69 c10 questions

[billy37380]

i have a new rebuilt 283 sprint motor in my 69 c10 it has less than 2800 miles on the rebuild.

when i am sitting at a stop lite you can hear it kinda backfiring is what it sounds like it is not real loud. But when I am driving down the road it runs fine and drives great except when i coming to a stop from 45mph to a lite you can hear it a little bit then. Also I noticed last nite that there is blue smoke coming from the exhaust when I was sitting at the lite but again when driving it doesnt show any smoke

[hyarbour]

Sounds like your carb might be running a little rich and causing the backfire. It can also be caused by too large an exhaust system if it happens as your letting off the throttle. For the smoke do a compression check and see if you got a cylinder going bad, if ones real bad it could also cause a backfire because of unburned fuel and oil going out the exhaust.
Good luck

[mnunn454]

Sounds to me like either the ignition timing or the cam timing is off, but it's hard to tell for sure without more details.

If it's ignition timing or firing order, that's easy enough to diagnose and correct yourself.

If it's cam timing, you'll need to talk to the engine rebuilders. It's not a hard thing to fix, but it will require dropping the oil pan, the timing cover and the valve covers and you don't want to tackle that yourself if it's under warranty.

JMO