DansYellow66

Not a Corvette but sort of relates to the C1 cars.

My ERA 427 Cobra has a nice, not too rowdy, custom stroked 428 Keith Craft-built engine with very few miles and no signs of any issues. I never thought a 4.25 in stroke could run so smooth and rev like it does. I don't have PCV but I have a breather oil fill cap at front of the 427 intake and a manifold breather at the back of the manifold - no road draft tube. Nothing on the valve covers.

I get the usual stench of a couple drops of gas dripping out of my rear carb shooter on to hot throttle plates after about 10 minutes heat soak after shut off. I've done about all I can for that with carb heat shields and insulator gaskets. Very distinct odor - all my old car occasionally experience it.

But, I've noticed when warmed up and pulling up to a stop light or when pulling into my driveway and stopping, I get a real acrid exhaust odor that waffles over the top of the door for a bit. But I don't think it's from the exhaust which are my car are underneath and out past the rear bumper. I'm guessing it's happening when my radiator fan has kicked on. Seems odd as there is no sign of issue with the motor and then it dawned on me - are these crankcase fumes I'm smelling that are circulating out of the engine breathers and getting blown underneath and out the side louvers when the fan kicks in? This is while I'm driving so it's definitely not gas boiling off anywhere which has a different odor. Anyone else with a non-PCV car noticed something like this with a hot engine in slow or stopped traffic? Sound like what's happening? I've been around awhile and have or have had several 60s era cars but they all have had PCV except for this one.

Thanks

kellsdad

Dan,
I sold my Cobra replica last year, but I drove it frequently for about fifteen years before that. Mine had a 408 Windsor without PCV. The valve covers were vented via large hoses to a vented catch-can. I don't recall any odors like you describe, but that car was such an overwhelming sensory experience that I might have overlooked it. ... As your engine has "very few miles," I'm wondering if you are smelling something that is burning off like paint on a hot engine part, or something a bit too close to the exhaust system. If you stop aggressively, it could even be something from the brakes.

MikeM

Sounds right to me.

GTOguy

A PCV system will increase horsepower, lengthen engine life, and prevent oil leaks. There is no downside to running a PCV system.....there is a downside to not running one. Not telling you what to do with your car, just making a statement.

DansYellow66

I haven't anything against PCV systems - it's just going to take some effort to adapt one to this engine. It's basically set up as a 63 427 engine and I'm not sure they had PCV. My carbs are run of the mill 1850 and they do have a fitting that could probably be used but I'm not sure of the size.



But my primary carb is up front (backward mounted per Ford) and it's pretty tight there. I would have to come up with some sort of pcv adaptor off of the rear manifold breather opening.



You can see the round chrome top breather at the rear in this photo.



Not sure the occasional odor is enough of an issue to go through all the trouble. Just sort of wanting to confirm that that's probably what it is - crankcase fumes.

kellsdad

What oil is in it?

DansYellow66

Joe Gibbs 20W-50 conventional per the builder.

Frankie the Fink

I can't distinguish 'acrid' from 'sickly sweet' -- which is the smell you get with a too rich fuel mixture. Now, crankcase odors can be a bit pungent.

With a road draft tube and with the car stopped, you're not really 'scavenging' the crankcase vapors as there is no air flowing across the road draft tube 'snout' to create the pressure needed. So vapors and even liquid fuel can be produced from the tube... (A PCV system is active at an idle - another advantage)...

I'm not sure how to check that and I'm not convinced its something to worry about anyway.

If smells electrical that's a different story - I'd start digging around before driving anywhere...

DansYellow66

Pungent might be a better description Frankie. Pulled off the breather today and took a wiff of it and it seemed similar. It was clean as could be though. Took a look at the engine today and it would be a major effort to put a PCV system on it. The primary carb fitting ends about a finger's width from the throttle cross-over rod and is dead level with it so hooking any kind of hose to it would foul my throttle linkage. The manifold hasn't any provision for PCV at the carb base and the little S&H filters don't have a big enough base to attach a fitting for a hose. My interest was just understanding what the occasional odor is. I can live with it.