roscobbc

489 cu in - Brodix Race Rite oval heads - Edelbrock Air Gap - 950 cfm DP.
Take a listen to this fella's - 4/5 years after new build-up and 1800 miles or so. Howard hydraulic flat tappet cam - roller rockers - comp lifters. Oil pressure 70lb+ on cruise. Engine runs fine. Noise on video started recently and following a 'heavy duty' run out with 'the boys' has become far worse. Adjusted lifter preload several times - starting with 1/2 turn, 3/4 turn and finally 1 turn. Stripped valve covers off after last run and double checked preload once again. Noise on video is far worse than video indicates. Have I got a 'failed' lifter? - noise seems far too high on engine to be big ends (and oil pressure is too good) - Noise starts at around 1800 rpm through 3000 rpm and eases off (or seems less noticable)at higher revs. Any thoughts/ideas/similar experiences guys?

hugie82

That's an exhaust leak!

hugie82

Check your manifold / header gasket at the head. If you have headers, buy regular stock exhaust manifold gaskets! They're cheap, easy to install and last forever because they don't blow! If they leak you usually can just tighten it up and its gone....

roscobbc

Thanks for suggestion Hughie - not a header leak - definitely a mechanical noise.

TedH

Valves/springs/guides?

Super6

Sure sounds like valve train. Here comes the "shotgun" approach. Oil pressure sounds good, but is oil actually coming up the pushrods? Sounds like dry metal on metal. Or rockers hitting the inside of the valve covers? Does this engine have aftermarket roller rockers, if so, only 1800 miles or more? Other than a "Hard Run", no parts changed recently? Could a few valves springs be broken. Lobes going on the cam and/or the bottoms of the lifters are damaged? Something has happened that's is lowering the pre-load on the lifters, like a lot of wear suddenly. Stick a magnet in the oil lately?

I would buy a cheap set of valve covers and cut the top half off, just keep enough on the lower top side to contain the normal oil spray from the pushrods/rockers. Run the engine and literally see what is happening. I wouldn't run this engine any more than necessary to determine the problem.

Les

If you've eliminated an exhaust leak (including under the car), I would guess it's somewhere in the valvetrain. Get a buddy to work the throttle for you and use something like a breaker bar that you can seal against your ear while putting the other end against the valve cover. Go from rocker arm to rocker arm while he holds the RPMs in the noisy range. If everything is healthy you should hear a mechanical whirring type sound- that's the best way I can describe it. If not healthy, the difference in sound will be obvious as will the location of the problem. I just did this with my breaker bar yesterday on the valve covers and bottom of the oil pan, and all sounded good.

roscobbc

Good ideas guys - have checked out the valve springs - all OK. The idea of the stethoscope (breaker bar) against the rocker cover is a valid one - problem is that the noise isn't really that evident when the car is stationary - I don't have any friends that would be brave enough (read crazy) to do this on the roll

Super6

The whirring noise comes from the fact that the lifters and pushrods on rotating. You could do the stethoscope thing with the engine idling. You're not looking for the dry rattle at idle, but listening for the whirring noise. If you find one that sounds different than the rest, then that is a place to look at with the valve cover off. Take the valve covers off and put a spot of white paint on the pushrods just below the rockers where you can see them. Run the engine at idle and see if the pushrods are rotating by watching the white marks. This is what I was doing with the $30 valve cover set that had the tops cut open. You ought to be able to have a 2nd person rev the engine above 1800-2000 to see and hear what is going on. You wrote that it started at 1800rpm. Look to see if all of the pushrods are rotating at this 2000 or so rpm. Also, look to see if all of the rockers seem to have the same amount of stroke.

While the valve cover is off, pull a few pushrods while those lifters are on the base circle. And see if they are straight. Start with No. 1 on the compression stroke. Check the 2 No. 1 pushrods. If OK, re-install and set the preload. Mark your balancer every 90 degrees. Rotate the engine 90 degrees and you're on No. 8, check those pushrods and re-install and set preload. Another 90 degrees on the crank and you're at No. 4, and so on. Just follow the firing order and 2 x 360 and you're back on No. 1 again.

cv67

Got something going on there for sure

Start it up with the valve covers off dont worry about the mess.

Bet you find it quick

had something that sounded very similar and it was the rocker arms as they grew with heat "just" touching the intake side of the valve cover

it took some very strong flourescents to see it. Cant tell you how many times I adjusted the valves wondering what it could be lol.

Ground it down all was quiet as a mouse!

Almost sounds like a single part at valvetrain speed slapping on something or too much clearance. Roll your pushrods on a glass table top just to do it.

roscobbc

Took the intake manifold off at the weekend


looking a bit closer and found this! -



It seems too coincidental that this was the reason for the noise - I had lost the spanner a while ago (possibly about the time I installed the engine!) - no reason to think that it would move around too far in there - if it did fall-in would it have been pushed-out by a cam lobe when rotating - or - if it had fallen down would it have jammed against the side of the cam. Inspecting the spanner it didn't look as though it had been damaged in any way. Will 'pull' lifters and rotate cam to if these is any damage.

AZDoug

Food for thought:


If your wrench bouncing around on the cam wasn't the cause of the noise.....

I picked up my '72 pretty cheap because it had lifter noise, and the miss at idle made me think a cam lobe was possibly going flat, or at best a lifter was way too loose.

Well, I found the loose rocker arm, tightened it down,a nd noise went away for a while, then came back. Most likely cam lobe going bad.


I took off manifold,and inspected all lifters. All looked perfect.

Then I started looking at pushrods,a nd found one that the ball was wearing away and was 1/8" shorter than the rest.

I went to my spare parts pile and put in a new (used) rocker arm and pushrod, and no more problems.

You could possibly have bad rocker, or pushrod, if it isn't a cam lobe

Doug

REELAV8R

That's hilarious. Now you'll have a performance increase due to weight reduction.

CanadaGrant

Are you running a mechanical fuel pump? Sounds like a bad lifter but...?

roscobbc

That had crossed my mind - wouldn't fuel delivery be an issue if fuel pump pushrod was badly worn.
Removed lifters tonight - all look fine - can lobes initially seem to be OK - I'll rotate engine later this week and inspect each lobe - also have a closer look at pushrods.Not too sure of best way to check-out for collapsed/failed lifters though.

roscobbc

A good buddy of made a 'connection' between me doing this and a King Dick brand spanner lol!