Motor Backfires Thru Exhaust When Trying To Start

[patrickt]

OK, since you now know where on your balancer TDC is located, let's just do a "double check" to be absolutely sure. Pull the spark plug out of the #1 cylinder hole and put your stick back in its place. Place a little piece of duct tape on the side of your distributor directly under the location of the #1 plug wire. Now remove the distributor cap, leave the rotor in place, and rotate the engine via the crank bolt. You should see the stick coming up out of the #1 cylinder as the piston is pushing it up. At the same time, you should also see the balancer begin to get closer to the TDC location. Also at the same time you should see the rotor begin to get closer to the duct tape that marks the #1 plug wire. When the stick is at it's highest point out of the hole, and your balancer says you're at TDC, then the rotor should be pretty darn close to the duct tape. It doesn't have to be perfect, we're just checking to make sure it's not way, way way off. If the rotor is pointing to the other side of the distributor, away from the duct tape, then you've found your problem.

[Jim Coleman]

Originally Posted by patrickt

OK, since you now know where on your balancer TDC is located, let's just do a "double check" to be absolutely sure. Pull the spark plug out of the #1 cylinder hole and put your stick back in its place. Place a little piece of duct tape on the side of your distributor directly under the location of the #1 plug wire. Now remove the distributor cap, leave the rotor in place, and rotate the engine via the crank bolt. You should see the stick coming up out of the #1 cylinder as the piston is pushing it up. At the same time, you should also see the balancer begin to get closer to the TDC location. Also at the same time you should see the rotor begin to get closer to the duct tape that marks the #1 plug wire. When the stick is at it's highest point out of the hole, and your balancer says you're at TDC, then the rotor should be pretty darn close to the duct tape. It doesn't have to be perfect, we're just checking to make sure it's not way, way way off. If the rotor is pointing to the other side of the distributor, away from the duct tape, then you've found your problem.

Patrickt:


It appears that the balancer is at 2 degrees after tdc (The line marked 5-8 on the balancer if the stick is all the way up), and the rotor is pointing at cylinder#3 instead of #1.

Do I need to start over?

Thanks,

Jim

[patrickt]

Originally Posted by Jim Coleman

Do I need to start over?

Thanks,

Jim

I'm not sure. If you have marked TDC properly on your balancer, then it should be easy to get the engine to start and run without having to pull the distributor out again. Even if it's in wrong, we'll just rotate the wires around to match where they "should be." Let's assume you followed my instructions correctly and have marked TDC accurately.

First, follow these instructions from blykins:

Pull the driver's side valve cover off. Roll the engine over by hand and watch the rocker arms on #1. Roll the engine over until you see the exhaust valve on #1 open then close. At this time the intake valve should be opening as well. Keep rolling the engine over until the intake valve opens, then starts to close. At this time, keep rolling the engine over and be watching the timing pointer and the balancer. When you get to 30° BTDC, stop.

When you do this, where is your rotor pointing?

[Gaz64]

Originally Posted by Jim Coleman

Patrickt:


It appears that the balancer is at 2 degrees after tdc (The line marked 5-8 on the balancer if the stick is all the way up), and the rotor is pointing at cylinder#3 instead of #1.

Do I need to start over?

Thanks,

Jim

Jim,

The 5-8 mark would be 90 degrees after the 1-6 mark.

The 1-6 mark is the one that should line up when finding TDC on cylinder 1, (or 6).

So the balancer outer ring has shifted, or some other abnormality.

And if you are on TDC 1, then the rotor pointing at 3, is why it won't start.

I am more concerned at why the balancer does not line up.

Gary