Backfiring TO-20

History.

Just finished a full engine and carb rebuild. Doing some tune-up work today after installing a new steel gasline. Valves were set correctly. Good fuel flow. Good spark.

Choking helps a little as does a slight increase in tension on the throttle rod. However no clear solution.

I will check compression later today to see if valve issue. Any other good suggestions?

Mark

Mark

Also make sure that your initial timing is correct and that that the distributor advance system is working as it should.

Check the distibutor for shaft/bushing wear (often the cause of weak spark) by making sure the points are closed and pushing radially (from the side) on the distributor shaft. The allowable radial runout is 0.002" and the points should show no motion when you perform this check.

thanks for the reply.

I have read your comment about spark many times. The spark is as expected. This does not appear to be a weak spark issue.

I have not touched the timing since she was running last week. It would seem odd if the timing/points/distributor had a failure just by sitting. I will check anyway. Maybe I have an intermittant miss.

With the engine warm 10-15 minutes low idle the presssure is better than 100psi for all cylinders so it does not look like a valve.

Mark

I did not pull the distributor during the rebuild and she ran well after reassembly. so the timing was never messed with.

I will recheck the carb to manifold bolts maybe something is a little loose.

The new fuel line should make things better. The old fuel delivery was a mess of splices, hose and tubing. She clearly now flows like "a cow pissing on a flat rock" as is said around here.

Mark