318 diagnosis
i thought you were on to something with the PCV. There was some oil on the valve and at end of hose at carb which goes into the center port on my 1406 Edelbrock. I disconnected the valve and ran it out on the highway with no change. Still leaving a decent cloud on hard excel.
I missed that
But-um, if your mufflers do not have drain-holes, and they have an accumulation of oil, from an over-active PCV system condensing in there, then the mufflers have to get pretty hot to burn it out.
Here's a simple test;
flip the PCV out of the valve cover, and seal both of the valve covers, and then put a pressure gauge on the dipstick-tube. Start her up and let her idle.
1) There should NOT be any vacuum in the CC. If there is, then the only place it can come from is the intake to head gasket.
2) at idle, the Whiplash cam does not make a lot of vacuum, so then, you may have to idle it up, to say 1400 ish rpm. But if you do that, watch for pressure, which is what should be happening, and if it does, then, immediately idle her back down.
3) the pressure should be slowly and steadily building up. Do not let it it climb up past 3 or 4 psi, else it can blow seals or gaskets out.
4) if pressure builds up fast, and if you can see your gauge needle pulsing, STOP the engine! The pulsing is a gouge in one of the cylinders.
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I had a single-cylinder dirt-bike come in once that did this, and what had happened is that one of the wrist pin clips, not a spiral-loc, had popped out and the wrist pin had slipped over to one side and was rubbing on the cylinder wall. Whenever the rings passed over the gouge, on the compression stroke, some of the pressure would scoot thru the gouge and end up in the CC. It was also somewhat hard to start, and blew smoke.
How I found this before teardown was by using the LD tester, set to low pressure, and with the valve lash backed off, and then slowly manually turning the engine over with a breaker bar, stopping every few degrees to let the pressure stabilize.
At the very top, the LD was minimal, but as the piston dropped and the rings exposed the groove, the LD changed. Hmmmmmm I said to myself, that's not normal............. The cylinder was beyond repair.
BTW,
after the repair, it still blew smoke ..... until the muffler cooked the oil out of itself. Scary moment? No, I knew it would happen, and advised the customer.
BTW-2
at WOT,
the manifold vacuum is getting close to zero. If your engine is smoking Blue at WOT, it is NOT likely from a vacuum leak into the CC, nor from valve seals.
In order of likelyhood the engine is burning oil that has entered the combustion chamber from;
1) the PCV system, or
2) fuel-wash from a very rich carb
3) a faulty intake to head seal, in the valley, or
4) oil Not being scraped off by the Oil-control rings, or
5) too much oil in the CC, or
6) just oil having accumulated in the mufflers/exhaust system, or
7) a problem in the cylinder walls, or
8) fuel-contamination
BTW-3
Smoke on hard decel is a bit of a different problem.
In this case the engine is creating all the vacuum that it can, in the chambers, and the usual entry point of oil is past the valve seals, but also includes the PCV system which enters the intake below the now-closed throttles; AND the valley seal, and in the case of the Whiplash, the headers are gonna try and evacuate the plenum on the overlap cycle.
If your throttles are also sitting very low on the Transfer slots, this will aggravate the entire situation. ( your Transfer slots exposure under the throttles should be square to ever so slightly taller than wide.)
However, In this case, under high vacuum/low rpm, the engine is Not processing much air so not much exhaust. The exhaust gasses are cool, and so is the exhaust system, and the oil easily condenses and accumulates inside the mufflers. Over time, it will also begin to coat the very ends of the tailpipes, where you can swab it out.
In a normal-running engine the only things coming out the TPs are hot air and water; Not soot, Not oil, Not any glazing. If anything, there might be a whitish to tan baked on finish, impossible to swab out, same as may appear on your sparkplug porcelains.