Distributor Timing Problem

[Stuart F.]

Re: Distributor Timing Problem

OK. Thanks for all the tips.

Joe, I retained the original shaft because the scratch damage was above the position of the lower bearing, and the play in the bearings was minimal, barely detectable. The project started out as a rebuild, but became more of a refurbish. The main improvement was with the cross shaft. I drilled, tapped and installed a set screw to limit the cross shaft travel as it had already bored a fairly deep hole into the housing. There too, I reused the original cross shaft to maintain the gear match to the original shaft, and because the end was hard steel. The new replacement I had gotten had a bronze end which I figured the set screw would chew up in no time. I sent all the new internal parts back for these reasons and my conclusion their quality was sub par. I could not use the bronze or Teflon buttons either as I didn't know of a shop that I could trust to counter bore the housing to fit them with the cross shaft.

Steve, I have a Pertronics II conversion and, no matter what, I swear by it. My life has been so much better without points. My breaker plate is a Dyna-Flyte ball bearing unit which I've used for over 20 years. The VAC can is a B28, the performance of which I check regularly with my Mityvac. I have had it in use for about 4 years now. I did not change it. The only thing I changed on the top end was the advance restrictor. The old one had a groove worn into it. I also added an "E" clip. I used a lot of recommended silicone grease on the reassembly of the shaft and for the top bearing. I did close up the gap tolerance of the Pertronics magnetic pickup, as well as the end gear (as previously noted), neither of which should affect the timing that I know of.

After I change out my carb this morning, I intend to pull the distributor and rotate the gear (gosh, I hate to do that).

Thanks for the help guys. I'll report back how it goes. To think all I originally wanted to do was just change my plug wire brackets back to the originals in an attempt to get easier removal/replacement of my top ignition shield cover, and all this happened (distributor and carburetor problems).

Stu Fox

[Timothy B.]

Re: Distributor Timing Problem

Stu,

Two things come to mind, one is a advance restrictor if it has anything to do with moving either the points plate or the at rest position of the mainshaft.

The second is the gap on the Petronics, I don't know much about them but could this have cause the module to fire differently than before.

[Steve G.]

Re: Distributor Timing Problem

Stu,
Wasn't suggesting going back to points, thought you might still have them. Nothing wrong with a Petronix conversions.

Puzzling as to what changed. You have the same shaft with the same gear indexed the same way and sitting in the same housing. If it's engaged in the same gear on the cam why is it firing at a different time?

The only possibilities are the breaker plate and the relucter wheel. I'm not familiar with an advance limiter. In the oe design mechanical advance is limited by the pin and slot arrangement between shaft and cam body. Breaker plate initial position and max travel is set by the advance unit's mounting and linkage rod.

Can the Petronix relucter wheel body be installed 180 degrees off? That would have the same effect as having the gear 180 off on the shaft.

Steve

[Gene M.]

Re: Distributor Timing Problem

I have no idea where in degrees the pertronics position is compared to the points. That is to say were in degrees difference do it position #1 firing compared to the position of points at #1 fire. Is it possible there could be 20 degrees difference?

Does everything work out if you put the points back in?

[Steve G.]

Re: Distributor Timing Problem

I have no idea where in degrees the pertronics position is compared to the points. That is to say were in degrees difference do it position #1 firing compared to the position of points at #1 fire. Is it possible there could be 20 degrees difference?

Does everything work out if you put the points back in?

I think he said the Petronix was a long ago installation and everything aligned with it until he pulled it apart this time.

Might be simply getting ahead of ourselves here. If just going by the visual on where the rotor is pointing without referencing the actual firing there may not even be a problem. There's probably 20 degrees of rotation range the rotor can reach the cap. I don't know at what precise position reluctor and pickup fire on the Petronix, but without that information you need to use a timing light to know where you are.

Steve

[Joe C.]

Re: Distributor Timing Problem

Reason I asked about the main shaft is because the clocking of the "football" determines the rotor position. Depending on how well made it is, the clocking might have been off. But, alas, that is a mute pernt in dis case.

If your main shaft had a lot of end play in it before, and you shimmed it to the proper end play (.008, although I like to shim it to .002-.004), then that will affect the rotor clocking as well. In any case, rotating the driven gear is perfectly OK. If you replaced the driven gear, then worn teeth on the old gear would also re-clock the rotor with a fresh gear.

Vertical clearance with a Pertronix has nothing to do with timing.

[Stuart F.]

Re: Distributor Timing Problem

Tim, Gene and Steve;

Some very good points all.

The advance restrictor (limiter) sleeve is merely that which goes over the pin which fits in the slot. We are all familiar with it I'm sure. I just replaced mine with a new one as the old one had sort of a groove worn into it and was also looking brittle. I added the "E" clip on the bottom of the pin as I never had one there and as long as the groove exists figured I might as well use it (a non issue). My plan was to use my degreed tape and old fashioned timing light to adjust my total advance again. I did it once before when I still had access to a distributor machine.

Note: I'm still looking for a reasonably priced dial back timing light. If I'm lucky, I may be able to use it a couple of times before my son inherits it.

I will look closely at my Pertronics pickup for gap and positioning. It will normally only fit in one location with a two hole screw lock down (no slotted holes or adjustment), and that's the way mine is installed. I did pull my top bearing up just a micro amount so that the wave (lock) spring would hold the center portion of my Dyna-flyte plate in place better. Only the outer portion of the plate rotates in the ball bearings. This too should be a non issue as it might only close up the pickup gap be a few thousands. When I checked the gap during assembly it was well within Pertronics minimum tolerance, but I will check it again tomorrow when I pull it again (today was carburetor repair day).

Stu Fox

[Duke W.]

Re: Distributor Timing Problem

Ed;

During the re-build of the distributor, I did put on a new drive gear, but changed back to the original on advice from others on the TDB to not mess with the wear match. I checked that again today to ensure that is what I did (trying to cover all bases).

Stu Fox

Does the replacment gear have a dimple? I've heard that some don't, which is another reason not to use them unless the original gear is obviously damaged.

BTW, the rotor always points approximately at a cap terminal when the plug fires. This may not seem obvious because you can turn the rotor by hand, but what happens in the operating engine is that the cam assembly, which holds the rotor rotates CCW in response to the centrifugal advance, which advances both the spark timing and rotor. VAC movement does move the rotor relative to the cap, so with a 16 degree VAC rotor-cap indexing will vary over an eight degree range, and changes in initial timing will alter rotor-cap indexing by one degree for every two degrees initial timing change.

Duke

[Gene M.]

Re: Distributor Timing Problem

Stu,
I just thought of this. Is the dot marking on both gears in the same spot in relation to the gear teeth and roots. The 13 tooth helix gear yields 27.5 degree or approx. 14 degree difference if one is aligned with the tip of the teeth vs the root of the tooth. Just a thought but visual if different.

[Joe C.]

Re: Distributor Timing Problem

New IRON gears, as original, have the dimple in the same place as it always was.
New MELONIZED STEEL gears have the dimple located in a different place. If Stu used a new, steel gear (and I hope that he didn't if he has a non-hardened iron camshaft), then the new dimple orientation is very apparent because it's re-clocked at least 20 degrees from the old iron gear. In any case, there's no way to get it aligned with the rotor tip as he indicated that he had done in an earlier post.

[Stuart F.]

Re: Distributor Timing Problem

Duke, Gene and Joe;

Thanks for your valuable comments. Glad we found a subject we can all chew on for a bit. Discussions have been pretty lean of late in the mechanical field.

I am using the same original distributor and tach cross shaft drive gears. The only change is in the end clearance of the drive gear which I tightened up to .010" from what was something close to .020". I would have tightened it up more but did not have a good shim mix. I don't like to use more than two shims, and none too thin. The cross shaft gear is now positioned by a set screw, so should be in a better more centered engagement with the shaft gear. Probably a moot point.

After I get a working carb back on the engine tomorrow, I intend to pull the distributor to recheck everything again. Then, if frustration gets the best of me, I will probably repin the drive gear with the dimple 180 degrees ( boy, I hate to do that.

Just another point; I even considered my timing chain may have jumped a tooth (not hardly), but I know better and I recall putting on a new set of sprockets and chain back in 92. The reason? I had them and I had the pan dropped to knock out a dent and replace a bad drain plug fitting.

Thanks again guys.

This last comment is for Duke to see if he's read this post through; Duke, do you get "Trains" magazine? If so, there's an article about the Tier 4 567, 645 and 710 engine series demise. It was written by an old EMD friend of mine "Bill Badersky". It certainly pounds the last nail in my Tech Writing career. Yes, I did write the first "H" engine service manuals, but I never felt as intimate with that engine as I did with the old two cycle. I'll send you a copy of the article.

Stu Fox

[Gene M.]

Re: Distributor Timing Problem

Stu,
I have one last thought (then I think my quota is up). Are you running solid core wires? I had an issue with a one timing light that didn't like the solid core wires. It gave me way out in left field indication. Had to go get the old reliable one out.

[Duke W.]

Re: Distributor Timing Problem

Duke, Gene and Joe;


This last comment is for Duke to see if he's read this post through; Duke, do you get "Trains" magazine? If so, there's an article about the Tier 4 567, 645 and 710 engine series demise. It was written by an old EMD friend of mine "Bill Badersky". It certainly pounds the last nail in my Tech Writing career. Yes, I did write the first "H" engine service manuals, but I never felt as intimate with that engine as I did with the old two cycle. I'll send you a copy of the article.

Stu Fox

My understanding it that Cat stopped locomotive engine production after December 31 last year because the new design that meets Tier 4 emissions (required as of Jan, 1, 2015) will not be ready for production for at least another 12-18 months. I think it's been known for some time that the classic EMD two-stroke would die with Tier 4. I also understand that both EMD and GE did a land office business last year because the Tier 4 engines are more expensive, and as of now GE is the only choice in a Tier 4 locomotive until EMD gets back in production with their new Tier 4 compliant engine... too bad because EMD's 16-cylinder two-strokes sure sound a lot better than GE's 12-cylinder four-strokes - like comparing a F1 engine to an old 4-cylinder tractor engine, but the old EMDs should be around for at least another 15 years in declining numbers.

LA's Metrolink commuter system is the lead customer for EMD's new passenger locomotive, but first examples are probably at least three years out.

BTW, per my previous post does the replacement gear you bought had a dimple and does it line up with the gear teeth same as the original. Who is the manufacturer?

I don't get "Trains", so I look forward to you sending the me the article.

Duke

[Stuart F.]

Re: Distributor Timing Problem

Duke;

I'll shoot you the article shortly as soon as I find my cheat sheet with your E mail address (I have it here).

The drive gear I have came on an aluminum replacement distributor I bought back in the 70's or 80's when I was turning over GM company cars for me or my kids and thought I needed a spare as I had a failure. It's just generic. The gear appears to be exactly the same as the one on my Vette, just not run in yet. It HAS the dimple. I might have used the gear had not I been cautioned on the TDC that I might better stick with a run in gear that matched my cam gear.

Gene; my plug wires are exact replacements that I bought from Lectric Limited back about 10 years ago. They have worked fine. My timing light, believe it or not, is a great big heavy chrome unit I bought many years ago from Montgomery Wards. I use an in line connection to either the #1 plug or the #1 terminal on the distributor cap. The only problem is I don't see so well any more so the white light works good, but the plug input wires has some breaks in it. Every now and then I catch a good hot jolt which tests my heart to see if it's still ticking. A mini defirbulator, or what ever they call it.

Stu Fox

[Stuart F.]

Re: Distributor Timing Problem

Rotated the drive gear 180 degrees (dimple in the back) and, crazy as it sounds, I achieved 90% of my objectives. I was able set initial timing @ 12 degrees. However, to do this my VAC is tight against the intake manifold. I don't like this, but it runs well. I also checked my total @ 3000 rpm and it clocks in @ 36 degrees. I also had to fix my carb too as it had a float hang up during my failed testing a few days ago. I changed back to my set of modified floats with Tomco inlet valves instead of needle/seats. This allowed me to drop my float levels down another 1/16" to further avoid hot soak drip (wife still complaining about stink in garage). The carb, my 3461S AFB in this case, had been seeping fuel onto the intake manifold below the secondary throttle shaft on the passenger side for some time. This was the same float that hung up. I found the level of fuel inside that chamber to be about a 1/4" higher than on the driver's side.

Oddly, during my initial start up yesterday, I had my VAC disconnected using that line for my vacuum gauge. Then, in order to set my timing at 750 rpm, I had to add more throttle opening with the idle screw and also had to enrichen my mixture screws to get at least 12" of vacuum. Upon shut down, I had a bad case of dieseling which I Cappedi off with my hands on the carb in order to stop the engine. Then, after reconnecting the VAC, I had to reverse my settings of both idle set screw and emulsion screws to finally achieve a good steady idle @ 750 rpm and vacuum up to 14" Hg.

The engine seems none the worse for wear through all these set up problems (typical Chevy V8), including several pops through the carb, and now it just needs a good couple of runs ups to redline (or 5500 rpm to save the rods) on the road to clean her out. That's the great thing about my electronic ignition; it WILL clean the plugs out!

Thanks to all for your great advice and suggestions. They helped a lot. Today is a good day to drop the top for the summer and go for a ride.
Yee Ha!!

Stu Fox

p.s. Duke, having trouble sending the Trains article. Our Gmail says it's still trying. Trouble is on our end with our server. Phone service and Internet have been interrupted the last few days off and on. Must be solar activity.