Engine kicking back while starting.

I have a 523 ci 4.3" stroke, .040" over with flat tops and P-51 heads.  I have the timing locked at 32 degrees with an MSD 6AL and start retard box.  If I try starting it with the ignition on some times it will kick back and even backfire through the carb.  I started spinning the engine over with the starter button and then turning the ignition on and that works, but it doesn't seem like I should have to do that.  This weekend I had a brain fart and turned the ignition on first.  It kicked back and knocked 3 teeth off my flexplate.  After inspecting it I noticed  5 other teeth that had been previously knocked off.  I replaced the flexplate and starter gear this week so I don't want that to happen again.  I'm OK with spinning the engine first but it doesn't seem like anyone else at the track has to do that.  Does anyone else have this issue?  I have a Powermaster Ultratorque starter.

Mike,

Something about your rotor phasing is off. The problem is that your MSD has a built in 20* cranking retard, and unless you have defeated that, your spark is going to the wrong post in your distributor cap. Thus the backfires. Pull your distributor and check for ionization and carbon tracking inside the cap. Clean everything, maybe a new cap and rotor, and get number one marked and put your distributor back in. The leading edge of the rotor, should be at the leading edge of the post in the cap, at 30* BTDC. Then of course reset your timing with a light, but if you crank the distributor around quite a bit, then your rotor phasing will be off again.

Charlie

Thats more timing than i ran with my p-51 's , but its pretty common to get it spinning and hit the switch with race engines . Are you using a crank trigger ?

No crank trigger just an MSD billet distributor with locked out mechanical advance.

There is always the possibility your "zero" is off on your balancer if it was not verified when the engine was built , not sure what dampner etc your running , example balancer ring could have slipped and timing could be off . Kick back can be from too much timing , weak battery ,weak starter , or rotor phasing if running crank trigger , plus you never know what electronics can do such as a start retard if the polarity is switched you change boxes etc your timing can change.

I always ran about 28 total timimg with my p-51s , but there is just no subsitute for learning to read your plugs . Timimg lights can vary etc.

I'd disconnect the start retard. I've seen them cause way more troubles than they're worth on big blocks that don't require a lot of timing.

Oh and by the way, most everyone I know spins the motor before hitting the ignition.

Same here. Spin it, then light it off. No biggie.

Curt wrote:I'd disconnect the start retard. I've seen them cause way more troubles than they're worth on big blocks that don't require a lot of timing.

Oh and by the way, most everyone I know spins the motor before hitting the ignition.

Most I deal with are started this way.

Rotor phase


I dont have to get mine spinnin then hit the ign, no kickbacks ever......

richter69 wrote:Rotor phase


I dont have to get mine spinnin then hit the ign, no kickbacks ever......

Not everyone has to. But if he's running a locked dizzy and a retarder, then he's probably firing on the wrong cylinder.

Just saying that there is nothing wrong with spinning then igniting. Mechanical pumps and injection are much happier that way. I have no idea what fuel system he's running.

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