Breaking starters?

2 years ago I installed a MSD atomic fuel injection system that controls my timing. ever since then by 455 has been going through starters at an alarming rate (about 7 in that time span) and this includes Jamie's starters (start-n-charge) from this community. can I get some ideas as to why this may be happening? I think that it has to do with my timing, I have my initial timing set at 14 degrees (setting it down to 8 or 10 seems to make no difference). any help would be appreciated.

 

Yes larry. You lock out the distributor, retard it 15 degrees and time it 15 degrees ahead
(Or so thing like that, I did that 2 years ago when Installing it)

 

It almost certainly has to do with the timing. Are you able to datalog timing with the Atomic MSD? And does the timing while running match what is commanded and does it behave like it's supposed to with rpm?

Another test is, disconnect the ignition coil wire, crank the engine and note relatively how quickly(slowly?) the engine turns as well as how it sounds. Then hook up the coil wire and observe the difference. If it is noticeably slower or more labored then it is definitely timing related.

Can you command an even lower cranking rpm? I have both my Skylark and Firebird cranking with 5 of timing. The engines spin like the ignition is off, gets the rpm up to ~300rpm before giving it more timing.

If it's not timing, what is your cylinder cranking compression, as measured with a gauge?


**Edit, to add to it after reading the phasing information, make sure the phasing isn't such that the rotor is allowing spark to jump to the next cylinder. That will hammer starters pretty hard.

 

sorry larry, im not 100% sure what you mean. all the weights and springs are removed from the distributor and you lock out the timing. I installed the adjustable rotor (phaser) and set it to 15 degrees advanced like the instructions say.

silverbuick
I don't think you can datalog I never checked to see if the timing is doing what it's supposed to. how would you do this? hook up a timing light while the car is running and have someone rev the motor while someone watches the light?
how do you check cranking compression?

 

the timing controller is the EFI atomic itself. it has the ability to control the timing.

 

Be careful with electronic timing control with a distributor. You COULD have a rotor phasing issue causing your spark to jump another post on the cap occasionally. This can give you a kick back once in awhile and with these PG260 starters a nice cracked housing. Guess how I know?

Search YouTube for MSD rotor phasing and you will see what I'm talking about. Arbitrarily just setting the phaseable rotor may not have gotten you where you want to be.

And now I see Silverbuick pretty much said all of this earlier.... Sigh...

 

Someone suggested that the rotor was jumping posts to me last year as well and I changed my rotor and cap. So I don't believe that it's a defective cap or rotor. Is there another way that spark can jump posts?

 

Initial timing usually has everything to do with breaking noses on starters.
And its USUALLY the worst on mini starters:eek2:

 

Yes I did. The car runs great and usually starts great. It only has trouble staring sometimes.

 

A datalog, or even being able to watch a readout of commanded timing while cranking would be nice. To check that timing is doing as expected, the controller should have a read out of the timing it's commanding. Such as 20 while idling, then with a dial back light, or if your balancer is marked all the way around, use a timing light to see that you are actually seeing that 20 with the light. Likewise, rev it up some and see that timing advances appropriately. If you can hold it at a steady rpm, like 3,000rpm, and see on the controller that it is commanding something like 38 and verify that with the light as well, then you know it's doing what it's supposed to at two points and that would mean it is very likely doing what is commanded during cranking. Then double check what the commanded spark is for cranking (lower is better IMO) and if you can what RPM threshold it is using to designate a cranking state. Such as 300rpm or less.

Standard compression test. Disable the ignition, pull a spark plug in one of the cylinders, install a compression gauge, hold the throttle WOT and crank for five seconds. If you are seeing over 200psi, that would be part of your cranking difficulty. Depending on the rest of the build, camshaft, static compression, etc, a number between 130-175psi is likely in the normal range.


Triple check the rotor phasing. I'd start with having the rotor dead center for the cranking test. As mentioned, if the rotor is set 15 advanced (clockwise!) it could be jumping spark to the next cylinder in line, doesn't matter how new or old the cap or rotor are if it's set to far advanced.

When I was messing with rotor phasing, I marked the #1 distributor cap post on the distributor base, then using a breaker bar turned the engine clockwise until timing lined up with ~25 (mid point between 5 & 45) and set the rotor to point right at my mark. Alternatively, if you only have the timing tab, turn it to the 10 or 12 mark and set the rotor to just past (clockwise) the mark on the distributor base. Like just the width of the rotor point, and that would get you close to the mid-point of your likely timing sweep. This makes it so anytime you are around 20-30 of ignition timing the rotor and distributor cap tab are near perfectly lined up. When you are WOT at 32-34 it's still mostly lined up and little spark energy is lost, and most of all in your full spark range the rotor is closest to the cylinder that you want to light off.

 

If spark is jumping to different posts, wouldn't it happen all the time, like during regular driving? Why is it only happening during start up?

 

I had this issue years ago and finally fixed it by putting the biggest starter wire on that I could find. A slow crank allows for a lot of "kick back" time. Hope this helps.

Mike

 

Because the timing is (should be?) at it's lowest value during cranking. With low timing values the rotor has more time to pass the distributor cap tab before the spark gets there, so it may be nearer the next cylinder. When timing increases the spark happens sooner, or before the rotor has passed the tab in the distributor cap. If the rotor is phased in the wrong direction this would further compound the problem. For other food for thought, the issue can be compounded if the MSD is issuing multiple sparks as well during this time because of the longer spark duration can bring it over to the next cylinder as well, which is coming up on the compression stroke. This is RPM sensitive, and cranking RPM will vary with battery voltage and engine temperature, so when you end up with a certain battery voltage with a certain engine temperature, the cranking rpms fall into the window of kicking back. Typically the faster the cranking rpm the less likely you are to have a kickback scenario.

 

P.S I went with a much heaven duty starter this time. Not sure if this is a good idea or not. If there is a problem, I'd rather be breaking starters then flywheels/engine blocks.