Howdy from Texas, The head gasket on my original 346 Flatty (48 Cad Club Coupe) is apparently allowing oil to be sucked into the pistons causing smoke and hard starting. My question is ..since I am going to pull the heads to replace the gaskets .. what else could I do while I am in there as general maintenance and/or performance upgrades ? I have seen some pics from fiftyV8 that show the lefthand crossover exhaust had been removed to create a true dual exhaust ? Any other maintenance /performance suggestions appreciated. Thanks
I don't know about Cadillac flatheads, but Ford flatheads have no oil in the heads and no way for a head gasket to allow oil into the combustion chambers. How are Cads different?
Well, I honestly dont know. I am getting oil in my cylinders causing smoke. I also am getting oil and water thru the blow by tube but there is no water in the oil .. The dip stick is clean of the classic white sludge associated with a blown head gasket. I assumed that the gasket had failed next to the piston and valves allowing the oil to be sucked into the cylinder rather then failing between the oil and water jacket allowing coolant into the oil. I could be wrong.. I had one middle head bolt on the left side leaking oil. I tightened it to 70-75 ft lb's. But I feel the damage has already been done. I want to add that this is my First Fathead .. So my diagnostic skills are very limited since I have always had 1952 and newer Caddies.
OK, so I think you first need to figure out whether there are oil passages in the heads. There probably are none, because there's nothing to use oil up there. The oil has to be passing through the rings to get into the combustion chambers, which also means your head gaskets aren't the problem, but regretfully you may have a bigger problem. Water in the blow by tube may be condensation from the crankcase. Or if coolant is leaking into the cylinders from the head gasket, you'd have steam (looks like smoke) coming out the exhaust. One way to check for coolant leaks is to drain the oil and see what comes out first (coolant sinks to the bottom of the oil pan).
yup, sounds like a ring problem. You might want to do a compression test, it's the first step in diagnosing engine problems.
Just another thought, worn out valve guides may allow some oil to be sucked in on the intake side, but I don't think it would be much because it would have to defy gravity.
When I bought my Flathead,,,,#1 intake valve had lost its horseshoe off the valve guide. Looked like it had been that way for a while ,,,the guide was worn very bad from bouncing up and down . It also had drawn oil into the chamber ,,,from the vacuum created by the piston,,,,entire chamber and valves were coated with oil from the tappet chamber . I was gonna post earlier,,,but I wasn’t sure about a Cadillac Flathead . I didn’t think they had any oil above the head,,,,,but,,,,I only have a little experience with a Mercury,,,,,I didn’t want to speak out of turn . It sounds like the caddy is using oil ,,,,,or ,,,it is leaking antifreeze into the chamber . I can’t imagine oil leaking from a head bolt,,,,it must be something else . Tommy
Yes, it is a 48 Flat head (346) there is a row of head bolts down the middle of the head. The 2nd one from the front on the left side was leaking oil.
I am a little late to this party and it seems most thoughts have been aired. I am not sure that I can add anything right now except to say, be sure not to over fill your engine oil level as that could possibly force oil vapour to be pressurised, but not sure where it would come out without seeing detail engine pic's to know what has been done to your engine. IMHO going back to your original question regarding improvements. probably consider improving spark (HEI dizzy), exhaust out (twin pipes) and fuel in (multi carbs). No different to dealing with any other mild engine improvements. Other improver is to lose engine weight I guess. Generator to alternator and mini starter motor for starters pardon the pun...
Dual exhaust on one of these is a bit more challenging that most engines, since the exhaust comes out the top of the engine. I wouldn't get too carried away with trying to modify stuff, until you have good understanding of how it works as designed, and you can get it to work as designed. Don't get too far ahead of yourself.
The exhaust I saw and thought would be doable was on a 346 that used the factory left side exhaust manifold exit port and eliminated the crossover from the right side and ran the right exhaust pipe from the crossover port on the right side manifold.
Most things can be achieved with time, money, skill and motivation. Compression test would be a good first start point. Decisions from then on can be based on the results you get...
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