Overheating heads? Blistered paint on cover casting.

[cheburashka]

Had my '57 Lark out for the first time. It runs very well for a fifty-year-old. There's plenty of water coming out of the back when it runs, and the cooling system looks to be working just fine. <br />After a couple of runs at WOT, I shut it down and looked under the shroud, and everything seemed to be in order. No smoke, no ticking noises or other signs of overheating. Later, when I was going over it more carefully, I noticed that the two cover castings that stick out above the spark plugs were discolored and that the paint was beginning to flake off. The rest of the cylinder head looks fine. Is this something I should be concerned about? The only thing I can think of that would cause that kind of overheating would be excess timing advance, and I checked the linkage that goes from the coil plate to the carb and it's set up exactly as the manual says. Am I just being paranoid?<br /><br />Thanks,<br /><br />Steve

 

[Goodoleboy]

Re: Overheating heads? Blistered paint on cover casting.

Could just be a poor quality paint and or paint application.<br /><br />If you want to be sure your not overheating. I would recomend you get the temp. melt sticks from auto. parts store.<br /><br />Head should not run above 175 or below 125. Buy sticks accordingly.<br /><br />Apply to marks on head and watch for melt. 125 should melt and the 175 should not.<br /><br />If it passes this test then I would call it good to go.<br /><br />Good luck!

 

[R.Johnson]

Re: Overheating heads? Blistered paint on cover casting.

Does that engine have the compression relief valves in the head? Check the control arm coming from the rewind starter, and see if they are being held open, or take the head off, and see if they are stuck open.

 

[Paul Moir]

Re: Overheating heads? Blistered paint on cover casting.

Does your Lark have the linkage between the pull-starter and the head for compression relief? If so, the linkage may have gotten stuck and caused the compression relief valves to leak exhaust gasses, which are very hot.<br /><br />EDIT: R.Johnson beat me to it!

 

[cheburashka]

Re: Overheating heads? Blistered paint on cover casting.

I'll check the compression relief valves. Sounds like a likely culprit.<br /><br />This might be a dumb question, but what is the purpose of those castings that stick up above the spark plugs?

 

[Paul Moir]

Re: Overheating heads? Blistered paint on cover casting.

Beneath them is where the compression relief valves lay. If they weren't there, blazing hot exhaust gasses would otherwise shoot straight out the back of the engine during startup, which would be very dangerous.<br /><br />Your post reminded me of this:<br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=28;t=015607#000000

 

[vzal]

Re: Overheating heads? Blistered paint on cover casting.

Hello, Cheburashka!<br />Greetings from Crocodil Gena

 

[cheburashka]

Re: Overheating heads? Blistered paint on cover casting.

Two direct hits!! The rockers weren't off by much, but they were definitely tighter than they needed to be, and I'm sure that the hotter the engine got, the bigger the leak got. The problem was bad enough that I had to readjust the carb once I had loosened the valves. You guys know your stuff!!<br /><br />Hello Gena. Doesn't your accordian get wet in a boat?

 

[vzal]

Re: Overheating heads? Blistered paint on cover casting.

Ah, not really when not moving.<br />It seems you are rather advanced in mechanics. Would you please look at my postings and see if you might give me an advise.<br />Thanks you

 

[cheburashka]

Re: Overheating heads? Blistered paint on cover casting.

I can't hold a candle to the regulars on this board. Points, condenser and magneto is a complex enough system for me , and even there I have to rely on folks here to set me straight. Yours must have electronic ignition and probably computer management. I wish I could help you, but I don't know much about antique outboards yet, and I know nothing about new ones. <br /><br />Is there a computer diagnostic program for the newer motors? I know I couldn't do anything on my '97 Audi without a computer diagnostic system. <br /><br />Good luck to you!

 

[vzal]

Re: Overheating heads? Blistered paint on cover casting.

No computers but e-ignition and 6 carbs. What I can not figure out is how to spark test while acting up.<br />Thanks anyway, hope for a good luck next summer.