Sorry, I posted this in the wrong section earlier...

I just replaced the fast idle cam on my Holley 4180 which is in my 1983 F250, 460CID. The original is no longer available from Holley, and they directed me to Daytona Carbs. They sent me a part number H17-55 seen below. My question is how do I adjust this thing? I've been trying to figure out how to have it so the fast idle adjusting screw is sitting on the high point of the cam, but the screw does not contact the steps of the cam. Rather, it rests on a groove which is located on the other side of the cam(not visible in this picture). Also, what is the allen screw used for? I had some thoughts, but I can't get everything to sync up. What the??? I hope someone can help me with this. I appreciate any and all help.

 

Did you compare the new part with the old to see if it is a match? The allen screw is used to set the amount of choke butterfly opening. The fast idle is set with a 5/16 wrench. Wished I could be of more help.

 

Unfortunately, the front half of the old one was broken off and gone.