Guys, I'm in a pinch. I just installed a Camden roots style blower on my 77 460 motor and it doesn't work because it rotates the wrong way. It came off a 73 460 out of a Lincoln or Tbird. Is there different rotating 460's?

RubberDuck

 

Which way to the rotors turn?

I will presume you are familiar with roots style blower operation, but just in case - For a top inlet style (like you would usually use with a carb) the lobes should be rotating away from each other at the top. If you were looking at the blower from the front with the cover removed, the rotor on the left would be rotating counter clockwise and the rotor on the right would be rotating clockwise.

Maybe this image created with my decidedly limited drawing skills will help. The straight lines show the direction the air will be traveling around the rotors...

carb -> lll
blower -> /OO\

Brad

 

I'm pretty sure that the crankshaft is always clockwise

Sam

 

Brad,
Are you sure? If that's the case, it would be rotating correctly. This is my first blower and I always assumed that they would rotate tward each other at the top to discharge the compressed air in the center of the intake. The truck would fire just for a second and die. We pulled the plugs and they were dry. When we pulled the blower the intake was dry. We figured it was firing on fumes. I was assuming that the blower was sucking air from the motor instead of feeding it. But now that I think about it, how would it be compressing air in between the rotors. It would compress the air against the housing in the cavity that the rotors mesh in the middle? Is that right? If so, I think I have a questionable carb. We smelled fuel like crazy, but the race fuel I run is very pungent. I'll try again with a different carb. Thanks for the help.

RubberDuck

 

Most newbies to superchargers presume the same thing. It's a common thing, so don't kick yourself over it.

The rotor lobes rotate away from each other at the top. The rotors trap air in the voids between the lobes as they seal against the blower housing. The air travels around the outside of the lobe and is exhausted under the blower. As the lobes mesh in the center they create a (relatively) air tight seal that maintains pressure in the intake manifold.

As you suspect, it sounds like you have a fuel delivery problem. Blowers can be real picky about carb tuning. Be sure to err on the rich side. A lean out with a blower usually results in a trip to the machine shop.

Unhook all the fuel lines to the carb and turn the engine over until you have steady fuel delivery. Hook up the lines and turn the engine over several more times to get plenty of fuel in the float bowls before trying to fire everything.

Also, you will probably get a first-hand lesson in how a blower will, quite literally, blow out your spark. A rock solid iginition system is a must with a blower, and you will probably want to gap your plugs down (smaller gap) a couple of thousands from the recommended gap to keep the spark nice and strong.

Brad

 

Brad,
Thanks for your help. I spent all night putting it back together with another carb, and primed it this time. It fired right off, after a few timing adjustments it ran just fine. Thanks again for your time, you have no idea how happy I am to finally have a blown big block.

RubberDuck