rod knock at certain rpm

[joe sobo]

ok, i have read through other posts with this similar issue.
car is a 97 awd manual, with 16g, dsmlink v3 lite, 650 injectors, and all supporting mods.

bought the car with a spun balance shaft bearing. car only has 74000 on it. the engine looks like new. i pulled it apart and removed all balance shafts, crank cut due to bearing throwing metal through the engine. put .10 main and rods
new arps studs with all new w.p timing, so forth. also a metal h.g

put engine back in, start it up and great oil pressure, runs smooth as a new car again. take the car for a spin and i can hear what appears to be a knock at 3000 rpm to like 3300 rpm. car boost great, idles great, no noise before it and nothing after it.

now i have read on here that it coulb be a balancer making the noise i hear.

just pulled the pan, checked every bearing for damage. all in perfect shape. this engine was built correctly, and all spec were great


1) not the bearings

i guess i should swap out the balancer first before pulling engine?

just looking for someinsight before i continue

 

[doubleclutch99]

Did you have the rods resized? also what kind of bearing clearances did you get with plastigage ? are the pistons and wrist pins new as well?

 

[gixrman]

If it was rod knock when you pulled the pan there would have been shavings in the pan. rod knock sounds like a desiel engine. Sure its not lifter tic?

 

[hotrodssnova]

+1 on the rod resize. I learned that the hard way. Started off as a mid rpm knock and then a week later, the bearings spun on the rod at idle in my drive way.

Sent from my PC36100 using Tapatalk

 

[joe sobo]

why would i get the rods resized? as it did not spin any rod or main bearing to begin with. the bearings wer fine when i took them out, but had some shavings imbedded in them, so i have everything redone.
pistons are not replaced. still the originals with 70k on it

 

[bryanwheat]

If the clearences are where they are supposed to be, the bearings look good and you have good oil pressure than look elsewhere. What was your piston to cyl clearence? Also i agree if you didn't spin a bearing there is no reason to have the rods resized, UNLESS you installed arp studs in them.

 

[joe sobo]

no studs on the rods.

it is a distintive knock sound in between only a certain rpm range.

 

[g4ebguy90]

The bolts on the 7 bolt con rods, are torque to yeild, and so after they go through a couple of heat cycles, they should NOT be reused when you tear down and rebuild. It's like using head bolts again instead of buying new ones. This is mainly a 7 bolt issue, as alot of the 7 bolt's, bolts are TTY.

As for the rod itself, it should not have needed to be grinded or anything, just reconditioned for a smooth bearing surface. Also, from what I have heard is that the bore takes on a football shape from wear and stress, and reconditioning the rod removes the football shape.