I just put full length headers on my 350 and it is now noticeably harder to start while cold. Before it was full choke, 3 pumps and fired right up. Now same routine and it turns over for a good 8-10 seconds before starting. I have verified that the choke door is closing when manual choke knob is pulled. :confused:

Anybody run into this before? If it matters, here is the rest of the set up: 350, mild perf. cam (.454" & 218 deg. at .5), manual choke 600 cfm carb. stock heads with 9.6:1 CR. Thanks for any ideas.

maybe crossed a couple plug wires when they were off???

IMHO, a carb should be retuned if there is a change in exhaust pressure, try and adjust your idle mixture screws and see if that makes a difference. Main jetting may have to be changed as well, but that should not affect starting. Just my .02 worth