Rod knock?

Old 06-30-2009, 02:59 PM
  #1  
gcp
Junior Member
SHOW GUEST
Thread Starter
 
Join Date: Mar 2008
Location: Central Minnesota
Posts: 7
Default Rod knock?

:evil: Maybe this post should be in the angry venting category...???

So I was helping troubleshoot a SBC problem over the phone Sunday evening. Sure sounded like a rod knocking - but it was over the phone... I wanted them to check the valves but they were going to pull the engine instead.

Today the knock was quieter and then went away after revving the engine a little bit???

Now I hear it's running fine and that they did check the valves - one lifter was stuck up??? I call BS! The engine would be backfiring one way or another if the valve was open. How can a lifter get stuck upward after doing a carburetor swap?

Anyone hear of knocking "going away" the next day?
gcp is offline  
Old 06-30-2009, 03:21 PM
  #2  
ARUSSELL
Senior Member
MASTER BUILDER
 
Join Date: Mar 2008
Posts: 193
Default

I come across this all the time with people not used to forged pistons, and complain when the engine is cold, but after is is warmed up, noise goes away
ARUSSELL is offline  
Old 06-30-2009, 04:00 PM
  #3  
MEMRACING62
Senior Member
RACING JUNKIE
 
Join Date: Sep 2007
Location: orland pk il
Posts: 2,429
Default

does it have mechanical fuel pump?? push rod could have been sticking in bore a little knocking the cam
MEMRACING62 is offline  
Old 06-30-2009, 04:03 PM
  #4  
Scooterz
Senior Member
RACING JUNKIE
 
Join Date: Mar 2006
Location: EUGENE,OR.
Posts: 3,408
Default

Is it a solid lifter motor? I hear some lifter noise/knocking occasionally when they are cold or loading up some... they can be noisey...

Tough to tell on the phone too...
Scooterz is offline  
Old 06-30-2009, 04:16 PM
  #5  
wmeabates
Senior Member
MASTER BUILDER
 
Join Date: Sep 2005
Posts: 134
Default

Noise after a carb swap,something might have fell into the intake.Hope not. Bill.
wmeabates is offline  
Old 06-30-2009, 04:20 PM
  #6  
CamBirdRacing
Senior Member
DYNO OPERATOR
 
Join Date: Feb 2009
Posts: 510
Default

I changed rocker arms on my Pontiac years ago and broke a crank, haha. Ran better than ever.
CamBirdRacing is offline  
Old 06-30-2009, 05:14 PM
  #7  
gcp
Junior Member
SHOW GUEST
Thread Starter
 
Join Date: Mar 2008
Location: Central Minnesota
Posts: 7
Default

It's a stock 350, cast pistons, hydraulic lifters. It does have a mechanical fuel pump... Never heard one stick before.

Over the phone this thing was thumping pretty hard. They said the sound seemed to come from down in the center of the engine.

Who knows??? :?
gcp is offline  
Old 06-30-2009, 05:36 PM
  #8  
MEMRACING62
Senior Member
RACING JUNKIE
 
Join Date: Sep 2007
Location: orland pk il
Posts: 2,429
Default

mechanical fuel pump. i had a new pump arm stick and not return fast enough and knock against the cam and sounds like a rod knock that can come and go. push rod for pump could be binding in its bore and do the same.
MEMRACING62 is offline  
Old 07-03-2009, 07:10 AM
  #9  
sm44
Junior Member
SHOW GUEST
 
Join Date: Mar 2009
Posts: 8
Default

flexplate?
sm44 is offline  
Old 07-03-2009, 07:37 AM
  #10  
THERATTLER
Senior Member
RACING JUNKIE
 
THERATTLER's Avatar
 
Join Date: Sep 2003
Location: LICKSKILLET , MISSISSIPPI
Posts: 1,474
Default

I have heard a terrible knock in a chevy 350 in a corvette..it was carbon on top of piston , sounded just like a rod...poured trans fluid in carb with engine revved up to break it loose , knock went away , still running today..
THERATTLER is offline  

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service