My possible rod knock *VID*

[Sirone]

Sounds like a valvetrain noise.

 

[StinkinLincoln]

its hard to tell without being there.
a buddy got a 88 z28 w/ a rod knock, paid $500 so he didnt care. drove it to show a tech at the place he works at and it sent the piston through the oil pan. it had a slight deeper tap than a rocker problem you would expect and a real bad clacking noise w/ rpms, he had a feeling it was a rod/piston problem.
i know how you feel, i just got 650 miles on my 331 and im tearing it apart to figure out why my bearings are ate up.

 

[StinkinLincoln]

and from the vid, im leaning toward a
bent push rod or a out of adjustment rocker, undo all the valves, let it sit for 5min to make sure all rollers are bled and adjust all of them, you can roll the pushrod on glass to see if its bent. and see what happens, i cant help w/ pedestal, i have studs.

 

[go-stang5.0]

been years since I have heard a rod knock so I cant really comment on that. But it does sound like valvetrain. Did you get ped. or stud heads? I cant comment on ped. heads as I've never had them on my car since I've owned it. But yea a loose stud mount rocker can do that. Did you make sure to back off the allen locks in the rocker retainers before adjusting? and then tighten down the locks afterwards? I guess you couldent check the lifters but you may have a bad one. Also, if a pushrod is bent you may not see it with your eye but if you roll it on a glass table you will know right away.

 

[juiced_94gt]

Pull your valve covers and check the RRs to make sure they are not loose.

I have re-adjusted the rockers already, and NONE were loose

wow that does not sound good... to me it sounds like a lifter tap r rod knock... pull the valve covers and check your RR's

I sure hope it's a lifter, i ordered new ones and new pushrods just to make sure.

Definatly a valvetrain noise. Sounds like rockers set wrong to me. Do them over and if you don't know how to properly do it, have someone help. Check for bent pushrods too.

I will triple check the geometry and re-start it before pulling the motor.

+1 on valvetrain noise.
A rod hammering would have a deeper tone than that.
It's not any better for you but it could be a wrist pin or broken piston.
Sounds like the engine is going to have to come back out. How many miles are on it?

1k on the motor i hope it doesent have to come out, a piston problem sounds like that too?

I vote rockers!! And that is a good thing if u dont have to tearn down the whole engine. Just get them tighter and I bet it goes away!

I wish they could just go tighter, i torqued them to 23 FT LBS like stated in the hayes book.

 

[reddy351]

So, are they pedestal mount or stud mount? I'm assuming pedestal, as you mentioned a torque spec. Pedestal mount ones need shims to make the adjustment. Too many shims and you get valvetrain noise. Too few, and you get valves hanging open.

Has it made the noise for the entire 1000 miles?

Wristpins/pistons slapping sound a bit like that. I was going to say earlier though that the noise seems to be slower than engine speed. (Cam runs at 1/2 crank rpm.) Kinda leans me to the valvetrain. That should be good for you.

 

[juiced_94gt]

Dude it's a RR, I swear I just went through the exact same sound a few months ago. Where exactly do you live? I will come out and readjust your valvetrain if your willing to help... I'm not kidding either. Put you hand directly over where the sound is comming from, your going to feel it.
The weekend is my only good time. Let me know. Ohh yeah you have to buy the beer and pizza.

I live in Fontana, I will also pay for your gas if you come and help me figure this out, plus all the BBQ you can eat and ALL the beer you can eat plus bring your wife or G/F to keep my G/F company. This is why i love stangnet, it's better than friends sometimes.

Since you have already checked your rockers and pushrods the only way to find out would be pulling the motor apart I'm afraid. You can get a stethascope (I'm not sure about my spelling) and check different areas on the block and around the timing cover to isolate where the noise is coming from but it sounds like a internal engine problem to me.

Who built the engine? I see that it is a CHP 331 street fighter from one of your earlier threads but was it a stroker kit or the complete short block. The fact you still have oil pressure is encouraging. How did the compression test turn out? I hate that you are having this problem seeing how you spent a good amount of money on some nice parts and you haven't got to drive it much. This could still be fairly minor but but it more than likely is in the bottom end of the motor.
It was a CHP Street fighter shortblock built by CHP im 05' so it's out of any kind of warrantee if it had one.

Good luck!

been years since I have heard a rod knock so I cant really comment on that. But it does sound like valvetrain. Did you get ped. or stud heads? I cant comment on ped. heads as I've never had them on my car since I've owned it. But yea a loose stud mount rocker can do that. Did you make sure to back off the allen locks in the rocker retainers before adjusting? and then tighten down the locks afterwards? I guess you couldent check the lifters but you may have a bad one. Also, if a pushrod is bent you may not see it with your eye but if you roll it on a glass table you will know right away.

I got ped. heads, i will take the pushrods and roll them on glass to make sure they are not bent.

 

[juiced_94gt]

So, are they pedestal mount or stud mount? I'm assuming pedestal, as you mentioned a torque spec. Pedestal mount ones need shims to make the adjustment. Too many shims and you get valvetrain noise. Too few, and you get valves hanging open.

Has it made the noise for the entire 1000 miles?

Wristpins/pistons slapping sound a bit like that. I was going to say earlier though that the noise seems to be slower than engine speed. (Cam runs at 1/2 crank rpm.) Kinda leans me to the valvetrain. That should be good for you.

They are ped. heads, they have NO shims because they reached the torque spec at 1/4 to 1/2 of a turn, im under the impression that you only need shims if they do not reach the torque spec within 1/4 through 1 1/2 turns. at least thats what i was told.

 

[Adam95GT]

I live in Fontana, I will also pay for your gas if you come and help me figure this out, plus all the BBQ you can eat and ALL the beer you can eat plus bring your wife or G/F to keep my G/F company. This is why i love stangnet, it's better than friends sometimes.




I got ped. heads, i will take the pushrods and roll them on glass to make sure they are not bent.

Rember glass is a liquid... let me know what size pushrods you are using i have a extra set of stock size...

 

[juiced_94gt]

Rember glass is a liquid... let me know what size pushrods you are using i have a extra set of stock size...

what brand?? how many miles?? stock is what im using but im going to measure again just to make sure.

 

[go-stang5.0]

Rember glass is a liquid (true)... huh

Most large glass panes (such as on a glass table) are cooled floating on a bed of liquid mercury. Coincidentally that glass is one of the truest flat surfaces next to a machinists table, which most people dont really have at home. So if theres even a slight bend on the pushrods you will know.

 

[WHITE94COBRA]

Just a shot in the dark but do you have stock valve covers?

 

[Adam95GT]

speedpro brand new... in box... my friend picked them up for the engine im building... but they didnt match the rods that came out of the set up... or the rods poka gave me.... the poka rods and the ones from the inital build up that we broke down were the same... so im gonna use that size


just dont use old glass

 

[final5-0]

I went back and listened to it again and you know I think everyone else is right it does sound like a very loose rocker but I am a little bit puzzled. A pedestal mount rocker that is tightened and doesn't come loose can't create extra clearance on its on unless a pushrod bends or flattens out on the end correct?

Sounds Like VT to me

Well ... Anything can happen and remember, the valve train is working at
great speed

I'd have to say that ped or stud mount makes no difference if something
goes wrong within the rocker or lifter.

It boils down to ... too much slack somewhere and we are now
hearing the slap of parts against each other

IIRC ... he said this happened just after he pushed things really hard

I'd isolate to the bank and if the sound is at the front, back, or middle

You can use a long stick, screw driver or a stethoscope or help with
being more precise.

It will make a mess
but
If worse comes to worse

A F T E R you isolate the noise ...........

You can fire it up with the vc off and get a close and personal look

Good Luck

Grady

 

[BlackVert]

my mechanic has a valve cover he cut the top off of to help him be able to watch and mess with the valves as the car is running. it helps keep the mess down. something like that might be useful here ...

 

[WHITE94COBRA]

I believe he is using his stock valve covers, I doubt he has taken the splash guard inside of it out, that will make a RR tap for sure. All the rr has to do is loosen up a bit and it'll tap that, most RR wont fit under them in the first place, unless they are the comp pro mags. That's why you see alot of fox VC's on our cars.
What size RR's 1.6's or 1.7's? Either will touch, one just more than the other.

 

[juiced_94gt]

I believe he is using his stock valve covers, I doubt he has taken the splash guard inside of it out, that will make a RR tap for sure. All the rr has to do is loosen up a bit and it'll tap that, most RR wont fit under them in the first place, unless they are the comp pro mags. That's why you see alot of fox VC's on our cars.
What size RR's 1.6's or 1.7's? Either will touch, one just more than the other.

I have fox v/c's that have the oil baffles removed, the rr's are 1.6 FRPP, they should be ok and when i looked at the VT none had any of the anodize removed.

 

[Pokageek]

"know how you feel, i just got 650 miles on my 331 and im tearing it apart to figure out why my bearings are ate up."

StinkinLincoln - not to get too far off topic..wth happened to yours!!?? That's terrible. Sorry to hear this.

Juiced..do you have any sort of warranty on this? It still does not sound like knock at all to me. I once had a car with knoock and it didn't sound like that..my experience.

Now..my rockers (stud) were not adjusted right ..in fact they were way off and they sounded just like that. Find someone who can double check your work . That's what I do anyway. Hope u get it worked out.

 

[juiced_94gt]

Well i changed the lifters and pushrods and re-torqued the rockers, AND started it with the V/C's loose to lift each side with the motor running and same noise....NOW IM PISSED!!!!!!

 

[Terdfurgason]

Im no expert but here goes...

I had a similar noise coming from the passenger side VC, so i thought. Someone mentioned that the Twisted Wedges have some chatter and its normal. The car wasnt running good at all then found a vacuume leak between the Upper and Lower Intake manafolds. Took it apart, added a spacer for good measure and new gaskets. Car runs much better and the "Chatter" is gone. The sound mustve been air seeping in the gap.