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Old 09-30-2008, 03:03 PM
elkyholic elkyholic is offline
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new engine knocking

Help! I am new to this... I am trying to install a newly rebuilt sbc 350 engine into my 67 el camino. The engine came from a shop who apparently built it from "extra" parts. What I know (or so they said): 1995-2000 gm crate engine block (casting numbers verify) cleaned, checked and honed by machine shop - Gen1 with one pc rear main seal, "Hecho en Mexico" 72cc heads, no work done, came from a newly rebuilt engine cust changed mind on heads took them out before driving (numbers verify and look new), stock vette 5.7 rods, stock crankshaft from crate motor (casting numbers say is forged??), new flat top pistons (speedpro), new "big" comp cam hydraulic flat tappet don't have specs, can't get - sounds like a MONSTER when running, new push rods, new Harland Sharp 1.5 rockers (with stud girdles), and new TCI flexplate... I know more but I think this gives you what you need for this question -

We got everything hooked up, mechanic friend adjusted rockers, fired engine up, minor adjustments to get it to idle, then warmed it at idle. 50# oil pressure, 160 degress warm. Then it started a knock. A bad knock low in the engine. Cut it off, pulled engine and took back to shop we bought it from and they told us "could be cam is too big or rocker arms aren't made for this motor." It's under warranty and they agreed to make it right and are sending it to machinist but question is - wouldn't that have to be a bearing? And if so would a bearing be affected by the size of the cam or rockers? Also if it was a bearing is there a danger of block damage now? I just don't want them to get the knocking to go away then us have trouble after the warranty period. Also I read somewher on a post that a cracked sark plug might cause that sound??? When we took plugs out they were a little oily, dark, and one of them was cracked...

Any help or opinion is MUCH appreciated. Sorry for the long story I just started with what I figure you might ask.

Newbie mechanic in despair
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