Let’s Tune This Engine

[Grumpy]

while Im sure your able to hear things that don,t come through clearly on the video,
I watched the video and listened and don,t hear anything I think is indicating a problem.,
now to be sure Id visually inspect every one of the rockers, valve springs, guide plates etc.
and look for clearance and geometry issues, but from the very limited video you look ok.

 

[DorianL]

Hm. Interesting. Surprisingly, the audio of the video is quite accurate. There’s nothing more to hear.

Maybe this is just normal after all for the set up that I have ? I guess I’m expecting the valve train to be as quiet as OEM and that’s just not going to happen. I read somewhere that these significant changes (full roller rocker, aggressive roller cam, etc.) will be inherently noisier.

Then there’s just that vacuum issue.

 

[DorianL]

Here I took the cut open valve cover off. Maybe that was enhancing the sound ?

And EDIT, I am not able to press down on the pushrods after I shut down.

 

[rlphvac]

I’m sure you’re right. I tried again wasn’t able to do it. Brian fart. I can press them in quite easily when they bleed down tho

I read those Summitt responses for the Comp Cams and most of them said that they could collapse them by finger pressure I know that you don't want to hear this but get them out of there its still winter so have your ride ready 100% for the springtime suffer once and be done with it

 

[Thunderbolt]

Where exactly are you reading the vacuum? Near/in a runner? Maybe use an other vacuum port?
On my 350 with 106 LSA cam vaccum reading was more stable near the carb vs the port located in the runner where my brake booster was attached.

 

[DorianL]

Where exactly are you reading the vacuum? Near/in a runner? Maybe use an other vacuum port?
On my 350 with 106 LSA cam vaccum reading was more stable near the carb vs the port located in the runner where my brake booster was attached.

I tried both from the carb and from the intake manifold (brake booster). The needle vibration looks identical

 

[DorianL]

I’m less worried about the noise than I am about that needle vibration. (The noise could be me being paranoid and expecting too much from a modified engine.) There can’t be too many things that can cause that. Unless something has changed since a few months ago when I was reading a stable 14.5, it must be something I did. The only things that has changed is the cam and lifters.

 

[DorianL]

Interesting. I just read that full roller rockers “make a clicking sound from the clearance between the rocker stud and the ID of the rocker pivot.”

To check, one can, with the engine off, can to see if you can move the whole rocker ass'y from side to side. If so, that's a likely explanation.

I definitely noticed that with the engine off, I can move from side to side the rocker that amount that the pushrod guide plate clearance allows. That kinda surprised me.

Hmmm. That does make sense. That would also explain why putting the tip of a stethoscope to any of rocker studs reveals a distinct clacking sound for each. If it had been a lifter... not all of them would be making that noise. In this case, pretty much all the studs sound the same.

 

[DorianL]

I’m kinda satisfied with that explanation for the noise.

Now to figure out that vacuum needle vibration. The last thing I want to do is burn a valve.

 

[Grumpy]

btw sound is only one of several indicators
when looking to find for isolate a valve train issue,
experience helps here,
obviously you need to measure accurately during assembly first.
just place your thumb on each rocker adjustment jam nut as the engine idles,
youll feel a click, as the rocker slot impacts the impacts the rocker stud if thats an issue
,rather than hear it if the rocker body is just barely touching.
put your thumb on the retainer and press down at idle,
youll feel the retainer touch the rocker body if thats an issue.

the vacuum gauge needle dancing may be due to reversion
on most performance cams the valve timing overlaps
if that needle bounce smooths out by about 1500 rpm its most likely related to valve timing overlap and not a mechanical issue

 

[DorianL]

Will try that !!

 

[DorianL]

the vacuum gauge needle dancing may be due to reversion
on most performance cams the valve timing overlaps
if that needle bounce smooths out by about 1500 rpm its most likely related to valve timing overlap and not a mechanical issue

OK. Now that’s fascinating!! Super fascinating. So this could be normal after all.

I’m quite sure it smooths out by 1,500 rpm.

That’s a huge relief.

 

[DorianL]

It never occurred to me that those vacuum readings might not apply to performance cams. Of course they are meant for diagnosing stock configurations.

What a relief.

 

[busterrm]

I agree, I had to do something on mine to get the rocker/retainer clearance. Mine has 1.6 rockers, each rocker was not contacting the retainer, but I was not happy with the clearance I had, so I did a very small amount of clearancing on the underside of the rocker. Basically, the CompCams Ultra Pro Magnum 1.6 are a great rocker, but right where the arm of rocker and the trunion of the roller bearing come together is square, so I used a cartridge roll and rounded that area a little bit. Thats all it needed.

 

[DorianL]

I agree, I had to do something on mine to get the rocker/retainer clearance. Mine has 1.6 rockers, each rocker was not contacting the retainer, but I was not happy with the clearance I had, so I did a very small amount of clearancing on the underside of the rocker. Basically, the CompCams Ultra Pro Magnum 1.6 are a great rocker, but right where the arm of rocker and the trunion of the roller bearing come together is square, so I used a cartridge roll and rounded that area a little bit. Thats all it needed.

I’m still not 100% comfortable with the sound and I beginning to think you’re on to something.

You’re saying the rocker might be contacting the stud here



And I might clearance it with a dremel or just get other rockers.

But how did you figure out it was contacting there ? When I look at my rockers, I see no evidence of contact. I’ll remove one again and check the stud.

 

[DorianL]

Incidentally I did run a vacuum

the vacuum gauge needle dancing may be due to reversion
on most performance cams the valve timing overlaps
if that needle bounce smooths out by about 1500 rpm its most likely related to valve timing overlap and not a mechanical issue

Putting my finger on the rocker stud, I can’t really feel the clacking. If Busterrm is on the money, it must be just contacting.

I did run the vacuum test up to 1500 rpm. As the rpm climbs, the needle’s oscillation amplitude narrows significantly; like to an inch of vacuum or less @ 1500 rpm. The vacuum also moves up to 25 inches.

 

[busterrm]

It never occurred to me that those vacuum readings might not apply to performance cams. Of course they are meant for diagnosing stock configurations.

What a relief.

How much is the needle bouncing Dorian?

 

[DorianL]

When up to 1500 rpm ? It’s like 25 inches and maybe an amplitude of 1 inch. Possibly even a little less. The needle pretty much trembles.

I also pulled a rocker and found no evidence of contact with the stud, nor any possibility of contact. The rocker will hit the poly lock before it bottoms out.



Sliding a long valve cover nut in there, it bottoms out on top before the bottom.

If I put a stethoscope to the top of each poly lock, I hear clacking that almost sounds like slapping.

I guess it’s either junk lifters (Comp Cams shame !!!) or the clearance between the pushrods and guide plates. The stethoscope sounds comes across as very distinct. It’s hard to believe it could be the pushrod/guide plates.

Here’s what I think
I think this is normal but noisy operation of Comp Cams lifters. I suppose I could try a thicker oil... but at this point I’m leaning toward new lifters

On other hand, I don’t want to buy lifters just to find the problem is still there. These puppies are expensive.

 

[Indycars]

I think Bob was talking about the clearance between the bottom side of the rocker arm and
the valve retainer. Location "C" in the photo below.

 

[DorianL]

It clears it well.