Crahm

As some of you might know. I've been working on my '69 427, installing rebuilt heads and rebuilding the distributor.
I yanked the electronic ignition back out and reinstalled the points and it the engine fires up and revs very nicely.
Last Friday, i took the car for a test drive and took it to the upper rpms in first gear. Wasn't gone too long and as i raised the hood in the garage, i had an intermittant "clacking" noise coming from deep in the engine.
This week I adjusted the valves while running and the clacking noise went away.
Today, i buttoned up the valve covers and took if for a test drive. Thought the timing was a little too advanced so i pulled over and tweaked it a little. Engine was sounding fine and it drove smoother.
I romped on it in first gear and as I went to shift to second, power was way down, so i took it easy and putted home. As I lifted the hood, the "clacking" noise was back.
It is not consant, but more often than not at idle.

The other thing which is differnent, is that i changed the oil, and installed 10w/40 synthetic oil vs Castrol 20w/50 conventional i was using with old worn heads.

Can I be losing oil pressure in a lifter because I switched to synthetic?

Thanks for your ideas.
Charles
Dallas, TX

ronarndt

Most likely cause is not your oil. I assume you have hydraulic lifters. Twice your valve lash had to be adjusted after you high revved the engine and put more stress on the valve train. The adjusting nuts on one or more rocker arms are loosening up. Do your rebuilt heads have new rocker studs? Cheap fix is to add a locking nut to keep the adjustment where you put it. Better fix is to replace the rocker studs and maybe also the rocker arms so you have a locking allen set screw integral in the stud. Or just don't rev that 427 and drive it like an old woman

Crahm

I installed Com Cams roller rockers, with the locking allen set.
Last thing I did was ensure all allens were tight before installing cover.

drwet

I'm not real knowledgeable about big blocks but I had a thought for you. Do you have screw in rocker studs? Press in studs can work themselves loose and do what you describe. The other thought is whenever I have installed roller rockers I have had the ends of the rocker studs milled square to give the set screws a flat surface to seat against. Otherwise they have a tendency to work loose.

L88Plus

How are you tightening the poly locks? If you tighten the nut, then tighten the allen screw, you're not doing it right.
Get it preset where you want it, then back off about 1/16 to 1/8 turn (you'll have to mess with this to get it right). Now tighten the allen lock screw down, then TIGHTEN THE ALLEN LOCK SCREW AND THE POLY LOCK NUT TOGETHER, TURNING BOTH THE NUT AND ALLEN SCREW AT THE SAME TIME.

GUSTO14

Charles, what kind of oil pressure are you seeing? Before and after the switch to synthetic.

Have you been able to isolate the source of the noise to one or more of the lifters? If the same ones are making the noise, it possible you have a bad lifter, or possibly some debris got into one and is not allowing it (them) to drain back in a timely manner.

If you decide it may be the lifters, you might consider a set of anti-pump up lifters such as Rhoads Lifters. I've used them on a number of engines now with "performance" hydraulic cams with great success.
http://www.rhoadslifters.com/

Good luck... GUSTO

Crahm

After the first test drive, I was idling the engine in the garage and listening for the noise with a stethoscope and couldn't peg it, other than I thought it was coming from the passenger side, forward.
I decided I'd adjust the valves with the engine running (had set them statically after head and rocker installation).
I had to tap my allen tool with a hammer to get the allen screws loose, so they definitely weren't backing off, thus I don't think the poly lock had moved.

Thought? Could the new valve springs be so strong they are putting some kind of higher than acceptable pressure back on a lifter which is worn and driving oil pressure out quicker than the pump is replacing the oil?

When I turned the motor off last night, it was making the noise. Should I be able to find which pushrod is too loose right now?

Oil pressure is 40lbs plus at idle when hot, higher when cold.

MelWff

when you are adjusting the valves, how far beyond zero lash are you turning the nut, a 1/2 turn or more? why did you switch oils, did you have the problem before switching?

Crahm

After static adjustment to cinch up the twisting movement of the pushrods, I turned the nut 1/2 turn.

I changed to the synthetic oil because I have weeping oil around the front seal. I'm hoping the synthetic will swell the seal - a process of questionable benefit, some swear by it, others don't.

No, prior to oil, head, rocker, and distributor rebuild, I never had the clacking sound. The previous heads had very worn valve guides, thus I would puff a little oil smoke.

One thing I'm going to try to find out today from the head rebuilder:
What is the seat pressure of the valve springs he installed?
Did he use any shims?

I'm thinking my next moves are:
Change back to Castrol 20w50 conventional.
See if clacking goes away. If not, adjust the valves again, while engine is running - this is what caused the clacking to stop the first time.
Next, drive the car like I"m driving Miss Daisy for an extended period of time, such as an hour on the highway, stopping from time to time to check for clacking - maybe if there is debris blocking a lifter port, it will clear through.

ronarndt

Yes. If anything, it will be looser because the engine is cold. You had the valve lash increase twice after you had the rockers adjusted. It would be helpful to know if the same ones were loose both times. Why the valve lash is increasing is still not explained. You have rockers with locking adjusting nuts, so that rules out one cause. You did not state whether your reconditioned heads have the old rocker studs with fifty year old threads which could be worn enough to allow your adjusting nut to loosen, even with the allen lock. Or as drwet mentioned, they could be pulling out. Hydraulic lifters work by using the non-compressible physical property of oil to make the lifter work almost like a solid lifter. Unless the lifter is completely broken I would look for another cause. They usually go just the opposite- the miniscule amount of oil that actually goes into the lifter with each lifting cycle does not get out the relief valve and the lifter "pumps up", the effective length of the lifter gets longer and the valves do not close and "float". I would suggest going back and re-adjusting the valve lash (engine cold) with someone watching over your shoulder to check. If you do not have the cylinder top dead center each time you will not get valve lash accurately set. Are you mixing a new camshaft with the lifters from the previous cam, or visa versa? Anything unusual about your reconditioned heads? If changing oil was an issue, thousands of people would be having this problem. RA
An afterthought- you posted while I was still writing. You did not have this problem until you changed to your reconditioned heads. In order for the valve lash adjustment to stay where you set it, the tolerance between the threads of the rocker stud and rocker adjusting nut (and lock) must be close enough so the nut will not slowly spin and loosen as the rocker and pushrod beat against it thousands of times. Did your re-builder have the rockers you used while he was doing the rebuild? Did he rebuild your old heads or are these completely different heads? Did he change the rocker studs? Press in type or screw in type? Something is allowing the adjustment to change as the engine is running. BTW- put me down as a non-believer for synthetic oil curing your front seal leak problem. There used to be a tool available that you could use to push the old seal out and pull a new seal in with just the oil pan off. It worked like Chinese handcuffs to grip the new seal. Haven't seen one recently, but see if ebay has one. That will stop your oil leak.

Crahm

The rebuilt heads have new rocker studs. I'll ask the builder what springs he used.
While engine warm, but off, I used the simple static valve lash setting of the engine at TDC number 1, adjusting 1 and certain other cylinder's valves; then rotating to TDC for number 6 and adjusting the remaining valves.
It is simple enough to pull the valve covers and adjust the valves while running, i just have a hard time hearing when the rockers get loud because this is a side pipe car, thus loud exhaust.
I certainly have the same thought as you regarding a change of oil being doubtful as the cause, but it is such a simple thing to try first before opening the engine back up.

ronarndt

Well, by now I would be saying a few choice words, if it were my car. You have covered all of the step-by-step diagnostic steps and still no good answer. I had a similar problem many, many years ago with a 55 Pontiac 287 cu in V8. One rocker nut would keep backing off, I would re-adjust it and it would back off, sometimes so much that when I took off the valve cover, the rocker was sideways and the pushrod was just loose in the head and the engine was running on 7 cylinders. Back when I was a teenager with no money to fix it the right way.

CanadaGrant

This one is a long shot. I changed over to a mild Comp roller cam with their rockers and spring set on my 69 427 L36. I noticed that using the stock valve covers I would get a slight tapping noise like a lifter on each side depending on how warm or cold the engine was and it would come and go. It turned out that one rocker on each side was just touching the tin oil baffle that is spot welded inside the valve cover. It would come and go as the sheet baffle was heated or cooled and sounded like a lifter. It showed up as a slight scuff mark on the tin. Worth checking for. Other than that, I would check for cam lobe wear if you can't keep them adjusted.

Crahm

Thank you for the idea, but I am using tall valve covers.
While engine was running and adjusting the valves, the noise was present, meaning no valve cover on.

Scottd

Im going to going to go in a different direction here.

Last year after a short block swap, I was getting horrible top end noises. I reset my valve lash 4 or 5 times but couldnt fix it. I consider myself a pretty accomplished garage mechanic, but I threw in the towel and took the car to a local speed shop. Turns out I made a total NOOB mistake and had the timing SO far advanced that it was causing all my issues.

So, while this may no be your problem, it may be worth getting out your timing light and getting an exact timing measurment (to at least rule it out)

REELAV8R

One thing that the 10w40 synthetic probably does not have is the generally accepted minimum of 1000ppm of zinc. The 20w50 probably did. If you want to use synthetic I would recommend 0w40 Mobile one as a cost effective alternative. 1000PPM and a true synthetic not a highly refined dino oil. about $25 for 5 quarts at walmart.

If this is a flat tappet engine reduced zinc may cause excessive lobe wear on the cam.
Another thought is that you stated that it generally is coming from the front passenger side of the engine. That is where the fuel pump pushrod is located.
Same rule for PPM can be applied to wear on the fuel pump lobe on the cam although spring pressure is quite a bit lower so less likely. In either case try listening to the fuel pump area next time and see if the sound can be heard there.

L88Plus

Try rattling the pushrod up and down rather than spinning it. If everything is perfectly matched, it'll continue to spin well past zero lash.

I've heard of piston slap, but never lifter slap...

MotorHead

Change back to 20W50 and see if the noise goes away. One thing I take into consideration when building an engine is the oil clearances and type of oil I am going to use. I would build an engine a little looser ( mains, rods etc. ) with 20W50 and I would not change to a different oil.

mikem350

All good suggestions...but its not the oil causing the problem(s).

I adjust lifters by carefully spinning the pushrod for no clearance (not tight) just touching. Then 1/2 turn and tighten.

stc315

I had similar problem years ago and it was cam lobes being wiped out by heavy springs and lack of zinc in the oil. Used full synthetic w/o zinc during cam break in and cam didn't break in properly and it wiped out the lobes. I now use Valvoline VR1 w/zinc.