What's the smoke from the valve cover holes coming from?
I get zero smoke of any color from the exhaust pipes, even on cold startup. The engine has been rebuilt (have no idea who or when) and it's got a rumpety cam in it, and the caps are stamped.

I put new valve seals on when I went through the heads. They're the type with clips around them. I have a PCV going to the carb on one side but an open baffled hole on the other. Having trouble finding a grommet that'll fit the cover AND the breather.

Are the valve guides leaking and burning oil? Why wouldn't there be any smoke coming out of the exhaust if that's the case?

Sounds like oil vapor making its way from the crank case. If thats all your seeing I wouldnt worry bout it.

Thanks Jeremiah
Man, that's a lot of smoke to be recirculating back into the carb through the PCV.
I guess it just bothered me because there's no windshield to keep it from blowing back into my face.
;)

Smoke smells like ______? As suggested, could be water vapor or could be blowby since engine has been rebuilt and either rings aren't seated or the engine has not been ran for some time.

Water?!?! Don't say that! Looks and smells like smoke.
Engine hasn't been run in quite a long time until that last couple weeks. I'll get a breather on it so I don't have to see it anymore. Out of sight, out of mind.... but that might mean out of sight, into shop.
:)

Not good Joe. Pull all the plugs, do a compression test. Write all readings down and then spray oil into each plug hole and repeat. If readings go up significantly, it's toasted rings. Or if the initial reading is real low, same thing.

Yeah.... fun, fun.
I'd think that it'd be coming out the tail pipes though, right?

Yeah, that's the rub. But there's not too many things that cause blue smoke. Rings, guides, no baffle on PCV valve, ruptured (hate that word) trany vacuum modulator, bad intake gasket seal at the bottom side (valley),,,, what else????
And smoke out of the breather eliminates the modulator and intake gasket,,, and even the PCV baffle. So,, you did the guides. That leaves,,,,,
Could be a cracked piston too, like my '61 348 (350hp-tripower) But that laid down enough smoke to obliterate the neighborhood.
OH, check for Olly plugs.

It's white.... not blue. Well... if it is blue, it's super light. The exhaust is clear.

I don't have the modulator hooked up yet. That'll be tonight.
I've got a PCV valve plumbed to the carb, so there's only 1 hole in the covers now. It'll be interesting to see the plugs.

White, I thought you said blue. My bad. White is water.
Well, if it's not coming out of the tail pipe and only the valve cover then it's not a head gasket or cracked cylinder wall. That leaves the intake gasket on either side of the thermostat. Yeah, that's about it. Check your dipstick. Foamy white?
I'd also be looking at the plugs. Real clean ones have been steam-cleaned. That's a leak there.

I see that you know to check the plugs, sorry. And I think white can also be ATF. You said it smells like smoke, so,,,
but you said the modulator isn't hookup yet,,

Think about it, the motor is a sealed unit, the valve covers are the highest part of the motor, the heat has to go somewhere which is up, I'd say it's just condensation from the hot parts and oil under the covers and nothing to worry about. too.
I've pulled an oil cap off of an LS1 with low miles that had a bunch of milky green crap under the cap, it was just from condensation.
You do need to make sure that your PCV is correct for your motor and all of the other valve cover seals are doing their job.
It wouldn't hurt to do a leakdown test if you have the spare time.

Guess I got a few more things to do under the non-existent hood before I venture too far.
But that's why I built the thing! If it was all good, I'd be bored spending all my time with a margarita on the deck.

I'm gonna do all those checks.... I still need to finish lashing it anyway. The timing is perfect and the carb rebuild seems to be working stupendously. I didn't notice that the oil pump was anything other than a stock replacement, but looks can be deceiving. I had no idea there was a non-stock spec cam in it either, until I started it. So I'm assuming new rings. I don;t know why else they'd have the bottom end out unless just to do bearings.

I need a new compression tester because my old-school style unit is tough to hold tight against the spark plug hole.
Thanks fellas....

Disconnect the ign coil, hold throttle to WOT, and use a compression gauge designed to screw into the spark plug threads.

Lordy! I forgot all about those two person compression checkers. Don't loose it! That's an antique!!

Twenty bucks says it's normal oil vapors and maybe a little blowby. Once you get your breather fitted you won't have to worry about seeing it. If it's mainly doing it once it starts to warm up it's just condensation cooking out of the oil.

If you can't find the right grommet you've probably been grabbing PCV grommets instead of breather grommets. Both have the same size diameter to fit the valve cover hole but the PCV grommet has about a 3/4" inner hole while a breather grommet has about a 1" inner hole. Just about every parts store I've been in has Mr. Gasket 5425 baffled breather grommets on the shelf where they put the engine dress up stuff, header gaskets, etc. Or just look for one over on the little turnstile rack that has a 1" inner diameter.

The cover with the oil filler has a 7/8" ID hole in it for a breather. None of the off-the-shelf grommets are even close. No biggy.... not a show-stopper.
A Mr. Gasket set won't fit. I tried cramming one in and jamming the breather inside but No-Go! Tried a Spectre set too.

Antique?! It's an old Sears unit from the early 80's. Works fine. Presently taking bids!!
;)

It does take a while before it turns to a smoke stack. I'll inspect a little closer when I have it up to temp again.