Question : valve train noise/want to add shims

[chippy]

I have a Pontiac grand prix 2002 with 3100 engine. I have a lot of valve train noise after having the heads & block redone. the machine shop said they took .08 off the heads & .09 off block. this also may not be the first time the heads have been done because I bought the car with high miles. I was told the max gm recommends resurfacing is .10 . the noise might be because pushrods may be bottoming out.the machine shop gave me some rocker arm pedestal shims to install .20 each. does anyone have any experience installing these & how do you tell how many to use under each palatal .

[SappySE107]

1 per pedestal. I have seen them but never used them. If you were bottoming out, the valves would be hanging open and it would not run very well if at all.

[Superdave]

I really doubt they are bottoming out, easy way to check is to pull the front valve cover, pull the fuel pump fuse and turn the engine over.. Watch the springs for full coil bind.


most likely the rocker bearings are worn, when they cleaned all the parts they knocked the buildup out of them so now they probably have some play. Check for that and also make sure the rockers are torqued to spec.

[chippy]

all parts are new lifters,pushrods&rockerarms

[kitabel]

the machine shop gave me some rocker arm pedestal shims to install .20 each

Did you mean .2, or .020"?

Material removed from the head or block lowers the rocker assembly and valve simultaneously, and raising only the rockers simply transfers the error to the valve stem height. With .170" (total mill) shims installed the rocker now point "downhill".

[SappySE107]

I am sure he meant .010 and .020, as the shop says 10 and 20 referring to thousandths. You can't take .1 off the head or deck without problems.

[chippy]

I meant to say .020

[3400-95-Modified]

Sure its not piston interference with the head? or Knock from the increased CR?

.09 off the block is quite a bit

[923.4v6]

.090 is alot, over 1/16 of an inch. I say he meant .009 and .008.
If he's right about them taking .090 and .080 which is .170 which also is almost 3/16" could that bottom the lifters out?

[SappySE107]

Add another 0. You can't take .08 or .09 off either.

[923.4v6]

Thats kinda what I figured.

[geoffinbc]

Thats nothing for machining. All he did was a small cleanup. Compression increase will be minimal and there wont be any interference. Also the lifters will be able to easily compensate for the machining. Did you put the engine back together or did the machine shop? Are you sure this noise is not piston slap or something?

[chippy]

sorry all the numbers I stated were thousandths of a inch. I have installed the .020thousandths shims I under each rocker pedestal. my valve train noise is still there. local repair shop said I should be able to remove valve cover and remove one pushrod at a time and run engine to isolate noise. has any one done this before.

[chippy]

I did the assembly except for cam bearings and installing pistons on rods . I had local mechanic listen to it and he said in his opinion it was on the top end possibly only one or two cylinders making the noise.when assembling engine followed all updated torque specs and torque angles.

[3400-95-Modified]

I am willing to bet money on the fact that its piston slap you are hearing... so many people confuse that for valve train noise. I however have some noise in mine, but thats what comes with a high lift cam and stock lifter internals BOOOO I need LT1 lifter springs!