Older Inboard Engines

[JonS]

I read this last week about this. If an engine was designed to run on leaded fuel, after a few years of it running on leaded fuel, the seats and valves have been coated and will be protected for up to 10000 miles (in a car). But, if you have the chance to put in a bottle of lead substitute every 5 tanks of gas, this would not hurt. If it were mine, i would run unleaded with a lead substitute every once and a while, if when needed, have the heads redone with hardened seats. I am not sure if a higher octane gas would help. I am trying to research this for myself also.
I would upgrade the old points and cap with the new electronic ones for around $100.

 

[james1]

Thanks Jon.

I did find one old paper on the web that recommended using a top end lube like Marvel's Mystery Oil in the gas to make up for no lead. It looks like the paper was written right at the time of the change to unleaded gas. However, the top end lube wouldn't help with lower octane. Your info is very helpful!

 

[terminaldegree]

I worked at a marina that had MANY antique powerboats, some with original engines, some repowered. We ran most of the original engines on 89 octane unleaded and a small measured cap of an additive for engines designed to run on leaded gas. I think the stuff was made by Stuart-Warner.

With something that old, it may or may not have been rebuilt once already, with varying degrees of expertise. Exhaust manifolds and risers will need to be checked for leaks, as they can trash an engine in a hurry. Other than that, the usual gamut of stuff: compression check, run the engine under load to see if the carburetor is adjusted properly, see if it makes the original full-throttle rpm. What specifically are you looking for/at, boatwise? Don't forget to check the transmission fluid, shafts, struts, rudders, etc.

 

[james1]

Hello,

I am looking into buying late 60's inboard. My question regards the use of leaded fuel. I spoke to one classic boat salesman and he indicated I could run any modern gas with no problems. I still have reservations though. Am I worrying for nothing? Also, if anyone has any advice on what to look for in a '69 - '74 inboard, please sound off.

Thanks!

 

[JonS]

I have not heard of any older inboards with transmission trouble. Most old boats engine/trannys die from internal rust and corrosion from either little use or water entering thru the exhaust or poor/old fuel with water in it.

 

[BUBBA0420]

James: Go with the Marevel Marvel Mystery Oil
for sure also Valvetect makes a Lead replacement
additive. If you want actual Tetra Ethly Lead you
can buy it from www.batterystuff.com and use
at least an 89 octane gas. As far as the trannys
on inboards they pretty bullet proof. By the way
all lead replacement additives are not created equal

 

[terminaldegree]

OOH, old Century's... One of my favorites [never owned one, had friends who did].
Resorter or Coronado, I assume?
The direct drives transmissions are usually long-lived. The most common cause of death I saw were ones that had a leak, and the owners didn't keep up with it or do repairs soon enough. What's it have for an engine, Ford 352, Chrysler v8?

With something this old, I would look REALLY closely at the stringers and engine mounts in addition to the other things I talked about. Usually you're looking at fiberglass wrapped wood for stringers, and often the wood is totally rotten, leaving a weak shell to support the motor and transmission.

The old style "aircraft" throttles were neat, and would occasionally hang up. I loved the car-style shift lever [assuming it has one], but sometimes it would slip out of "forward" in chop. These are lovely old boats that were really fun to drive and to listen to.

p.s. since you're used to outboards, know that water pump impellers are yearly replacement items. Don't forget or you may overheat!

 

[james1]

Terminal,

I am leaning toward the Resorter because of funding and boat lift limitations (also funding related). Plus, if I got a Coronado now, what would I aspire to? I have been mesmerized by these boats ever since seeing them as a boy. I keep telling my wife, "Wait until you hear one, you will be hooked!"

I am looking at about 3 boats and two I think are Fords (Interceptors) and one is a Chrysler. They all have the aircraft throttles and the shift lever on the tree. The stringer thing is what has me most worried as I'm not sure how to tell good from bad except sort of gague from the look of the engine compartment. Thanks for the heads up about the impellers.

Since this is an Oil related message board I should mention that I plan on doing an AutoRx treatment and then run a HDEO 15W-40. I run all synthetics in my cars, but I would be afraid of 40 year-old seals etc.

 

[terminaldegree]

One trick regarding the shifter--

I was looking at an early 70's Resorter once, and the owner actually reversed the shifter, so that down was forward. It stayed in position better over severe chop.

The stringers is just a matter of opening up access points, and looking and poking around a little with a screwdriver. The engine mount is the largest point of stress on the stringer system. Some old boats you look at [bring wrenches], you could move mounting bolts around by hand, or with no resistance on the wrench. Others you could press a screwdriver into the fiberglass and it was just thin and brittle, as the wood underneath had just wasted away.

I don't mean to scare you, I'm just saying to be careful as at least one of these boats [if not more] will probably have this problem. Also check for damage to the transom [I think it may be wood cored-- bad news if water gets in]. The bottoms were solid glass if I recall.

We once pulled up 5 waterskiiers at once behind a mid 80's resorter with a 350 chevy. It's a nice boat for a small group of people and calm water.

 

[james1]

Thanks for the info.

I am specifically looking looking at Century inboards. There is a '69 in particular that I have come across. I don't believe the engine has been rebuilt. It has had one owner and I believe has seen little use the last few years. I grew up with outboards so I have a pretty steep learning curve for these inboards. Do these direct drive boats have much in the way of transmission trouble?