Intermittent engine noise

[Trueweltall]

to start with some info: brand new motor built. eagle ross combo arp everything and fed mogul bearings all parts brand new. motor built and machined professionally at a known good shop.

now the problem. there is a noise that appears to be comming from the bottom end of the engine. sounds like a knock or a repetitive tapping noise. although this noise is not consistent. it comes and goes at idle and on throttle.

so i drained he oil and pulled the pan. good news is that there is no metal shavings in the oil or anything abnormal in the oil. after pulling the pan i check the torque specs on the main caps and they all checked out to the right spec (60ft/lbs on arp's).

at this point i am lost. i then rotated the crank while under the engine to check for any problems or interference with anything, still nothing. and then i noticed that i could move all four rods side to side on the crank about a 1/32 of an inch (estimate i didnt measure it).

this doesnt seem right? i havent dont anything from this point other then search the forums. can someone please help me diagnosis this issue? suggestions and/or similar problems welcome. thanks

 

[staticbrainwash]

if you got it built at a good shop there should be a warranty. i'd take it in and explain the noise you are hearing. they should be able to figure it out.

as for the space on the crank for the rods, i have no idea. Realistically they NEED to move some otherwise they wouldn't spin on the crank. I'd measure it and let us know what you get, other than that, take it back to your shop and make them fix it.

Did you break the motor in properly?

 

[jott5555]

what it sounds like if im understanding correctly.. they may have done a grind on your crackshaft (lots of machine shop's do if there are any imperfecton's on the crack) and you didnt your bearings oversized to compensate.. basicallly your rod with bearing are probally .010 to large for your crankshaft.. depending on how long this went on.. you could have tourched your bearing's or crank due to imporoper wear..

regardless you need to look on your paperwork from the machine shop they would have specified if they ground the crank.. or on second thought.. you may have the wrong series of rod.. possiably

 

[GVR4592]

I may have missed it, but I didn't see you mention anything about balance shafts. Chances are you had them removed when you did the build, but if not the bearings can get screwed up pretty easily and they would make a sound similar to what you are describing.

 

[Trueweltall]

what it sounds like if im understanding correctly.. they may have done a grind on your crackshaft (lots of machine shop's do if there are any imperfecton's on the crack) and you didnt your bearings oversized to compensate.. basicallly your rod with bearing are probally .010 to large for your crankshaft.. depending on how long this went on.. you could have tourched your bearing's or crank due to imporoper wear..

regardless you need to look on your paperwork from the machine shop they would have specified if they ground the crank.. or on second thought.. you may have the wrong series of rod.. possiably

well guys. the bs was eliminated. and the bearings were removed i watched it happen so i can remember that specifically. but i looked into it and they did not grind the crank. just polished it. i had two cranks that i brought to use whichever was best, since i had already bought standard size bearings. but maybe he messed up on that....i hope not. the engine running has about less then 200 miles on it. odd thing is this didnt start right away. it was near the end of those 200 miles it has been driven. and can u explain about the wrong series of rod?? from eagle?? god i hope not. thanks guys

 

[jott5555]

If i remember correctly and it has been a while.. the road diam is diffrent on 1g and 2g crank's maybe eagle sent you 2g rod's and your useing a 1g crank kinda thing... i know its a stretch.. anyway ide verify they didnt jack up your crank shaft.. pull a rod off and use a caliper and measure it..