Hanging valve?...NO, and another update

[Pentroof]

Recent build, 390 with Edelbrock heads, morel roller lifters, adjustable Ford iron rockers, PI intake. Motor is in a nice 1970 f100 I built for my daughter. My initial valve setting was one full turn after zero lash.

Maybe 5-600 miles on the motor. It has run fine, but always ran a bit rich at startup. Once it started getting cold here, I noticed it started sounding real fat with a bit of a burble. I finally modified the EFI tables to lean it out a bit at cold startup. Oddly, that didn’t make much difference. It got worse as it got colder.

Finally, I decided to investigate a little more and listen closer as the motor was warming up after a dead cold start. What I hear is the distinctive sound of a valve (or two) hanging open, not a fat burble. Once the coolant temp gets above 125 or so, it starts to clear up. At temperature, the motor runs great.

So, it seems I have one or two valves that are a bit tight? Haven’t pulled the covers yet, but looking for other ideas and things to look for before I reset the valves. I thought about pulling the plugs before it gets to temp and look for a couple wet ones. If it was distinctive and only one or two, I would back off the adjuster 1/4 turn on those.

With hydraulic lifters, wouldn’t they have to be REALLY overtightened to overcome the full travel?

[My427stang]

What are you running for oil? Could it be too thick and pumping up cold?  Usually valves stick hot usually if dry or overheated, not cold

Morels can be a bit fussy with too thick of oil, could be your issue.

[Pentroof]

I’m aware, I run 10w-30 VR1. I don’t think anything is “sticking”, I believe there is too much preload on a couple valves. I think it relaxes as the head grows. I think it’s that close that a few thousands of expansion allows the valve to seat.
I’ve had this happen before on a Pontiac that my dad had set the valves on. In that case, it was an all iron motor and the valve was being held open AFTER it warmed up (pushrod growth) I was able to determine which cylinder it was simply by running it with the valve cover off on that side and loosening the rockers as it was running.

[fryedaddy]

every fe i have had is or was cold natured.if you rev them any at all before warm up period they make all kinds of noises.i sold a 390 fairlane one time in the middle of winter.when the guy picked it up he just cranked it and took off down the road and stomped the gas pedal and it backfired and made some horrible noises.he turned around and came back and said,whats wrong with this thing.i said let it warm up,you cant run it that hard cold.he let it warm up then he called me on his way home with it and bragged on how well it ran after it warmed up.you may have something wrong with your 390,but they are cold natured,especially in the winter

[blykins]

There's about .100-.125" of travel in a traditional, standard travel, hydraulic roller lifter.   I've seen some guys struggle with getting the pushrod lengths correct on short-travel lifters with non-adjustable rockers, but unless you really messed up on pushrod length measurement, I don't see it hanging a valve open when it's cold. 

[Pentroof]

There's about .100-.125" of travel in a traditional, standard travel, hydraulic roller lifter.   I've seen some guys struggle with getting the pushrod lengths correct on short-travel lifters with non-adjustable rockers, but unless you really messed up on pushrod length measurement, I don't see it hanging a valve open when it's cold.

I know, that’s what I don’t get...and I have adjustable rockers! There should be no way that I got that much preload. It absolutely sounds like it though.
Listened to it again this morning and put my hand up to the exhaust. Sure enough, nice strong puff associated with the stumble. Once the temp is beyond 135, it purrs like a kitten...clean and smooth.
I was just looking for input on what I could be missing before I pull the covers.

[blykins]

Could just be cold natured.   If the valves were hanging WAY open, it would be hard to start.

[My427stang]

There's about .100-.125" of travel in a traditional, standard travel, hydraulic roller lifter.   I've seen some guys struggle with getting the pushrod lengths correct on short-travel lifters with non-adjustable rockers, but unless you really messed up on pushrod length measurement, I don't see it hanging a valve open when it's cold.

I know, that’s what I don’t get...and I have adjustable rockers! There should be no way that I got that much preload. It absolutely sounds like it though.
Listened to it again this morning and put my hand up to the exhaust. Sure enough, nice strong puff associated with the stumble. Once the temp is beyond 135, it purrs like a kitten...clean and smooth.
I was just looking for input on what I could be missing before I pull the covers.

Any chance it's something silly like a marginal plug wire, cracked plug, cap with an issue when cold or damp? 

If it is hanging up, do a cold compression, or even better, leakdown test, it'll show immediately

[Falcon67]

I have a medium sized Howards hydro roller in the Falcon's 351C running Howards lifters.  It's more a race car that what you're talking but it still is "off" until it gets near the 180 operating temp.  Off like almost one or two dead or partially dead cylinders.   After it's fully warm and ready for battle, runs good.  But cold, it's just...grumpy.  10w30 oil, lifters the standard 1/2 turn down from zero lash. 

[Stangman]

If you went 1 full turn down on the adjustment why dont you back them off a quarter turn. 3/4 turn should be plenty.

[cjshaker]

Are you sure you're not getting icing on or in the carb? Not an uncommon problem on older engines that have had the heat risers and hot air plenums taken off or blocked, and it leads to a bad idle and poor performance. I used to have to start my old 390 and let it run for about 5 minutes, then shut it off for about 10 while some heat soaked into the carb and got rid of ice formation, then it would run fine.

[Pentroof]

If you went 1 full turn down on the adjustment why dont you back them off a quarter turn. 3/4 turn should be plenty.

I hear you. .050” should have put them in the middle of the plunger travel, but I obviously F’d up at least one. And it runs so well once at temp, I’m convincing myself I either stopped for a beer and added another turn to one or just got way off on determining zero before adding a turn. Not like me to miss the basic stuff, but I’ve had my moments.

I have a laser temp gun arriving tomorrow to determine if it’s just one cylinder and then I’ll back that one off. Otherwise, I think I’ll just start completely over and reset them all. At this point, I’ve spent more time talking about it than getting off my ass and doing something.

I’ll report back what I find. Thanks to all for the comments.

[Pentroof]

Are you sure you're not getting icing on or in the carb?.....

No carb on this one! 

[Stangman]

Maybe you should start from scratch, it might be something that needs to be checked regardless if your not sure. But if you want to play around with your temp gun thats fine. Depending on how long the job is and how hot it is the beers add up. . Been there.

[GerryP]

No carb on this one! 

The throttle body blades can still ice.  When you're running possibilities, you don't rule out anything until you see it for yourself.  In that regard, run the engine as CJShaker pointed out.  If it makes no difference, then you can rule it out.