Inliners International Forums General Discussion Hi Performance valve tapping sound on 292

I have recently built a 292 for my 53 chevy p/u, lumps/ported polished/70cc head/I used Lp pistons,262 crower cam, mallory distributor, backed by a saginaw 4 speed& hayes clutch, all is balanced and harland sharp roller rockers 9:5:1 true comp ratio,, motor runs awsome tons of power but I have a valve tap sound that you can hear in cab, we have adjusted the rockers cold,hot and running, but I still have this sound, I never used roller rockers before,, are they noisier than the stamped rockers?? Im just looking for some advice,, please help..any info please help..

What oil are you running?

What is the pressure?

What brand cam bearings?

Tlowe I talked to you yeaterday about the guide plates, Im using royal purple breakin oil ,, i believe its 10-30w and we used a zinc additive, pressure between 40-50 psi and not sure on cam bearings,

cam bearings were federal mogul

Roller rockers are louder than stock ones.

Does the sound seem to be just one? Or a few or all?

Can you describe your lash method?

What kind of exhaust manifold/header are you running. I had a noise in my 270 GMC I thought was vale train related. I readjusted everything. I changed the lifters, push rods, rockers and rocker shaft. I checked the valves and valve springs. I could not quiet the noise but I knew the valve train was OK. Years went by and I changed to cast headers from tube headers and the noise went away. Just a thought. Beater

I have tom langdons exhaust headers,

thanks beater thats kinda of what I started to do , changed lifter and pushrods, Im wondering if I go to a heavier oil down the road after breakin that it may quiet down, currently Im using royal purple 10/30 breakin oil,, not sure just a thought

One question no body asked. Are you running a hyd or a solid lift cam? If is a hyd cam you really should be hearing anything from the rockers.My soild cam ran a .022 clearance and once the cover was oh you could hardly hear them.And you surely didn't hear in the car.Next question i have how was the cam gear installed?(is it a alum gear) If it was not heated before it was installed It may??????????? have walked off the cam some and this will make the cam walk back and fourth and this is what you mit be hearing????????????
Another question is are you sure all the rockers are getting fully oiled.Have you looked to be sure all are oiling and not running on the dry side?

twisted, its a crower stage 3 hyd cam (262, the gear was heated when we put it on, the rockers have plenty of oil none are on the dry the side, today I was listening to it as it ran and I tried to take off oil fill cap and there was so much vacuum I couldnt get the cap off until I shut the motor off, never had a motor do that before,

there was so much vacuum I couldnt get the cap off

I don't know what that is, but I don't like it.

Are there any breathers or a PCV valve?

Be certain it wouldn't come off because of vacuum. Remove the cap and place the palm of your hand over the fill hole.
Before you mention the crankcase vacuum I was going to ask if the noise might actually be the PCV valve snapping. Forget that question. It sounds more like the PCV valve is missing or is bad with the pindle stuck in the middle of its travel.

High manifold vacuum at idle should pull the PCV nearly closed, allowing only a small amount of fumes to be pulled from the crankcase.
In addition to that you need a way for fresh air to enter the crankcase. I'm not offering you an option. You need fresh air in, so the manifold vacuum can pull the crankcase fumes into the engine and burn them. You obviously don't have a breather cap or there wouldn't be a vacuum issue holding it on.
Most 292 valve covers have a hole, drivers side front. A tube from that hole connects into the carb air cleaner. That way the carb air filter also filters air going into the crankcase.

Before you started the engine, did you check the rocker geometry and clearances for the spring and retainer, the rocker stud and the stud boss?
With the Crane aluminum rockers I had to machine the boss down lower because of an interference problem underneath.

there is a PCV valve, no breather cap, just a regular oil fill cap on valve cover, geometry and all clearances were good, Im gonna look into a breather cap today.

The post from Richard, CA, made me think of problems I've had with other engines, with valve parts hitting the valve cover - rockers too big or pedestals not machined down far enough.

Have you tried running the engine with the valve cover OFF?
It's not THAT messy if you don't rev it and just for a few seconds, or you can cut the top out of an old valve cover and use that. Then you could see what is going on in there. If it stops making the noise, you've found the problem!

deuce,
I had the valve cover off, nothing hitting, oiling good, adjusted the valves while running, Im gonna try and turn them down another quarter to 1/2 turn to day and see what happens, like I said earlier it runs awsome and has a ton of power, just that dam tapping, I even pulled the flywheel cover off to see if somethings hitting or?? Im gonna take my wifes stethescope up today and see if I can localize it better,, thanks for responding..

I hate it when the nurse leaves little oily rings on my chest because her husband used her stethoscope to listen to his noisy engine.

I did have a ticking that developed on my 292 with crane rockers at about 10k miles. The noise came in real slowly so it shouldn't be the problem you are having.
When I had rebuilt the engine the stock pushrods turned out to be a good length and they were all in good shape so I used them. They were the stock one-piece with the rolled ends.
One of the pushrods had broken some pieces loose around the hole and had gouged the steel insert in the rocker. The pushrod end was jumping around in the pocked instead of rotating and swinging smoothly.
I found a guy with a partial set of SBC Crane rockers that used the same steel insert and was able to replace it. The other rockers were still good, but the other pushrods were starting to show roughness around the hole.
I replaced all the pushrods with the style that have the machined ball inserts on the ends.
Three years later and still going good.

Yes that is another good question I ran into this same problem with the gold crane rockers hitting the valver. I just doubled up the gaskets and that took care of that. But i also had way more lift. But it's still something else to look into.Also check the ends of the valve cover They could also be hitting there as well You will see rub markes in if that be the case.

I have had the valve cover off numerous times and there are no marks on it, when we put it together we cleaqranced everything and had no issues that way,,

If you can find a stethoscope, you could better isolate where exactly the noise is coming from and this could narrow down the problem for you.

scpousn,

Have you made any head way with this?
I missed the Kempton show.
I'm in Douglassville, PA.
Wish I could say I could ride up there and listen and tell you what it was but funny noise diagnosis is not my strong suite.

I was wondering if it could be a small exhaust leak?
Sometimes the after market intake and exhaust manifolds or headers are a tight fit at flanges.
So when the intake and exhausts get torqued to head there's less than zero clearance and one or both may want to flex back away from head.
This leaves a small clearance, and a leak.

For me, on my 292 it was the headers and Offy intake with leak on bottom side of center runner leaving me wonder why car would start just fine until the couple squirts from accel pump were used up.
Of course the cure is to grind a bit off the flange of the offender where it butts together with other manifold.
Hope this helps.

Pete (MM2USN)

Pete,
thanks for the info, definately not an exhaust leak, motor runs awsome just has that annoting tap, truck went to the body shop today for some sheetmetal work, dam noise drove me nuts, when we get it back to the engine shop we may just tear the head off, not looking forward to do that but got to figure it out, Dam thing runs great with a ton of power, gonna take a closer look at geometry, maybe I need to make a set of pushrods up?? not sure..gonna star scrounging for another 292 head in the mean time to have a backup.. thanks again,,

craig

To all thanks for the info, talked to mike ravenswood today and he was with Leo, I posed my problem with the noise and it looks like he gave me the answer, when I put my motor together I used stock pushrods with the roller rockers, mike and Leo confirmed the need for a longer pushrod than stock,, Im gonna be working on the truck next week when I get it back from body shop,, thanks to all who tried to help..

craig

I had a tapping sound in my '94 S10 Blazer for about 4 years. I and a mechanic looked for it to no avail, checking plug wires, using a stethescope, and so on. The mechanic thought it was a noisy injector. Ran great all that time. Finally decided to change plugs and such recently. The first plug wire I started to pull to change the plug was not on the plug solidly and the spark had been jumping the gap to the plug all that time. The moral of the story is to check plug wires both by pushing (which we did) and pulling (which we didn't). No more "tapping" sound.

Rocker arm length needs to be decided by how the roller tip is contacting the valve tip. At minimum lift and then again at full lift.
This is not as big of a problem on these inlines as it is on a SBC. The valve angle is much less for the inline and keeps the valve inline with the rocker roller much better at both extremes of lift. Tom

scpousn,
Thanks for the update.

I'm a bit confused.
Are they saying that if you use roller rockers you're going to have to plan on buying longer pushrods?

Tom,
It sounds like you're saying the contact point of the roller on valve stem should be checked as part of the build?
Maybe the stock pushrod length works, maybe not?

Pete

Longer possibly, any change from stock, such as sinking the valves, longer valve stems, aftermarket rockers, etc, can and will affect geometry and the contact point on the valve stem. I needed pushrods that were longer on my 292 build.
Lots of good info on the Comp Cams site, as well as this board.
I strongly recommend you get a checking pushrod (Comp sells them) and a light weight checking spring and discover what length gives you the correct rocker geometry and valve stem contact.
I got my custom pushrods built by Smith Bros., very fast service.

Incorrect geometry and wrong pushrod length by itself will not cause any noise.
The primary benefit of correct geometry is to achieve maximum lift from the cam.
A secondary benefit is reduced friction and valve stem wear.
Maximum lift at the valve occurs when (1) the valve stem and (2) a line between the rocker pivot and the valve stem tip are at 90 deg. That should occur at mid lift. Cam base circle and max lift will be on either side of that 90 deg.
None of that will cause noise unless the geometry is way off and something is hitting something else. The noise would not come from the geometry problem itself.

Don't be so quick to ignore an exhaust leak. I hear suggestions of a stethoscope, but I don't hear follow-up on that.
Either a cheap stethoscope or a 2-3 foot long wood dowel.

Another thing you have been ask and not answered is if the noise is from one valve or several.
If the rocker geometry is off on one rocker, it will be off on all twelve, unless you have some extreme dual profile cam with high lift.

The primary benefit of correct geometry is to achieve maximum lift from the cam.
A secondary benefit is reduced friction and valve stem wear.

All OEM engines reverse this priority, and bias the geo against mid-lift to reduce scrub.

First let me say I really do appreciate the info, that being said the truck is at the body shop and will be there for another week as I stated above, I have not had an oppourtunity to get to it on top of that Im in the process of retiring from the Navy ,so it maybe a couple of weeks till I work on it,, I will post my findings,, thanks

I've had a fuel pump spring on a sbc get weak and allowed the pump push rod to bounce and make a hell of a racket. Not sure if a 292 could do this or if your even running a stock type pump.