BUICKS!!!

[DonWG]

I'm aware that you can't compare points and condensers to high energy ignitions. The point I was trying to make was that if you ever raced with points and condensers you learned to become very aware of each and every short coming of the ignition system. It was one of the systems that required the most attention if you wanted top notch performance. You couldn't get away with ignoring the ignition system.

There are other ignition suppliers other than just MSD and stock.

How much does a MSD cap and rotor go for?

[DonWG]

Originally Posted by Bent6

Stock cam sensors have bushings that can wear and a drive gear as well so what's the difference there?

That's exactly the point. There is no difference. They're both a sloppy way to sync.

[DonWG]

Originally Posted by BAGN

I dont know of any low maintenance BUICKS!!!

Ain't that the truth! But why make it harder?

[Bent6]

Originally Posted by BAGN

I dont know of any low maintenance BUICKS!!!

[turbodragster]

msd dis dosent make as hot a spark as an msd 8 i can tell you that.

[turbodragster]

you need to use whats best for your application. the DIS in some cases is not enough spark.

[Ted A.]

Don, the MSD crank trigger wheel (flying magnet) is attached to the crank direct. No timing chain will effect this. The cam sync only give the ecu a reference to the firing order so it can sync the injectors and individual timing. The rotor phase may be a little off because of timing chain flex, but the accuracy of the spark will not be effected.

If you don't have any distributor stuff, I would run the COP setup with a 24x wheel not the 3 pulse/revolution setup.

[DonWG]

Originally Posted by turbodragster

you need to use whats best for your application. the DIS in some cases is not enough spark.

What DIS configurations are you familiar with?

[DonWG]

Originally Posted by Ted A.

Don, the MSD crank trigger wheel (flying magnet) is attached to the crank direct. No timing chain will effect this. The cam sync only give the ecu a reference to the firing order so it can sync the injectors and individual timing. The rotor phase may be a little off because of timing chain flex, but the accuracy of the spark will not be effected.

If you don't have any distributor stuff, I would run the COP setup with a 24x wheel not the 3 pulse/revolution setup.

I agree. The 3 pulse per revolution is not adequate.

I have to disagree with the cam sync having 'no' effect on spark timing accuracy.

A high res, crank mounted timing wheel with the sync built into the crank wheel can't be beat.

[Ted A.]

Don, at least speaking for BS3, the ECU does not use cam sync to calculate spark timing.