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Old 03-27-2023, 11:00 AM   #1
Kudzupatch
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283 out of long term storage

I have a 283 out of a boat. It was running perfect when the boat hull developed some issues. It has not been run in 15+ years.

Got it on a stand and running compression checks and it is horrible on most cylinders. Pressure is all over the map.

Like 30 lbs on the worst with about 50-60 on several. One good cylinder. Obviously it didn't run in that condition so storage has taken a toll on it.

Checked a couple of cylinders with some oil in them and maybe 5 lb increase. So I reading this as the rings are fine and I probably have issues with the heads not sealing. Make sense?
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Old 03-27-2023, 11:35 AM   #2
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Re: 283 out of long term storage

Needs a valve job.

This motor was built before lead was banded in fuel. Unless the valves were replaced the valve stems are dead soft compared to modern valves. It is east to tell, a file will put a flat spot on them. Replacement valves all have stellite hard face on the stems. A file will go over the stems like they were made of glass. If the boat engine has been ran much on lead free fuel the guides will be undersize. Plan on replacing all the valves. Most will tell you to replace the seats with inserts. I personally don't think it's that important unless you plan on putting 10k miles on the truck each year.
Good luck on your project.

Last edited by Accelo; 03-27-2023 at 12:01 PM.
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Old 03-27-2023, 01:20 PM   #3
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Re: 283 out of long term storage

Heads are where I leaning too. I am thinking the valves are not sealing for some reason. Being stored so long I am not surprised.

I should mention it is going back in the boat. Just spent a few years restoring it. Last thing is the engine. It ran perfect for years. No issues, no oil use and rather low hours too. It is a 1963 so the engine is older for sure.

I have never checked the number but Chris Craft says these were the industrial engines that were converted to marine use. I have heard it said that they use a (?)high nickle block, same as the Corvette. Not that it matters but would be interesting to know though.

I believe the heads are old enough they have o-rings instead of seals on the valves? Looks like it but will have to tear it down and see. While I have it apart it is a good time to upgrade the valves. I plan on using a lead additive as well as zinc. They used a solid lifter cam too.
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Old 03-27-2023, 01:36 PM   #4
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Re: 283 out of long term storage

I bet the ports, valves, and seats are rusty. Possibly the cylinder walls too.

This was the last "running when parked" boat motor I tore down.






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Old 03-27-2023, 08:06 PM   #5
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Re: 283 out of long term storage

Yup, even the moist air in cold storage will rust the cylinders. Sometimes you can get lucky if an engine sits in a vehicle that still has a hood with the air cleaner intact.
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Old 03-28-2023, 11:19 AM   #6
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Re: 283 out of long term storage

Wow, that compression is low. What I've heard so far makes sense. If it's rings, oil would help. If it's valves, oil won't make much of a change. Hopefully it was stored without any water in the coolant system, or at least with antifreeze.
A professional valve job by a reputable machine shop would be best, but also the most expensive.
It sounds like you're handy, so you can do small incremental stuff and test it and see what works and get by with the minimum work. You might get away with as little as valve lapping. Grinding paste and one of those double ended suction cup valve lapping tools. Or just do it once, do it right, and have the machinist do the valve job. Lots of good options.
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Old 03-28-2023, 11:49 AM   #7
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Re: 283 out of long term storage

Once I stored a 327 for almost 25years. I had it rebuild and never started it. I did pull the heads to confirm everything was ok inside. It was always inside without water or oil. The good news is I never adjusted the valves so the cylinders were sealed. I wiped the cylinder walls with some ATF and re-installed the heads. Ran fine and is still running.
It all depends on storage conditions.
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Old 03-28-2023, 01:39 PM   #8
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Re: 283 out of long term storage

Lead era heads in need of work...I'd jus throw a set of new modern heads on myself.
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Old 03-28-2023, 02:00 PM   #9
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Re: 283 out of long term storage

Quote:
Originally Posted by mattfranklin View Post
Wow, that compression is low. What I've heard so far makes sense. If it's rings, oil would help. If it's valves, oil won't make much of a change. .......
Tried oil and saw only 3-5 lbs difference. Small enough I knew it was not rings and sort confirmed what I was was thinking. Just never run into this before. They were just usually worn out but this engine is pretty low mileage/hours.

Got in on the stand and manifolds off. Looks good so far. Heads off soon. Depending on what I find I will decide what to do. But if it looks good I may just lap them. I have no issue with using a lead additive. Got to do zinc in the oil so no big deal.

Taking it apart will sure make it easier to clean and paint!

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Old 03-29-2023, 08:33 PM   #10
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Re: 283 out of long term storage

.

Nice looking boat.

-klb
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