Piston Slap - questions

[XH29N0G]

Thanks for the advice.  It will probably take me a little more than a week because it just cooled down again (nothing close to Alberta cold, but cold enough to slow me) and because I have to take a quick trip.  I will post again when I find out what sort of difference this makes.

[kokxville]

I just watched the YouTube vid you posted 

Maybe said before,but ALWAYS start by checking the oil pressure first.
If i hear that noise,i immediatly shut the engine off and check this first of all.

Are all your internal oil canals open? ( Like the main,rod and cam bearings mounted the right way? )

Are the lifters ok?

If you are sure all of the above is good,then i should start by trying different oil.

[XH29N0G]

Thanks for the feedback.  It certainly is something I think about. 

I cannot speak to the internal passages, but the engine has sounded like that since I received it and the oil pressure gauge (factory gauge) usually reads about 40 psi or higher.  It rises slightly with RPM and drops a little at idle.  The engine has a new oil pump and the dyno sheet had it 47-49 psi.  So I am hoping I am OK.  The sound is also a little different than I heard (before the rebuild) when oil was low. 

[BSB67]

Thank you Ron and Challenger340 for your thoughts.  

OK,  Here are the videos.  I am not sure they are clear enough to really show the difference.  There is a difference once the car is warm, but the sound persists.  If I slow the idle to 700 RPM it becomes more pronounced.  I assume I should set the idle higher (per discussions on the forum)

http://youtu.be/gu18c9hpwaI is of a cold start at about 1200 RPM

http://youtu.be/dY-2M7VvYA  Cold start about 900 RPM

http://youtu.be/vUBqikxDSQ0 Warm engine idle at about 900 rpm

I have a motor with Rhodes lifters in it and it sounds similar to what yours sounds like.  You might want to check if MM used any type of bleed down or variable duration lifters.

Heavier oil will also make them quieter.

[XH29N0G]

Thanks.  I think I will check the oil first and then reassess things.  All of this is appreciated.  With my old set up, I did have noisy lifters and it did seem they would quiet with heavier oil.

[StockMan]

Some manufacturers sell rod bearings that come without the notch that enables that nice spray of oil onto the cylinder walls. 
I cut these notches back in to mine, I always wondered what would happen if they weren't there. 
That oil would provides extra ring lube and could possibly provide a cushion to prevent some of that piston skirt slap.

Just another suggestion...

[XH29N0G]

So I changed the oil as suggested to Brad Penn 20W50 and there is a noticeable difference.  There is still a sound, but it is much less pronounced. 

http://youtu.be/gu18c9hpwaI is of a cold start at about 1200 RPM

http://youtu.be/dY-2M7VvYA  Cold start about 900 RPM

http://youtu.be/vUBqikxDSQ0 Warm engine idle at about 900 rpm

http://youtu.be/40pFbx4Xnro Warm engine after oil change to 20-50w at 1000 rpm

I am going to keep track of this for now, and also see whether it changes. 

[Cooter]

So do you have a detailed list of what parts are in the engine? I'm wondering just how short a piston is in a 3.900 stroker....
I guess it could be 'normal', but I'm thinkin somethin ain't right. I know I couldn't live with that, without some loud mufflers at cruise night.
The "your sh*t is knocking" comments would drive me nuts.

[cudaken]

If my motor sounded like that I be pissed! Even with the 20-50 it sounds like a diesel!

First think I would do is do a oil presser test, after all these year I would not count on the stock unit. While the dyno sheet stated around 45 PSI or so and that is with in stock range, I would think it should be a little higher? 

Long time ago, a old trick was to run the pistons backwards, when cold it had piston slap but warm it was gone.

When you changed the oil, did you cut open the filter and look for metal? Maybe the cam is going flat? I would all so pull the valve covers and look at the valve seats and see if there is anything wrong?

Now, don't go just by what I said, wait for Ron and or 340 to chime in!

First time I started my 68 Road Runner after sitting 8 years it was quieter than yours.

Good Luck, Ken 

[XH29N0G]

Thanks Cooter and Cudaken,  I'll wait for some more feedback, but your responses will push me to continue to look into it.  For what it is worth, I did not sense any blow by out the hole the PVC goes in or out the dipstick at 1000 rpm.  My understanding is that the pistons are 1.32 " high.   The engine Temp gauge was at 200 F and the oil pressure is still in the high 40 range on my gauge. 

[cdr]

have you called MM  & talked to them yet?

[cudaken]

 I missed stated, look at the valve spring seats, not the valve seats.

Cuda Ken

[XH29N0G]

CDR: Not yet.  I will.  I just wanted to do the oil test and any other tests that should be done first.  

Cudaken (and others) My thinking is that some of this might make sense to wait until after I contact MM.  Are there any tests I should do in addition to the oil change before calling them?  If it comes to it, I will need some guidance on what to look for at the valve spring seats, and also about oil pressure test. I took a look at the filter and did not see any obvious metal (looked with a jewelers magnifier). 

I will sign out shortly, but will be back on.  I appreciate the frank feedback.

[kokxville]

This sucks really bad,i would not be happy if i spend that amount of cash and it sounded like this
Take your oilfilter off,and cut it to see if there's metal in it.Double check your oil pressure.
Call MM,tell them about your problems and make that thing running fine.Cruise season is ahead 

[Cooter]

I thought MM hadda good rating?
Heard and read lots of good reviews??
I wonder if they will attempt to repair it?

[XH29N0G]

Hi Cooter,

I just sent them a note with the links to the videos and hope to call them next week about this.  They have been good to deal with so far, and I expect they will be fine to deal with on this. 

[Cooter]

Hi Cooter,

I just sent them a note with the links to the videos and hope to call them next week about this.  They have been good to deal with so far, and I expect they will be fine to deal with on this.  

Let  us know the verdict. Careful with those "notes"....

[firefighter3931]

Definately sounds better with the BP 20/50 oil 

Listening to that vid clip it sounds more valvetrain related to me 

The Comp Cams XE hydraulic grinds tend to be a bit noisier due to the agressive lobe profiles. I'd try to find out what lifters they used as well....could be an issue there 

My old 446 with a solid lifter cam sounded similar to this one at idle....


Ron

[XH29N0G]

Thank you,

What I have as the build that appears to be relevant to the discussion so far is:

std melling oil pump M63

Cam and lifters: Comp cams listed as .519/.511 236/246@50 (I think 280/296 is the advertised duration) with 112 LSA.  The rocker arms should be the stamped steel rockers.  The lifters are listed as Comp cams hydraulic lifters (822-16).  The timing set is from comp cams (2104). Rockers should be stamped steel rockers.  They listed the spring pressure as 120 on seat.

Heads are Edelbrock RPM that I had, but they added with 10 degree retainers and locks from comp cams (741-16 and 611-16) and did a valve job.  There is a number on the build sheet in the spot where they would put the valve lash (which I assume is the preload)  It is -0.015, which sounds small to me, but I will ask when I talk with them.

For pistons, I have them listed as flat, 4.285, Diamond.  I do not have the Part number, and will ask for more information.  I am assuming these are the something like the 51910, but these are listed for 4.280 diameter.  Forgive me for not knowing how to read the measurements.  These would be 2618 alloy if I am not mistaken.  I will ask.  If I read the -0.004 correctly, they are 0.004" below deck.  Rods are RPM I beam (I do not have part number).

I will keep people posted on what I learn.

[Cooter]

I've heard good things bout Diamond pistons as well.

[idahogrumpy]

Diesel sound? Wheres the ignition timing? Same distributor as when run by the builder? Lean? same carb?  If MM built it and broke it in would they have not heard the same noise? What changed after it left the builder? Forged pistons are noisy until they warm up.
Grumpy

[cudaken]

Diesel sound? Wheres the ignition timing? Same distributor as when run by the builder? Lean? same carb?   If MM built it and broke it in would they have not heard the same noise? What changed after it left the builder? Forged pistons are noisy until they warm up.
Grumpy

Grumpy, if the cam lopes are going flat or the spring seats going bad, it does take some ware time. While MM had the engine it could have sounded fine. Then there is the chances they will think the engine sounds fine now with the way they built it?   My L22665F forged pistons never sounds like that, but they have a longer skirt than the diamond pistons I think.

Cuda Ken

[XH29N0G]

I spoke with MM, and they listened to the recordings.  Their opinion was that it was not something to be concerned about and that it was a consequence of the parts they used (along the lines of what some of you have said).

I am comfortable with this response.  If for some reason I am wrong, I will know sometime in the future.

[firefighter3931]

If MM is OK with it then you should be too 

One other thing ; you're using what looks like the stock style stamped tin valve covers correct ? 

A thicker solid aluminum cover will lower the volume a lot more vs the sheetmetal style and quiet down the valvetrain noise.


Ron

[c00nhunterjoe]

Wow. 1st ones sound like a 6.2 gm diesel. Sounds much better with the 20-50