Hi all, asking for a friend of mine. He has an 86 style 350 TPI Chevy engine.

It seems to run great, plugs all come out picture perfect, does not really use that much oil, and does not blow any smoke out the exhaust but it's really fumy out of the oil cap and breather. Like really bad fumy, it can be stone cold then you start it up and it's puffing away, it tends to settle down a little, but if you give it a good rev then it gets really bad again. Oil pressure seems pretty steady, about 40, bit more when cold.

I would of thought that if the engine was warn or there was problem it would blow blue smoke out the back and also oil up the plugs, but it runs fine, just is really fumy from the top of the engine.

Whats going on there?

Excessive blowby from worn-out rings.

I thought that, but the clean plugs and clean exhaust still throws me off. Most the engines I've seen do that have oiled the plugs and blown smoke.

Not that it matters, but out of interest. He has only ever used M1 15w 50 and it's only got about 120,000 mile.

PCV system?

replace the valve seals

if its an 86 with the original motor than you have a 305 Tpi

Yes Sorry you are right. It's had an Isky Cam installed and really hammers, so you just assume it's a 350.

NO PVC system, all gone.

Do you think just the Valve seals might be all thats wrong?

That's part of your problem.

But wouldn't the issue of it being really fumy still be an issue?

Hook up the pcv - mine is just like this, if the pcv is disconnected I get a nice wispy smoke screen up the windscreen at traffic lights, but otherwise blows no smoke from exhaust. Every motor has some degree of blow-by, its gotta come out somewhere, might has well have pcv deal with it as its supposed to.

So does this mean that there may not really be an engine issue?

I was going to look at running a heaver oil, but was not really wanting to.

the PCV system does help to keep the inside of the motor cleaner, which helps the oil last longer & in turn helps the motor last longer.
PVC is not an really emissions part, it uses no power. any motor that is going to see street use should have one.
if your lucky, the motor is ok.