1974 mercruiser 165 getting replaced by 1978 mercruiser 470

[Rinker captiva 206]

I am planning on replacing the whole powertrain in a 1974 22 foot cuddy. The boat originally had a 1974 Mercruiser 165 with the older style MC-1 drive.(without trim pucks on the side of gimbal ring). I have a junk boat with a 1978 Mercruiser 470 that I would like to swap in.(It has the trim pucks on the side of the gimbal ring and I would like to use the newer style MC-1 drive. I have read that in order to make the 1978 fit the 1974, the top bolt holes must be moved. Do all the other holes line up? How do I patch up the old holes? Is there anything else I should be aware of?

 

[GA_Boater]

Curious - What's wrong with your inline 6? Overall it's a better motor with more parts support than a 470.

 

[Bondo]

Do all the other holes line up? How do I patch up the old holes? Is there anything else I should be aware of?

Ayuh,..... Welcome Aboard,.... Ya the other holes line up,...

The old holes are inside the dry area, do nothin' if you wish, or fill 'em with putty or resin, or,....

The 470 is probably the worst choice possible,...

 

[Rinker captiva 206]

Here is the whole story. We actually got the boat for free. The engine was bad. It had a chevy 250 out of an old truck. We had an inline 194 out of an old nova(that was sitting for many years) that we put in it. We were never able to get that engine to run correctly, due to it having a cracked cylinder wall. The car is getting a V8 so we thought we could get away with using a free motor. (the inline 6 194). Finally got tired of screwing with that so I pulled it last fall. We found a boat with rotten hull with a 470 for cheap. we ran the 470 in the boat it is in. Runs like a champ. The voltage regulator even works! imagine that. It will be getting an alternator anyway. but I have a 470 in my 79 aristocraft. I really like the engine. Great HP for 4 cylinders!

 

[Rinker captiva 206]

One other thing to mention, I have an extra 470 that I picked up from an estate sale, along with a 140 for $25.00. So i have extra parts for that motor.

 

[Bondo]

Ayuh,.... It's a straight forward swap, just the 2 bolt holes,...

superfets is lookin' for a 140hp,...
The drive on the Chevy in-line will have a shorter input shaft I believe,....

 

[QBhoy]

For the love of God why ?
It'll be the quickest route known to misery, despair and ruined family days out.

 

[stonyloam]

I don't think it is such a bad idea. Already runs a 470, so going in with eyes wide open. BTW in the 25 years I have owned my 470 it has never failed to get me home.

 

[Rinker captiva 206]

I don't think it is such a bad idea. Already runs a 470, so going in with eyes wide open. BTW in the 25 years I have owned my 470 it has never failed to get me home.

That's what I like to hear! Looking around other threads on this forum, people like them or hate them. Thanks for the support.

 

[achris]

...The drive on the Chevy in-line will have a shorter input shaft I believe,....

Sorry, the short yoke was used on ALL in-lines to 1982, so he'll use the same yoke from the 165 to the 470...

For the love of God why ?
It'll be the quickest route known to misery, despair and ruined family days out.

Uninformed, 'band-wagon' comment. The 470 is, in essence, a nice engine. Yes it has some issues, but mostly they are well and truly worked out these days. Someone who already has a 470 is in a great place for a project like this.

I don't think it is such a bad idea. Already runs a 470, so going in with eyes wide open. BTW in the 25 years I have owned my 470 it has never failed to get me home.

Agreed....

Chris........

 

[QBhoy]

Acchris
I admire guys with the patience for these engines...no doubt.
But...for your average joe (my friend, whom has no patience and 3 kids) I find it hard to agree.
He has had 2 engines rebuilt after the usual over heating issues....even after having the mechanical drive seals re done.
When she was running...man, no argument over the power...what a machine.
We ended up putting a 3.0 in her. She is a fair bit down on power, but so much more reliable now.
Thought about the 4.3, but the mountings had to be changed and likely the drive too.
Long story short, she has lost about 2 mph and perhaps a little low down hole shot. Otherwise, it was the right thing to do.

 

[QBhoy]

Achris
Totally understand you having faith in these engines and also thinking I was just making a genetic comment on the matter.
I'm one of the few who actually have a bit of mechanical experience (and misery) on the subject.
I totally respect the ability of these engines...just that I've also been witness to their low points too.
It's really put my friend's wife off the thought off and reliable boating with their family is now a subject of eventual trust. Now the 3.0 is up and running, the lack of power is a small price to pay for the rejuvenation of trust and get-you-home ability.
I'm sure you know what I mean ? Having to tow him home with my own boat every other time wasn't much fun, previously.
All the best.

 

[QBhoy]

Should read "generic" and "of"...not genetic and off

 

[stonyloam]

Q, you might be a bit over propped with the 3.0 if you are using the original drive. The 3.0 outdrive has a lower gear ratio than the 470. The 4.3 and 470 use the same gear ratio so no need to change the outdrive. You might improve the performance with a little lower pitch or smaller diameter prop.

 

[QBhoy]

Thanks Stonyloam.

I've only been on the boat a few times since. It is a bit slower out the hole, but not terrible. Top end is only about a few mph down. From memory it ran about 4500 rpm with the 3.0 wot.
You're right, he may be able to go down and inch or two. The prop isn't in good shape, so may be throwing the readings. He is actually looking into it now. Thinking of a stainless.

 

[stonyloam]

Yeah WOT on a 3.0 can go up to about 4800, so you could probably go down an inch in pitch to gain about 200 rpm and still be OK. Top end speed may actually go down a bit but your hole shot should be improved. Good luck.

 

[Rinker captiva 206]

Yeah WOT on a 3.0 can go up to about 4800, so you could probably go down an inch in pitch to gain about 200 rpm and still be OK. Top end speed may actually go down a bit but your hole shot should be improved. Good luck.

How big is your boat and what does it weigh?