I was worried too because mine were closed pretty far. It raised the idle rpms by 200 but I was able to lower back down with out any problems. Just make sure that you can get the min 12"hg in D. I was first showing 11 3/4"hg and the vacuum and idle was still steady. But I didn't feel comfortable with running with less than FBO suggests.
Last edited by YO7_A66; 03/11/1206:17 PM.
1970 YO7 A66 [Canadian Export] F8 Challenger 340 (Currently in shop for stroker assy.)