i installed comp cams thumper 12-601-4 duration 287/305 lift489/476 in my 400 small block. when i tried to fire it up it was making a sort of knocking/ticking sound coming from the passenger side. i backed my rockers completely off thinking it could be a valve but the noise was still there. motor never actually fired just cranked over. can anybody help me out on this?

 

Did the engine turn over completely, 360° by hand/wrench after you installed the cam? The reason I ask is because you can run into clearence problems between the cam, crank and rods/rod bolts on SBC400 and 383's made by using a 400 (3.75") stroke crank. A lot of times you have to run a small base circle cam so you have enough clearence between everything. Hopefully this isn't the case for you. Just thought I'd mention it though.

 

well it turned over fine when i was tightening the rockers for the first time and then the noise cam when i cranked it over. i had a friend tell me about the rod bolt not clearing is a possibility. if this is true is there any way to fix it and would the cam already be trashed?

 

You can grind down the bolt. I think you need .060" clearance between everything. If the rod bolt did hit the cam you probably left a mark in it or bent it. If that's the case, you'll need a new cam. You should really check all the rods for the right clearance.

 

Factory 400 rods? If so there will not be any clearance problems.

How did you adjust the cam? Hydraulic or Solid?

NEVER, NEVER, NEVER.........NEVER grind on a rod bolt!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

That's a pretty normal, completely accepted practice in building 383's.
Albeit less so today than in years past, but it's quite normal.