ragtop70

New build 350 new pistons added and comp cams roller tip rockers am I chasing a valve train noise or piston slap.



http://s20.photobucket.com/albums/b2...tlassagain.mp4

nofiveo

hard to say from teh video, but pull the covers and see if you got a mis-adjusted rocker (assuming adjustable valve train) was it rebuilt with new pistons or just freshened?

L69

sounds to me like you roller tips rockers are a tad out of adjustment. I had to adjust mine twice in my new 400 to compensate for cam breakin and wear. Readjust all your lifters (roller rockers) and I bet the sound goes away.

TripDeuces

Piston slap would make it sound like a diesel engine. That being said I don't hear that in the video. Get a length or rubber hose and use it as a stethoscope and run it along the areas you suspect the noise from. You'll find it.

oldcutlass

Or you can just pop the valve covers off readjust the valves and see if the noise goes away? How are you adjusting them?

ragtop70

OK so I have adjusted the valves a few time here is how I have done it. First I bring it to TDC on the compression stroke and adjust the intake and exhaust valves then rotate the engine 90 then move to the next cylinder in the firing order.


To adjust I tighten the rocker to 0 lash (spinning the push rod till it stops) from 0 lash I have gone ½ turn and also I have tried ¾ of a turn. Also I have attached a photo of my valve tips I did the sharpie thing and turned over the engine a few times to see check the push rod length.

valvetips8242012.jpg

ragtop70

I'll give that a try later this week and I'll post my results. My distributor is bolted down what else should i check on it.

Thanks

joesw31

Sometimes, the distributor will push down the oil drive shaft down on the oil pump gears and cause excessive noise. It depends if you changed the oil pump shaft and/ or the distributor has been changed, or shimmed.

ragtop70

Interesting I'll take a look at it. The oil pump and shaft and distributor were reused.

Thanks

SBORule

Sounds like to me, like you may have too much preload on the lifters.

Some hydraulic lifters have a tendency to bleed down pretty quick, so when you put the rockers back on, you might want to just tighten them down just enough so there is zero lash between roller and valve stem and you can turn/spin the pushrods without much effort.

Start the engine and let it run for awhile and then recheck valve lash. If you hear ticking, then you know you have to add a 1/4 turn on the locknut.

ragtop70

Question how would too much preload cause it to make noise?

gregvm

You say NEW pistons? Forged or cast? Was it rebored? What's your piston/cyl wall clearance? That sounds like piston slap to me. My 455 with K/B's sounds like a diesel when cold.....goes away soon as it warms up. Price you pay for forged slugs. Better to be too loose on the wall clearance than too tight. Adjust the valves....
We'll go from there....

Greg

ragtop70

Ok I redid my valves 1 complete turn from 0 lash I still have the same noise and now I can hear some lifter ticking so I am going to back them off ½ .



I have a mechanics stethoscope and the sound is the clearest at each header tube the rockers are not hitting the valve covers or the stud. Now for a dumb question what if I degreed the cam wrong I had to install it 4 degrees retarded to get the correct center line if I did this wrong could the pistons and valves be touching the piston to deck height is .006 and my head gasket is .045.



If it was piston slap would it not quite down after it warmed up. The pistons are Diamond forged pistons the engine was bored 30 over a few years ago but 23cc pistons were used so I had new pistons pressed on to my rods and was told to do a light hone myself with a ball hone. Piston wall clearance was not checked I was told not to worry about I guess I am now paying the price.

oldcutlass

Remove the valve covers, start motor, back the valve adjustment off until they start to clatter, tighten until they are quiet, and give it 3/4 turn tighter from there, lock them down.

oldcutlass

Some roller rockers are just noisey to start with! All the adjusting in the world will not quiet them down.

captjim

BAD advice, IMO. Not at all accurate. The procedure that Joesw31 gave is the correct way to set lifter preload.

captjim

That is ridiculous,. roller rockers are NOT noisy. Some cams with very steep ramps are, but not the rockers.

oldcutlass

With all due respect, there are many ways to adjust valves! You can do the method with the engine off and rotate the the crank as described above, or the old fashioned way as I described. This is the messy way of doing a valve adjustment on hyd. lifters and has been done this way since the dawn of time. They are hydraulics, how accurate does it have to be. The problem doing it with the engine off is the lifter sometimes collapses and there is too much preload, crank position not correct, etc... The old fashioned way, they are all pumped up and it's always right.

Yes I agree the with the cam profile being the culprit to the roller rocker noise, however there are some roller rockers that just plain suck.

gregvm

Did you install those stupid heat riser block off plugs in your heads? They can cause all sorts of weird sounds, especially around the exhaust like you described.

ANY machinst that told me "not to worry" about the piston/wall clearance, I would grab my parts/block and RUN as fast as I could away. It's VERY important: Too tight: scuff the pistons, ruining them and possibly the cyl. walls, and cause overheating. Too loose:Not as bad, but will cause excessive noise and possible ring breakage(rings flexing too much)
Forged pistons expand more than casts, so you need a looser clearance when cold to compensate for them expanding hot, hence the noise when cold.
You would know by now if the valves were hitting the pistons....no/low compression. Didn't you check your piston/valve clearance with clay prior to running the engine?
Could be a wiped bearing as well. What's your oil pressure like? Did it suddenly drop? Remove your oil filter, cut it open, and examine the cardboard element. If it looks like "glitter" that's bearing damage.
Hopefully it's just as simple as the valvetrain
Greg

captjim

I worked at an engine building shop for several years. We did everything from 8 second race cars to stock resto builds. We always set the preload while assembling the engine and never had an issue. It is especially easy with the intake off where you can actually watch the plunger move. I too have done it with the engine running on SBCs and it works but is soooooo messy.

oldcutlass

So back to your original statement pertaining to what I told the OP to do earlier that it was not the proper method and not accurate to do it this way. What makes an Olds with adjustable rockers any different than a Chebby?

MDchanic

If I recall, adjusting while running is actually the CSM-recommended way of adjusting valve lash on the SBC. They even list little tabs you can clip on the rockers to keep the oil out of your face. The Olds has an advantage in that department, as the oil flow to the top end isn't nearly so much, so there's much less of a mess.

- Eric

captjim

Not going to derail this, you have your opinion, I have mine. If you think loosening a lifter and listening for it to start "clacking" while the engine is running and hot oil if flying all over the place is better than the method Joe suggested (which is the way I do it) then we will just have to disagree.

oldcutlass

The other advantage, or sometimes disadvantage is the lack of adjustment on the stock Olds valve train.

ragtop70

Sorry for the long post..

I did not install the heat riser plugs but the head did have the heat risers filled and the intake had the risers welded closed. The oil pressure at start up is 50 drops to 20 at 1000rpm when temp is at 180.
I have done the valves a few times and have gone as far as 1 ¼ turns anything more than ¾ and it starts to make a sound like lifter tap besides the other noise. If it is the pistons would they not quite down after warming up?
Here is some more back round this is the second attempt.
First time replaced pistons, rings and honed, installed comp cams roller tip rockers and welded up heat crossovers on intake (did not do anything to heads or replace cam and lifters)
After starting for the first time I had the noise you here in the video after many valve adjustments I discovered that the rockers were hitting the studs. Then had the heads milled to make up for the guide plates and had the heat risers filled since the heads had to be disassembles anyway. Also decided to replace the cam and lifters at this time while I had the engine out looked at the main and rod bearings they all looked good but I did not check the clearances (I know I know) put it all back together same noise. Also it did not show any sign of the valves making contact with the pistons I did figure if that was the issue something would have broke by now.


At this point I am willing to try anything so I may try the running valve adjustment.

captjim

Doesn't sound like pistons to me. Are you positive that the rockers are not hitting the valve cover someplace?

ihengineer76

I'll agree, this method is a PIA. We had to do it this way on my dad's GTO since it needs to be set to 0 lash hot. I cut a pair of valve covers with just enough opening to get to the adjustment nut. I still had oil flying, but not as much.

To the OP, what cam lift are you running. The only other thing I could think of causing noise in the top end could be spring bind if the springs/dampers weren't checked. Its a long shot, but something maybe to check.

captjim

That sounds to me like solid lifters, whole different deal. But, I have set plenty of them the exact same way as previously mentioned, you just let the engine warm up first.

ihengineer76

Not solid lifters, just the way Ram Air 4 engines are I guess. We set it up with 3/4 turn preload like most engines, and could not get it to run right at all. We had to call a friend of ours that has raced the Ponchos for a long time and he told us how to set it up. The girl sure does tick a lot until its warmed up!

ragtop70

I have stock valve covers with the baffles removed and 2 cork gaskets under each valve cover. I colored under the valve covers with a sharpie and I do not see any marks.

I am running valvoline vr racing oil 10w 30 none Synthetic.