cam trouble
#1
cam trouble
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?
#2
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.
#3
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?
#4
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.
#6
Albeit less so today than in years past, but it's quite normal.
Thread
Thread Starter
Forum
Replies
Last Post