gimme some ideas on the noise in my wee bit of a rat

[harshman]

Lately I have been listening to a tin like rattle in my 396 when the rpms get above 1500 ‘ish. Thinking that it was the valve train I just pulled the intake and replaced all the lifters (perhaps a faulty lifter on a freshly installed 292H cam package). Started it up and for the love of Mike it is still there. It almost sounds as though the rocker is tapping the valve cover. I took off the driver’s side cover and installed a cardboard shield and tried it again and it is still there. It sounds like it is towards the front but I don’t think it is a lifter that hasn’t pumped up. I’m wondering if it may be up in the timing chain or balancer?

[Norwoodx55]

I've had some header leaks that I was convinced were valve train related. Try poking around with a stethescope or section of heater hose to pinpoint the source.
Brett

[harshman]

I tried that with a stethoscope and it sounds more internal. That and I have siliconed the gaskets to the block and headers.

[Foudie]

For some reason I remember saying something about the balancer on numerous occasions but you kept on saying that it was the valve train and that I should just shut and mind my own business.....hmm....looks like I am right again Andy my boy!!!

[Rubes]

I too have a 'knock" on my brand new 396. It started shortly after breaking in the cam. It is front and center and almost sounds like a sloppy timing chain hitting the front cover. I've already diconnected the waterpump, removed the fuelpump pushrod, checked all the lifters, checked for exhaust leaks...etc. It sounds much harder and deeper than a lifter "tick".

For some reason I remember saying something about the balancer

Whats the issue with the balancer???

[harshman]

I have no idea if it is the balancer or not. It is the same as you say – harder and deeper than a lifter tick. So deep it makes me guess that it may be the balancer but it has the ticking pattern of valve train. I was also thinking of pulling the timing chain cover and looking for anything there. I just really don’t want to go through all that if I don’t have to.

[Rubes]

Ha...I was hoping YOU would do it so I dont have too I got so disappointed with this that the car is for sale with the knock and a spare 454 to go with it. If anyone cares, its the 68 Caprice in my vBGarage, $5k come and get it!!!

[harshman]

I’d sell the 396 in a heartbeat. I want to get me a 450 hp small block and be done with it.

[paul67]

Baffle plate in the oil pan ? was a new oil pump fitted, if so is that hitting the oil pan as on boyds hot rod show.Rubes have you hydr lifters, as a friend found that the break in compound stuck the lifters had to flush engine out as found oil starvation to the lifters.
paul67

[Rubes]

Paul...yes I got Hyd lifters. In fact the short block was assembled (bagged with desicant to keep it dry) for a year before finally getting to finish it. So you may have something there.

But like I said, right now I'm concentrating on another project, and this is for sale. I may try the flush. how did you accomplish that?

Rubes

[paul67]

You can buy an engine flush or as a friend uses about a pint of petrol mixed into the engine oil an ran for 20 mins, have had him do an engine for me and it worked stopped the noise. Myself I would use a flush, if you go the petrol way don't have smoke while your waiting.

[myclone]

While noises are the most difficult to diagnose over the net I'll throw some things at you that Ive seen before that had me pulling my hair out but may give you some ideas or a direction to go in..

1. Rods/rod bolts barely hitting the oil pan which usually happens with stock pans and aftermarket rods like Eagles or other cap screw set ups or if the crank has been swapped with the wrong one or a stroker piece (this is less metalic than a rod knock but more "tinny" sounding than valve train clatter and deep in the motor).

2. Crank counter weights barely hitting the pan or even weld beads from balancing on the crank hitting the pan. (same/similar as #1 as far as sound).

3. Crack in the flex plate but usually is more prevalant at the back of the motor and under the car (sounds like a rod knock too).

4. Timing chain/cam gear rubbing the front of the block and usually happens when the press in style oil galley plugs are replaced with screw in NPT plugs.

5. Timing chain rubbing the timing cover which has happened with less than high quality stamped covers (usually those el cheapo off shore chrome POS pieces).

6. Crank/rods hitting the windage tray (BTDT way more times than I care to admit).

7. Rockers hitting the valve covers (prolly not the case here but if you have cast valve covers instead of stamped it may be worth a look since cast covers have a diff sound when being whacked by the valve train).

8. Piston slap/rock which Ive seen on just a single cylinder from a mismachined piston and the builder not mic'ing each piston/bore before assembly (it happens unfortunately when ppl get in a hurry or lazy).

9. Wrist pin galled(sp?) from detonation which opens up the wrist pin to piston pin bore clearance. This usually takes many miles of detonation to occur but detonation isnt not always the cause so dont rule out that the manufacturer didnt goof on one or more piston/pin machining since some manufacturers can be pretty sloppy in the QA dept.

To all but rule out 8 & 9 I would crank the valve lash down on each cylinder to hold the valves off the seat (one cylinder at a time) then fire up the motor to see if the noise changed or went away completely. Killing the cylinder pressure on a noisey cylinder can usually make the noise change or go away completely which is way easier/cheaper than yanking the motor, tearing it down, and mic'ing every thing.

Id have to go back and re-read your post but Im assuming you disconnected all the belt driven accesories with no change? How bout disconnecting the torque converter from the flex plate (assuming youre running an auto)? Torque converters can make some baffling noises when they are bad or going bad. To rule that out just remove the three bolts holding it to the flex plate, slide it back away from the motor all the way into the front pump in the trans, and fire it up. It wont hurt anything and will eliminate anything causing the noise in the drive line/trans/torque converter.

Hope some of this helps or at least gives you some ideas to persue.

[Rubes]

Thanx Clone

I thought of most of those things. I did diconnect all belt driven accessories and the torque converter. I even took out the fuel pump pushrod, since it is deffinatley more noticable dead nuts front and center.
The motor is all stock with stamped valve covers, original front cover and most internal parts, no windage tray, forged TRW pistons. By the way, mine makes the noise all the time, Harshman seems to have the noise only above 1500 RPM, so they are prolly not the same issue.

Thanx for the input

[harshman]

Brian (Qship) came over and he thought it may be front accessories. I pulled all belts and still the ticking. I think I will locate a pro builder and pay to have him diagnose this one. I’m stumped.

[Rubes]

If ya ever figure it out, before tossing the motor in favor of the small block, please let me know. But we both know it is going to be something WAY different than what we are expecting right? I remember once trying to track down a noise in the dashboard on a friends Fiero...had the entire thing dismantled just to find it wasn't there!! Few weeks later, he found the front shock was loose, and that was it.

good luck
Rubes

[Steve Chryssos]

What do you have for rocker arms? You no doubt have 1.550" diameter valve springs and probably have aftermarket "roller bearing" rocker arms. Frequently, the rocker arms need to be aligned properly by cutting, grinding, bending or banging on the guideplates. Sometimes you may even have to take a die grinder to the underside of the rocker arm where it contacts the valve spring retainer. This is especially problematic on big blocks that have canted valves.

So. Bump the motor while checking each rocker arm to see if the roller ball remains in good contact with the valve tip throughout the lift range. You can also pull each rocker and checking for wear marks. Also check out the pushrods where they may be contacting the guideplates. Even if the geometry is correct, the body of one of the rocker may still be hitting the retainer and therefore require a wee bit o' grindin'.

You changed the cam and the noise started. So I'd start here. At least check this out before spending money with an engine builder.
/Steevo

[yody]

well i am suprised no one else thought of this, but check the fuel pump pushrod, if it is too short it will make noise, or if the cam lobe got worn out where the pushrod rides on. Also make sure there are no dents in the timing cover where the timing chain could hit, also you sure its not detonation?

[Rubes]

well i am suprised no one else thought of this, but check the fuel pump pushrod

... removed the fuelpump pushrod...

one of the first things I looked at cause it sounds so prominant in that area. I did consider detonation since it only had 87 octane in the tank right now, but at idle? with only 12degrees of timing??

Rubes

[harshman]

fuel pump push rod is the next thing on the list. It is a new cam and I sure hope the lobe aint flat. Timing is set at 32 total and no sign of detonation. Timing chain I think I’ve ruled out because it the sound starts after about 1500 rpm or so.

[Rubes]

Do you have a cam button? could the cam be walking forward and rubbing the cover? I put mine together too long ago (as well as too many others in the mean time) to remember if I had one in mine or not.

Rubes