ENGINE GURUS: Need advice with diagnosis of excessive valvetrain noise(!)...

[J Banning]

Before you say "check to make sure your cam ain't wiped", here's the scenario...

I did a cam/lifter/spring swap (all new parts) along with the addition of ported stock heads w/stock valves and stock GM head gaskets. I then put it back together with the rocker arms and pushrods that I had previously used (both ok - checked for straightness & cracks).

Now I'm experiencing what I consider to be excessive valvetrain noise. I've head of some lifters or injectors being "noisy", but there's no way this can be that. The noise appears to be equal across both heads (ie: no central point), is not RPM dependant, and did NOT happen prior to cam/head change. I've pulled it all apart, and short of measuring everything with a caliper, I see nothing wrong.

- Oil systems was fully primed (I'll post details if wanted).
- Oil pressure was 65psi @ 2500rpms. 20psi @ idle.
- The teeth on the cam sensor are ok/no wear.
- The same with the cam gear.
- Timing chain is ok.
- Front cover is ok.
- Cam button is new GM, and ok too.
- No play in rocker arms or pushrods.
- Cam and lifters have no unusual wear patters on them.
- Lifters spin freely in bores.
- Oil galley plugs are still in place for lifters.

I'm out of ideas, and almost out of patience. I will be taking the parts to the machine shop this weekend for inspection. Prior to that, I'd like some other thoughts/opinions from you guys.

What could be the cause?

Thanks in advance,
-Banning.

 

[Intercooler]

Banning,

Did you check your pushrod length with the new cam? It may have changed enough to do this. I also had a bunch of noise with my 218 so maybe it is just par for the course using it!

 

[J Banning]

Pushrod length was NOT checked. I was told by the supplier that all other stock parts would work. I will double check tonight.

Installed spring height and pressure WERE checked.

-Banning.

 

[Steve Wood]

You HAVE to check preload....

Having said that, yours will probably be dead on, but I doubt it.

Some of these cams seem to be noisy due to the ramp geometry.

 

[J Banning]

Originally posted by Steve Wood
You HAVE to check preload....

1) Yes... the load at installed height was 115# @ 1.70". It was measured and checked.

2) I know that some of these cams/lifters can be noisy, but this wasn't one of those "hey, can you hear that noise... I think it's the valvetrain". It was more like "holy sh#t... dude, what the h#ll is making all that noise!?!?!".

There's something wrong here. Any ideas?

-Banning.

 

[Steve Wood]

No, pre-load!

how far are the pushrods depressed into the lifter?

 

[Intercooler]

Originally posted by J Banning


1) Yes... the load at installed height was 115# @ 1.70". It was measured and checked.

2) I know that some of these cams/lifters can be noisy, but this wasn't one of those "hey, can you hear that noise... I think it's the valvetrain". It was more like "holy sh#t... dude, what the h#ll is making all that noise!?!?!".

There's something wrong here. Any ideas?

-Banning.

#115# 1.70" is your spring pressure on the seat which is a total different can of worms. Your preload should be .030"-.040" when measured (pushrod length and the amount it presses into the lifer). FWIW my 218 was noisy until I sold the motor. Sounded horrible but the damn thing ran great! Did you use Comps lifters? The guy I sold the motor to I suggested that he throw them in the trash and try GM's to see if it quieted it down. It may be just the ramp of the cam and is something you have to live with to run the 218. I can't tell you how many times I had Frankg listen to my car because the noise scared me! Still hauled ass but noisy!

 

[Intercooler]

Any update?

 

[NEARING]

Bobby, let me know when you want to pull your cam, I'll give
you a hand. I could use some Buick TR wrench turning practice.

 

[Chuck Leeper]

NOisey??

I agree w/ Steve W. The cams are ground differently than stockers.
In order to increase the lift, cams are ground w/ reduced base circle dimensions. Since the stock length p. rods are made at GM w/ a known cam circle dim, then changing cams to a different lift, requires different length p. rods. Assuming not having adj. rockers.
Base circle dims and overall lobe dims are also confined to what will slide thru the cam brgs!!

Bottom line... check the preload.. I'm betting there is little to none.
Ps: think one of the "AZ gang" tried the GM lifter change and got nowhere???

back to huggin my T&D's!!!

 

[Chris Taylor]

I can tell you the the T&D's will not resolve the noise issue. It may be more noticable. I like the adjustable rockers but they have some noise. In this case they may help.?

 

[J Banning]

Update:

All the lifters I has used (comp cams) were completely pumped up all the way to the retainers. From this you'd think (as my machinist did) that the pushrods may be short. I had him check one of the pushrods with a $700 digital veneir (sp?) caliper and it measured 8.765". I believe that he said that according to his info, that pushrod was short. He said that suppliers such as Sealed Power sell several different lengths. I could try that once I measured preload.

I didn't have a feeler gauge on me to get exact measurements, but I did a quick check of lifter preload. I dropped a couple of lifters and pushrods in place on the base circle of the camshaft, and tightened up the rocker arm assembly. My rough measurements showed that I had .030 - .050 of preload. I'll get exact measurements today.


WTF????

-Banning.

 

[bob86gn]

Banning,

Did you ever get this resolved? I have a similar problem. A week before Cecil no less.

Bob

 

[frankg]

Always 100% of the time you change parts in these engines, you have to check for proper length pushrods!! The proper way is get an adjustable length pushrod, put it in and turn that cam lobe 180 degree from highest point of the lobe, slowly lengthen the rod until you have zero lash( no play up and down ) then take it apart and have the rod measured and add whatever preload you want to that length and thats the size pushrods you need. You might want to measure a few different lobes and get an average. I'd go with .030-.060 of preload.... Oh yeah my 212 CC makes some noise also Frank

 

[J Banning]

Sorry for not posting a followup on the thread.

What happened? Well like I said, it looked like I had .030 - .050 of preload so I put the bit#h back together It's been running ever since, and it got much quieter the second time I started it up. Why? Uh... I'm not really sure. All I know is that the engine was very noisy when I broke the cam in... I'm talking LOUD! I tore it all down, re-lubed it, checked the pushrods and lifter preload, and put it all back together. Once started, it was MUCH quieter - just like it sounds now if you can manage not to focus on the exhaust leaks and misc. squeaks & clanks

However, it's NOT running 100% perfect at WOT.

Not sure if you've been following my other threads or not, but I've got a problem where the car runs very rough at anything over 5200 RPM. If I have the exhaust open, you can hear it stutter all the way down the track (INTERCOOLER can vouch for that - he heard it). This has been going on since I put the engine back together and at first I thought it might have been problems with the injectors/fuel/chip. I let if go because I just wanted to run the car. Lately I started looking again for the cause... mainly at the chip setup, and now the grounds.

I just got done checking all the grounds, replacing the battery, and putting different battery cables on the car. I'll test it tomorrow night. If that's not the fix, then I really don't know any more. Maybe it all points back to the pushrods?? Possibly what I'm seeing is valve float?

Like I said, I'll be testing the car again tomorrow night. If the problem hasn't gone away, I'll pull the valve covers and check everything under there again to be 100% sure.

Sorry to ramble on here. I hope you can get something out of this??
-Banning.

 

[brew]

something to think about

your performance at WOT may be due to your noise. The detonation sensor (ping) will retard the timing. That's why we can run aout any grade of gas we want and get minimal ping.

Also, valvetrain #101---In theory, anything in the valvetrain that creates noise, costs power.

Brew

 

[J Banning]

Nope. I have ZERO knock at WOT and no timing retard. And yes, the knock sensor works.

Thanks anyway.
-Banning.

 

[bob86gn]

Thanks for responding Banning. My buddy's dad has been a mechanic for 40 years. He told me to start it and let it idle for a while since I did not change the cam or lifters. He said that the car sitting for 6-8 weeks could easily have caused the lifters to drain down and it may take awhile for them to recover. I'll wait and see, in the meantime I will order adjustable pushrods today to check my preload. I love my car!!!

Bob

 

[J Banning]

Question: If I didn't have ENOUGH lifter preload, would it cause the high RPM miss/stutter I'm seeing now (anything over 5200RPM)?

Keep in mind that it pulls very well to 5000 - see sig (1.54 60' with 5# launch)

-Banning.

 

[EightSecV6]

TOO MUCH preload will cause a stutter at elevated boost/ rpm levels.If you are using a good lifter and have a bunch of oil pressure, the lifter will keep the valves open(stay fully pumped up)when the lifter is on the base of the cam. Comp lifters take a good 20-30 minutes of running to get the air out(big noise at break in). They are called ZERO LASH lifters which means they are to be set at zero (or very very little)preload. They perform extremely well at high RPMS but you have to deal with the noise. Remember if you set them at .030 preload on the base of the cam, and it is fully pumped up (as a Comp lifter will be) you just opened a valve .030, the problem is more prevelant on the intake side when boost is helping to push it open.The big advantage to thes is more valve lift when the lifter is over the nose of the cam. I have pulled my hair out over this exact problem you can:
A: Put GM or lo-po lifters in it
B: Turn the boost down to band aid it (not an option)
C:Shim up the shafts to .000-.010 or use adj. rockers (adj pushrods are JUNK imho)
Good luck!
Bill

See you guys at Cecil....we may be bringing a surprise project with us, look for it (if we dont kill it on the Dyno tommorrow!!!!)