Starter Issues

[PaulProe]

I am having some starter issues and it is compounded by not knowing the best terminology to use the search function on the forum.

I am running a PowerMaster 9606 starter on a 468 Shelby Aluminum block in a replica cobra. Battery in the trunk, #2 cables to the starter. Fuel injected EightStack, the timing is held at 12 degrees until the motor is started and gone 100revs, then it switches to ECU Timing control at about 14 degrees, minimum. 10.5:1 Compression.

When I start the engine, it loads (lugs) real hard for the first few revs before the torque of the starter takes over and starts to spin the engine. Sometimes it almost stalls before it turns over freely. Occasionally I get a 'bump-back' as if a cylinder fired and pushed back before TDC.

Engine temperature doesn't seem to be a factor. I seems to operate the same whether Cold, Warm or Hot.

At PRI, I spoke to PowerMaster and got nowhere. They said their 9406 was the way to go but I honestly don't think the guy knew much about his products. The 9406 has 250ft/lbs, the 9406 has 180. The 9406 is considerably stronger than a stock starter which many similar builds get by with.

The bump back almost seems timing-related but I can't imagine 12 degrees causing this. Cross-fire maybe?

Open to any ideas on where to begin.

Paul

[jayb]

Some MSD ignitions provide a 20 degree start retard that lasts until the engine reaches around 400 RPM.  I think further retarding the ignition during starting might provide a significant benefit in your case.  A 2 degree start retard isn't very much...

[My427stang]

A starter can pull a lot of power. 

Some idea generation.

- Check to see that the ground wire has a good solid connection to the frame, and the frame to block is just as big
- 2 gauge can be on the small side, but should work if all cables are adequately sized
- Cobras are easy on batteries away from heat, but the longer the cables and older a batter get, you may be just asking too much or tired battery
- Verify your balancer is right and telling you the tight things
- Make sure you go through the setup for your distributor to make indicated and commanded timing the same, usually though a laptop or handheld and verified with a light
- Starters can fail or be made incorrectly, maybe see if you can send back for testing
- Check firing order (a reach because I think you'd notice it running)
- If more start retard capable, add it, won't hurt anything

I know on my ERA Cobra the negative cable design is a little crappy, however, with a good battery that starter should have no issues even up to 18 degrees or so

[Rory428]

Be interesting to hear what happens if you disable the ignition system, and see how the engine cranks without any spark. Should help determine if it is in the starting system, or due to ignition.

[GerryP]

Be interesting to hear what happens if you disable the ignition system, and see how the engine cranks without any spark. Should help determine if it is in the starting system, or due to ignition.

A common fix for this is to use a kill switch that turns off the ignition until the starter is at cranking speed, then flip the switch to start.  But your suggestion is good troubleshooting advice.