TOPIC: 1962 75hp questions

Ok, good news and bad news on the 75hp and 80hp. The good news is the 80hp compression test is 90 and 95. The bad news is the 75hp has 60 and 50. So i took one of the bypass covers off a 50 cylinder, number 4 actually. The rings are springy, so i'm assuming the others are the same way.

That being said do I bother trying to see if it will run with a hose on the water inlet pipe, (lower unit is off due to a shaft problem PO said)? Or do I have to plan on new rings and some honing?

Since I don't have all the pieces to this motor yet, PO still looking, I was thinking i would do what Professor said and put this power head on the Fat Fifty , kind of an "outboard sleeper". Don't know if the '62 75hp had any better gas milage than the Fat Fifty.

Thoughts anyone?

Bob

Pull the exhaust cover and inspect rings on the " hot side " of the motor.

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My personal opinion on " barn find " and 50 year old motors is that they need to come apart for inspection and repair.

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They usually need some work on seals, gaskets, rings etc.

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Too much work for some it appears , but it is much less frustrating and well worth the effort.

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The 75 will use less fuel , especially if you pull back on the throttle a bit !!.

Professor,
Thanks, I'll pull the cover and look at the hot side. Was looking into powerhead gaskets sets and looks like MarineEngine.com has them for $87 a set, ouch. May have to look and see if I can find them any cheaper, tight budget.

-The 75 will use less fuel , especially if you pull back on the throttle a bit !!./quote] Well that wouldn't be any fun would it?!?!?!

Thanks,
Bob

Many gaskets are now cheaper from BRP.---- Years ago that was not the case.

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Well worth shopping.

You might also check Seirra marine. But you need the numbers to find what you want on there. Or if you have a NAPA parts story they have the Seirra catalog and can find the parts and order them for you. Just check prices first.
Mike aka the pirate

Professor, Thanks looked but the numbers didn't come up. Looks like they only carry 1968 and newer. The gasket group number didn't come up. Did find it on E-bay for around $45, may just get that one.

Mike, Thanks I'll have to look and find the Sierra number. Don't know if they have the whole gasket set like OMC did.

Bob

Many of the 1968 parts such as gaskets may in fact be the same as the 1962 parts ,

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It is worth checking this out !

All you need are the origanl number of the gaskets or any other part you might need to find what you want on the Seirra site. I had the site but some how lost it. Maybe somebody else has it to post.
Mike aka the pirate

Here's the link to Teleflex, the parent company (?) where you can find the Sierra catalog info;
www.teleflexmarine.com/products/engine-and-drive-parts/
Here's another source I'm thinking about trying for O.E. quality parts at a discount, might want to check it out as well;
www.boats.net/parts/search/BRP/JOHNSON/parts.html
(O.E. part numbers, great illustrated parts breakdowns, etc...)

Thanks guys. Looked up the original power head gasket set number and got nothing from either site but did from E-bay. I may just go with the E-bay one. Either that or I'll have to piece it out separately and see if it comes out cheaper overall or not.

Bob

Heres Seirra Marine main page all you need is old or new numbers to find what you need.
www.marineengine.com/
Mike aka the pirate

Last summer I needed a carburetor fuel float for my Evinrude Playmate DU. I typed the OMC/evinrude part number in as a search on E-bay, and also just in Google. I found 2 floats at a reasonable cost. Lots of people have parts listed that they have no idea what they fit, only the part number. SO that is how they list them for sale on the 'net. If you know the part number you want, give this method a try. It is a great way to discover new parts sources as well.

Thanks guys. Well took the exhaust cover off and not good, the rings are springy. Looks like the piston skirts are scored but can't tell real good yet. Going to take all the bypass covers off and get a better look at the cylinders with pictures hopefully.

So question is if they're scored is it worth tearing it all down and hone it and put new rings in it?

Bob

The damage found is no surprise to me !

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It is time to price out all the parts and then decide if your budget allows the fix.

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You might find that piston rings are 4 times $70.00 alone, so that would be near $300.00

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Depending on where you are you might find a good runner for less than that !!!!!

Professor,
Thanks, I'm still going to peak at the cylinders but I was afraid they might be scored bad, I could always hope right? So I guess I refocus my efforts on the '67 80hp. Only problem there is I didn't want to make new holes in the transom to mount this motor since it mounts different than the Fat Fifty. I guess I could just mount that power head on the Fifty lower.

Question regarding the 75 and the 80. What made the 75hp into an 80, just the carb? Were there major mechanical differences between the '62 75hp and the '67 80hp?

Bob

No major mechanical difference

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I could explain it but why ??

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Your best bet would be to go to the

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old omc site

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and read what they said about the 80 HP in 66 model year catalogue ( first year of marketing for the 80 HP )

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We all know that you can believe everything that you read in a brochure.

The 80 had taller exhaust ports. This allowed it to be rated at 5,000 to 5,500 rather than the old 4,000 to 5,000 ratings of the earlier engines. The 1968 85 had CDI ignition & the belt driven disto was replaced by an under flywheel arrangement.

The early 60 - 62 year 75s had skinny con rods - then OMC beefed them up in about 63 or 64.

I bet that if you pull the heads, you find deep scores in the cylinders bleow and above the exhaust ports. The top rings almost always get stuck from coke, and they get "jacked" into the cylinder wall. If you can find a low hours motor without bad cylinders, go that route. A simple hone job won't save a bad cylinder/piston.
OS pistons were available in .010" .020", .030" and .040" In most cases, .030" is the right choice to clean up the jugs. Unless you can find a cheap stash of NOS or good used parts, a set of OS pistons & rings will set you back hunderds of $$ then you have to get a good shop to bore & hone the cylinders. Now you are talking over a grand to do that engine, and that's you doing the teardown and assembly.

I've probably torn down 15 or so 60s vintage v4 engines to sift out good parts. Sometimes you will find a good piston or two - set it aside for other projects.

Thanks Bruce. Got side tracked with honey do's today but I'll pull the heads and double check just to make sure.
Pulled the heads and this is what I found:
#1 intake side


#3 intake side

#2 exhaust side

#4 exhaust side

#4 piston


Guess it's time to focus on the 80hp.

Bob

No 2 has had water sitting in it. The scores on the piston skirt (exhaust side) are typical from what I have seen on motors with a lot of hours. That engine looks to have been used a lot, there is no remaining hone cross hatch, those bores are well glazed and galled. Just keep picking these up for real cheap ( like 50 bucks) and you will glean anough good pistons and a block that can be honed out. They are out there. Especially look for an engine that had a replacement power head from OMC. These are usually still primer red - that is the only color they were shipped in. The welch plug on the block water jacket will be stamped "RPH" with nothing else. These powerheads were NEW not rebuilt. I've found 2 of them in my search. Both were only lightly used and in great shape.

These engines were damaged by people using crappy motor oil, too much oil in the mix, and allowing the motor to lug. Use good quality TCW3 oil at 50:1, prop the engine so it will turn 4,500 - 5,500 at WOT with a light load. The rings will stay much more clean that way.

Thanks Bruce. I should have know something was up when I saw the heads were not original. One was primer red and the other had some silver paint over the primer red. Seems like the PO beat it up pretty good. I'll refocus on the 80hp since it at least has 95 across all the cylinders. I am having problems with the exhaust cover. Majority of the bolts broke and it won't pop off right now. Verrrrry corroded when the bolts broke off. Not a good sign externally anyway.

Bob