I had to measure the exact diameter of the nipples on these tubes and drill out the manifold holes to just a few thousandths smaller as they wouldn't just fit into my original manifolds. Might be because of the ceramic coating on the manifold though. Also, the lines didn't just hook right up to the carb. They needed to be bent a bit to go to the right spot. Also, It helps to screw the heat tube into the carb before installing the carb so you don't cross-thread the aluminum fitting on the choke body. The heat tube's insulation sleeve is pretty difficult to slide on and is about a half inch too long giving it a kind of bunched-up look. Can't cut it shorter or the treated ends will be removed. Other than that, the kit works and looks fine (289 with a 4100 carb on a 1" original spacer).