knocking noise on 408 stroker

[leanburn]

we just got done putting my 408 together and i have a knocking noise at all rpms. it seems to be with cam speed not crank speed and we cannot narrow it down. it seems to be coming from both sides of the engine and we tried adjusting the lifters to see if the noise would change but no luck. is there anything i can try before pulling the motor out and tearing it down. here's the build: 360 block bore 40 over, scat rotating assembly with a lunati 405 cam and hydraulic lifters, eddy heads with crane 1.5 rockers. the shortblock is all brand new stuff but the heads were off my 340. other than the knock this thing runs spot on but it was knocking as soon as we fired it up.
 any help would be appreiciated.

[Moparal]

Did you make sure the fuel pump ecentric and cam bolt was tight?  Oil pickup square to the pan and not hitting the crank throw?  balancer bolt tight?  just a few of the top of my head

[leanburn]

balancer bolt is definately tight, oil pickup i'm sure is fine, we turned the engine over by hand quite a bit when we installed the windage tray.
 i will check that ecentric before pulling the motor.

[jimynick]

Did you check for decent crank throw/connecting rod clearance at the bottom of the cylinders when assembling it? Cam speed is half crank speed, so maybe a lifter or rocker arm. Do the rocker arms contact the spring retainers?
Just a few ideas. 

[leanburn]

this rotating assembly i bought is awsome for clearance, we even used a stock windage tray just by shimming it up a hair.  i don't see any problem with the rockers hitting the retainers..  keep em coming, anything at all guys.

[Jim]

this rotating assembly i bought is awsome for clearance, we even used a stock windage tray just by shimming it up a hair.

I couldn't even come close to getting a stock windage tray to clear the SCAT I-beam rods in my 410/360. Of course, I was using a modified 340 pan and that could be the difference.

Rockers hitting the valve cover baffles?

[leanburn]

still makes the noise with covers off. it sounds '' deeper'' than rockers. something with the lifters or cam i think.

[mojavered]

Possible exhaust leak or fp push rod?

[leanburn]

it's definately not an exhaust leak, it a knock more than a tick for sure. what do you mean by a fp push rod?

[mojavered]

I know you said it sounds even on both sides, but just thought maybe fuel pump push rod?

[ireland383]

I know you said it sounds even on both sides, but just thought maybe fuel pump push rod?

Fuel pump pushrods are for big blocks.  Possible rod knock.

[femtnmax]

Put a timing light on the engine while its idling....does the sound match the flash of the light?   The light is flashing at 1/2 crank speed (spark ignition), and is flashing at same rate as cam rotation.
With engine idling, pull spark plug wires off one at a time, does knock go away on a certain cylinder?   No spark is taking the spark ignition load off the rod journal of course.
With a long screwdriver, put the plastic handle to your ear, and the metal blade end against the engine block, valve cover, water pump, etc, can you isolate the sound to a particular area?  Watch out, don't let the blade get caught by the rotating fan blades!!  It has happened, not to me thank goodness.
Just a few ideas.

[mojavered]

Fuel pump pushrods are for big blocks.  Possible rod knock.

Thanks, did not know that!

[The Cuda Guy]

I would have guessed header gasket leak, but you said it sounded deeper?  Did you check the header gaskets?  If not what is it going to hurt at this point? 

Don

[leanburn]

pulled the motor out, took the heads off and walla, the guy that assembled the engine was very embarrased when we found that two pistons were installed 180 degrees out and the valve was touching the pistons. motor is back together and in the car. went for the first rip and blew the tranny yoke....  and so it begins!!!!!!!!!!

 thanks for the help guys, this one really suprised us, this guy is usually very meticulous but i can see how easy it would be to make that mistake.