Did I burn the valves?

[TheBirdistheWord]

I broke in my motor (stock l20b bored .40 over with A87 head) with the valve clearance set to a tight .011 exhaust and .009 intake, I didnt verify proper clearances and thought it was .010 exhaust and .008 intake, thinking I was setting the valves loose with my settings.  I have rectified my mistake by setting valve clearance to proper spec but I fear the damage has already been done.  I am now experiencing light valve chatter, barely audible from the cabin, but none the less there, gets a bit louder at operating temp but its not violently loud.  Plugs still look good, with a golden brown color albeit they have gotten darker since the last valve adjustment, power hasnt been affected, idles with a slight fluctuation, in fact setting them to factory spec woke it up and smoothed it out.  First start with castrol 30w and I am currently using delo400 15w40, I have only used Wix filters, and just did the second to last oil change for the break in process (1000 miles.)  The valves have only been chattering for the last 250 or so miles, and I use 89, should I consider using premium only?  Should I consider going to a 20w50? I not one for magical chemical solutions to my car problems, but seafoam has done me solid when trying to alleviate valve issues with past vehicles, could a seafoam treatment possibly help?

 

Thanks in advance

 

EDIT: it just occurred to me the carb could be the culprit as well, I doubt it because I installed a jet kit from Top End Performance, but I wonder if a little more jet tuning would be necessary to completely eliminate the chatter by delivering the fuel at a more suitable combustible mixture?

[MicroMachinery]

It looks like you're doing everything right. As long as you're not pinging or detonating, I wouldn't switch to premium gasoline. I wouldn't seafoam the engine this early on. Just continue breaking it in. I see no reason why you should have a burned valve. As the engine continues to break in and "loosen up", it will continue to run differently. I would keep running the 15w-40. Don't sweat the small amount of valve clatter, as most Datsuns I've heard have a slight amount. It's when you run too tight that you start having issues..

[Sealik]

Stock cam?

[datzenmike]

0.010" and 0.012" hot setting. If you set this on a cold motor you're going to be slightly loose is all.

 

Keep an eye on the valve lash for a few thou miles. If there is any wearing in of the valves it's upward into the seats and this decreases the valve to rocker clearance. In other words the valves get tighter. Just watch them for a while.

 

Delo 400 is fine.

 

Seafoam is for basket case motors. I wouldn't use it unless it was the last option. If your motor is looked after and kept in tune and given oil changes you won't need it, so avoid additives.

[TheBirdistheWord]

stock cam, full rebuild from the crank out, before the head went on I adjusted them to .008 and .010, obviously that was a cold adjustment, which is fine.  I than adjusted them to the aforementioned tight .009 and .011 @ 100 miles then ran it like that for another 500, adjusted again to the same spec for 800 miles.  I did notice the valves tighten up during this time re-adjusted them one by one over this period, and for the last 250 miles it has been adjusted to .010 and .012.  All adjustments done hot besides initail start up

 

so, basically its most likely a combination of it being old tech and fresh rebiuld still breaking in?

[MicroMachinery]

I would wager. As long as you have good oil pressure, you're not overheating, and it's driving as well as it sounds like it is, just run it. I wouldn't sweat a little valve train clatter. It is old technology, like you say; it's not going to sound like a new car, even if it is a fresh rebuild. Is this your first time building/breaking in an engine?

[datzenmike]

Does the 'rattle' come and go or get louder or softer?

[TheBirdistheWord]

This is indeed my first time building and breaking in a motor solo, I have been "around" for complete builds in the past.  Oil pressure is at a consistent 60psi while running, and 24 to 30psi at idle depending on how hard I push it and for how long.  Temp sensor gauge stopped working around the last valve adjustment, but up to that point it would go a bit high but I have gathered that is pretty normal with new builds, never made it close to the red.  The rattle seems to fade upon any amount of throttle, and return at the very end of deceleration.  My old motor had piston slap on all 4 cylinders, so I am familiar with what a "bad" noise sounds like.  This noise seems to join the other car "clatter" when it is under any load, but as I stated it is still audible from the cabin once the rpms smooth out as if everything is tapping very gently and quickly, doesnt get worse or louder with higher rpms, just quicker if that makes sense....

[Sealik]

Well......If it was mine.

I would check how the cam is contacting the rockers......any abnormal wear???

All the "small steady springs" on each rocker clipped into position?

You said it's a stock cam.....but...I wonder if the wipe pattern is centered?

Who knows......'sound's' like a lobe could be running off the rocker etc.

Easy to do.....

Cam lobe up....remove oil from rocker with rag and mark each side of the face of the rocker with a felt pen.

At least an 1/8" up on each side.

Rotate engine/cam lobe on rocker...pattern should be centered.

Repeat.

....................Process of elimination.

[datzenmike]

Could be chain rattle too. The chain is 'loosest' at idle. There is a chain tensioner that has an oil feed hole in the back. As the motor revs and the oil pressure rises, this helps add extra pressure to the tensioner and may quiet it. Worn or stretched chain or chain guides may do this. Too thin oil or in need of a change may also do this. Not the end of the world if only chain rattle.

[TheBirdistheWord]

ahhh, I hadnt thought of doing a wipe pattern test, ill get to that soon....  the lobes visually look fine, no excessive wear or anything, rocker springs are all good as well.  I am on a fresh oil change with delo400 15w40.  I changed it anticipating it might be the problem, it is defintely not coming from the front of the motor,  I suspect it doesnt have to do with he chain but I am still considering dumping this oil for some 20w50 to see if it quiets it down any.  chain is new, guides are new, tensioner is new...

[datzenmike]

15W40 is plenty thick. Thicker oil isn't fixing a problem it may just hide one. This assumes that there even IS a problem. A little ticking is normal on a L series. Probably just valve clearance and better clearance than no clearance.

[banzai510(hainz)]

I do mine .006 and .008 cold. if that dont quiet it up nothing will.

Unless you got a bigger cam and not telling us on the valve train spec and parts(if stock you should be Ok)