1988 260 Alpha 1 stuck inlet valves

"Ive just rebuilt my 1988 SB 3

"Ive just rebuilt my 1988 SB 350, which is actually a "260 Mercruiser", dead stock, no mods. Rochester 4 barrel, Flame Arrestor type air filter, Thunderbolt 4 electronic distributor. Its in a in a 23 ft carribean boat.
When I started it recently, it over revved and broke an #7 inlet pushrod. Pulled the inlet manfold and rocker cover off, Inlet valve #7 is locked solid, cant move it. removed valve spring and retainer, used oxy and vice grips to free it. Its not bent. All this black goo came out of valve guide when i applied the heat, looked in all the other inlet ports and its coated everywhere. What is this stuff? Its black, shiny, a little sticky and disolves with WD or petrol. In a valve guide it works like super glue.. I removed all 8 inlet valve springs, stuck same on odd side only. 2,4,6,8 fine free as. (why dont these engines have guide seals?). Valve guide clearence seems same on both sides (each head).
Engine only 50 hrs since reco 2 years ago. Recoed it myself, new rings, bearings, re-use same pistons, hone cylinders by local re-bore shop, Heads recoed by local head shop, inc knurling of valve guides to prevent sticking. (ha).
I think it may be;
1/ crankcase ventilation from each rocker cover goes straight into top of carby, thru flame arrestor, fumes causing black goo?
2/fuel additive i use (Flashlube). its supposed to provide valve lubrication for unleaded fuel in leaded engines.
3/cheap oil i used for running in engine (still in it) causing excessive fumes?
4/Rich mixture from dirty flame arrestor. It was dirty, but clean when i re built engine.

Maybe this goo is normal and I just have to use the boat more often....
Any advice appreciated. Mark."

"3/cheap oil i used for ru

"3/cheap oil i used for running in engine (still in it) causing excessive fumes?"

Why after 50 hours and two years?

"2/fuel additive i use (Flashlube). its supposed to provide valve lubrication for unleaded fuel in leaded engines."

Not needed if it's a Merc. engine; heads have hardened valve seats for use w/unleaded fuel.

The goo may be dissolved sealant you used.

"Ditto what Guy said.

Knurl

"Ditto what Guy said.

Knurling the guides isn't the best way to go - new bronze valve guides are. There should have been seals on your guides. No seals, ancient dirty oil, and a lot of dormant time very likely contributed to your current condition.

Did you winterize the engine each year it sat?

The dirty flame arrester won't richen the mixture any measurable degree."

"yeh dont rib me about the oil

"yeh dont rib me about the oil, ive changed it now, the stuff that came out was thick and black, had to poke sumtin into the drain hole to get it flowing. then i flushed kero thru the sum a few times via the dip stick tube until clean coming out. lotsa big black lumps came out. when I had the sump off a couple of years ago, I modified the drain so every bit of sludge can drain out. (welded the nut onto the outside). downside is the slightest deposit in the bottom of the sump can block the drain hole...
We dont winterise the engine here in sydney, temps 40F to 95F, can use boat right thru winter. My problem is too many family and business distractions keep me away from the boat...
With the flashlube, what thru me was years after I bought the motor, australia changed to unleaded fuel only, I just started using it. Yeh, dumb...
My head guy recommended the knurling, said he does it to all boat donks.
Definitely no valve guide seals in this motor, not now, never was. Only seal is the oring between the collets and retainer.
Inlet manifold sealant i used was Quicksilver Perfect seal. there was a little excess, say one or two runs into each odd side port, but still looked intact, not disolved.. Mark."

Mark:

If you had that much

Mark:

If you had that much s%#& come out of the oil pan I am betting the oil pickup has a glob stuck on it. I would get 2 quarts of "engine cleaner" and put one quart in the oil and run the engine 5 minutes then drain it. The oil you drain will look nasty.

Put in fresh 30 WT oil w/the other quart of engine cleaner and a new filter and repeat the cleaning process again. If your pick up screen gets even a partial blockage while you are running along the coast at 4000 RPMs the engine may sustain serious damage.

"What is engine cleaner? I hav

"What is engine cleaner? I havent seen it down here. Wouldnt the 2 litres of kero i put in the sump have cleaned the pickup? Though I didnt run it with the Kero, A mate told i should have, thats what he used to do with old chevs.. but mines only 50 hours old..Mark downunder."

Engine cleaner is a solvent us

Engine cleaner is a solvent used in the oil just before an oil change if your engine has a varnish/sludge issue. Short trip drivers and/or too long of oil change interval drivers should have it put in the oil before a change.

I've heard of the kerosene method but would only use a quart at a time.