My 1979 g30 motor traveler (camper /rv) has 5.7/350 engine w/93k miles .when cold start (after sitting for wk or 2 wks ) makes a loud tapping noise under 1 valve cover ,once warmed up totally goes away. Should i be concerned ,any suggestion or info is appreciated . .

 

Welcome from Florida. Sounds like you have a sticky lifter. I would try one of the lifter cleaners/oil additives. It will probably get worse if you do nothing.

 

maybe its piston slap.

 

I'm sure it,s not a sloppy piston ,runs good ,no smoke .

 

i have had a ton of small block chevy cars and trucks.....this is what i do and it works every time....some may say NO but i swear it works...time for a cleaning..first.. before your next oil change ( when your about a quart low....old chevys usually lose a little oil between changes..) put a quart dextron trans fluid in your oil. its zero weight and really detergent...run that for about a week. then get some motor flush and 5 quarts of rolleta diesel motor oil...follow the directions on the motor flush then fill motor with the rotella oil ( diesel oil is very detergent also ) do that for the next couple oil changes and the valve tap should go away....you may even see your oil pressure get better as well

 

my 2000 sierra had it. never burned a drop of oil, no smoke, ran fantastic.
slight light knock when cold if you drove of immediately...idle 30 seconds all good. gm has bulletins about it.