Backfire under loads

[kazoocruiser]

Originally Posted by Pontiac1976

I the balancer is the 305 it should be hollowed on the back side, since you dist. was mechanical weight wore. And timing chain and cover might have been wrong or changed, might have wrong balancer or the rubber seal ring slipped. this would make it hard to get TDC lined up right.

I was thinking about this some as well. If he has a two-piece balancer, maybe it is starting to delaminate. If the engine is rotated around to #1 TDC, the timing marks ought be be lined up. If they are not showing TDC, That might be contributing to some of this hard to fix ness.

I had a Toyota that had a pulley come apart at highway speeds, but before it did, I ran out of room on the distributor slot trying to get the ignition timing correct. It kept showing late. I think I even tried to reset the distributor in the block.

Geezer#99's link gives a way to check if the balancer is bad.

Checking the outer damper ring for movement
Damper line.jpgDraw a sharpie line as shown in the image below. When the timing light is pointed at the TDC line, the sharpie line will also be seen. By revving the engine and running it at different speeds, if the outer ring is loose, the line on the outer ring will be seen to move independently of the line on the inner hub. Over time the line may be seen to have separated as the outer ring has moved independently of the inner hub.