Looking for some feedback on a back firing issue I am having. It started after my last rebuild of the motor (carb is the same and not rebuilt). Have had a hard time getting it to idle properly (or close to properly for a 12.5:1 compression with a big stick). Before the overhaul I always idled around 1700 with a rough idle so the idle quality is nothing new. What is new is that I am backfiring when I start it up. This evening I was trying to start it to work on adjusting the idle mixture and the damn thing kept blowing a flame and catching the carb on fire:eek:. The carb is a HP4150 , 950 cfm. Thought it was the timing the other day and bumped it up a bit to about 37 degrees (was 35 to run pump gas). Almost seems to have made the backfiring worse.
My idle mixture screws are turned way out to 2 1/2 turns trying to get it to idle. This is what I was going to try adjusting today. I set them at 1.5 turns to start and that was when it backfired. After a couple of tries at 1.5 turns i turned them back to 2.5 and it still backfired :( I'm sure my new power valves are toast again....
I am now wondering if the timing pointer is set correctly. When I had the engine apart I had the shop install a new timing cover and one of those billet pointers that bolt on. I assume they set it up properly at the shop but maybe.... or it might have lossened up.
Any other thoughts to check?
My idle mixture screws are turned way out to 2 1/2 turns trying to get it to idle. This is what I was going to try adjusting today. I set them at 1.5 turns to start and that was when it backfired. After a couple of tries at 1.5 turns i turned them back to 2.5 and it still backfired :( I'm sure my new power valves are toast again....
I am now wondering if the timing pointer is set correctly. When I had the engine apart I had the shop install a new timing cover and one of those billet pointers that bolt on. I assume they set it up properly at the shop but maybe.... or it might have lossened up.
Any other thoughts to check?
