belt alignment problems

ive just built a new motor for our alcohol dragster, bae cast block, bae -5 fatheads, bae manifold, new psi d, with a new rcd idler bracket assembly, new pulleys, new belt etc, when i went to crank the engine for oil pressure the belt moved straight to the back of the bottom pulley and tried to tear of the crank trigger bracket, i have tried shimming the idler pulley different directions and even tried to shim the back of the blower up just to see if any of these directions made any difference but nothing changed at all still runs to the back, tried different idler pulleys, checked everything with a straight edge appears to all be square, tried another belt , just cant figure it out, the block hasnt ecer had anything more than a line hone, the manifold doesnt look like it has been machined from new,
any help would be much appreciated
aarom

 

1st. if you shim the blower in the back it will make the belt go to the back of the pully more, think of a belt sander the more pressur you put on one side the belt goes that way.
2. try putting a big sqare from the top of the manifold to the bottom pully and see if it's true, turn the motor over too and see if the pully is running true.
hope this helps, let me know one way or the other.

 

first you need to use a surface plate sander on your manifold. get it square and remember you need to pull the manifold down the same every time or it will chande....1st step is to bolt it down just like you are going to put it on to go make a run...2nd tape it all off...3rd use your surface plate and sand it till it is all flat...you will be shocked how warped it is...4th shop vac it then untape it and put the blower on and gooooo. good luck Dave Lowe

 

Unless you think that you are a human bridgeport, this is a bad idea,if the manifold is not square to the crank shaft you can sand till you are blue in the face, after you determine that the manifold is square, then if you want to sand any imperfections off that fine, but to do it right the motor needs to go in to a milling machine to make it square. when Timmy Richards had his shop in Dunmore Pa. I watched him do this many times. he would put the block heads and manifold together and mill the manifold flat with the crank center line. and trust me you don't get anymore anal than Tim. he's the machinist, machinist. Merry Christmas & Happy New Year.