Originally Posted by hotboy454
Break-in went smoothly. I used Joe Hubbard break-in oil no problem. The carb just ran a little rich even with the eldelbrock carb switched to a sumitt brand still the same. The carb was running rich after break-in. I just started to drive it under load since removing the motor del my project car to my truck. Three days under load is when the backfire through the carb happened. Started back up then the sputtering started. Looked at my plugs all of them are black and these are new plugs.
Could be nothing more than the engine needs some run time to finish breaking in and a new set of plugs will likely clear up the miss- although the root cause of the carb being too rich obviously still has to be dealt with. Did I understand correctly that both carbs ran rich, or was the engine running rough w/both but not necessarily too rich?
But, if you're getting an eye watering
exhaust smell, that's unburned fuel from not enough initial timing, not a rich a/f mixture. So if that's the case, the odor will go away when the base timing is high enough. Now, that's not to say adding timing will suddenly make the carb spot-on. You still may need to fine tune it. And the idle mixture will need to be checked/reset after changing the timing, too. Set it to fastest clean idle or the most vacuum at idle if you have a gauge.