Engine swap advice needed.........

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mrcj001

Petty Officer 1st Class
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Jul 25, 2008
Messages
313
As some of you know, I need to replace my engine. I found a 1977 Evenrude 70 HP. which is rated for my boat. Havent got it yet , just want to get advice befor I do this. The replacement engine DOES NOT HAVE THE TILT & TRIM.
The 135 that is on there is to big anyway for the boat.

I`m going to look at the new engine tomorrow.

What is a good compression reading on this motor?

Can you guys look at these pics and tell me what I`m in for and if I could still use the trim unit that is on the boat now? The engine in the pics is being replaced.

also, does the 1976-1978 70 hp have "electric shift"?

Any special tools?



080-1.jpg




082-1.jpg



081.jpg
 
B

BigB9000

Lieutenant Junior Grade
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Dec 5, 2007
Messages
1,154
Re: Engine swap advice needed.........

Trim unit is possible....

IF you like drilling holes into your steering/transom bracket.
AND you have the knowledge to remove and reinstall the bracket.
Mounts and screws may break during the disassembley. The steering tube would be the hardest part to remove.

But, thats only if you have the clearance between the bracket and the exhaust housing on the 70hp to install that lifting plate.
 
B

BigB9000

Lieutenant Junior Grade
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Messages
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Re: Engine swap advice needed.........

I would just pull the unit off myself. Although, I can deal without PT&T.

Interesting design though.

It looks like its more of a Power Tilt unit than a trim. The angle for the hydraulic cylinder doesn't seem to be ideal for pushing a boat.
And I would never trust that attached plate.

Also, your straps could be better. I recommend a ratcheting type, and 1 1/2" thick.
 
1

1kruzer1

Petty Officer 2nd Class
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Apr 26, 2008
Messages
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Re: Engine swap advice needed.........

70HP from 1976 on are mechanical shift. I have 130 PSI compression on my 1976 on all 3 cylinders, but that's MY guage under MY conditions. Even compression between all 3 cylinders over 100 PSI is what you are looking for, rather than exact numbers. If maintained and in good shape, these are good engines. Realize that you are cutting your horsepower in half, and may have to re-prop any used engine you find to match the boat. What HP is the boat rated for?
 
M

mrcj001

Petty Officer 1st Class
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Re: Engine swap advice needed.........

The boat is rated at 70 hp max.
 
E

ezeke

Supreme Mariner
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Sep 19, 2003
Messages
12,532
Re: Engine swap advice needed.........

The PT&T unit will transfer with little modification. I don't see why the power lift unit would not transfer just as well. If it has them, you would need to switch out the tilt assist cylinders for regular shocks on the 70.

The only problem that I see is that the PT&T pump is of a kind that is difficult to replace and service.
 
M

mrcj001

Petty Officer 1st Class
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Messages
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Re: Engine swap advice needed.........

Well, purchased a 1976 Eninrude 70 hp. Gave him 650$

All 3 cylinders were at 122-125 lbs of compression.

Engine started and behaved like a outboard should. The old man said it did have low hours on it. His transom on his boat was toast.

Ezeke, I think you are correct. I does appear that it will bolt up to the trim unit.

That tilt motor went bad on me before, the overload curcuit was tripping. I had the circuit by-passed and fused the motor at the battery. It seems to work fine. It picks up the boat anchor I have on it now. The 70 rude it light to be compared.

Heres a pick of the nnew motor:

001-2.jpg



Also it looks like he dinged the prop, does this look real bad?

002-3.jpg



003-2.jpg
 
E

ezeke

Supreme Mariner
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Sep 19, 2003
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12,532
Re: Engine swap advice needed.........

The stern bracket looks good.

What pitch is the propeller? Looks like it was in the sand. A prop shop could dress that up and balance it if the price were right.
 
M

mrcj001

Petty Officer 1st Class
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Re: Engine swap advice needed.........

I looked at the model number on the stern bracket and it is (65273S).

this seem s to be a 1972 65hp engine.

The air silencer has a 1976 sticker on it along with the timing info. The boat was a 1977, and the engine cover says 70HP

What gives??
 
E

ezeke

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12,532
Re: Engine swap advice needed.........

Don't rely on the stern bracket label; see what's on the welch plug on the engine block. Is the motor electric shift? The same stern brackets were used on many models well into the 1980's so it could just be one that was replaced.
 
M

mrcj001

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Re: Engine swap advice needed.........

Where is the welch plug??

Its not electric shift, it has two cables , one for the throttle, one for the shifter.
 
E

ezeke

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Re: Engine swap advice needed.........

mrcj001 said:
Where is the welch plug??

Its not electric shift, it has two cables , one for the throttle, one for the shifter.
Click to expand...

The welch plug is aluminum, nickel sized, convex - on the block.

The 1972 65HP motor was electric shift.
 
M

mrcj001

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Messages
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Re: Engine swap advice needed.........

The number on the welch plug is:

Top #
70673D

Bottom#
J001251

I really need to know the correct engine so I can get the right service manual and parts.
 
1

1kruzer1

Petty Officer 2nd Class
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Apr 26, 2008
Messages
110
Re: Engine swap advice needed.........

No stock tell-tale on that motor. I strongly suggest a new impeller so you know where you're at and don't fry it. Tell tale is very easy to add to this motor, if you want it. Same motor as mine.
 
M

mrcj001

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Messages
313
Re: Engine swap advice needed.........

Thanks for the info:

I will update later as I progress.

I just need to get the damn wasp nest out of the donor boat.:cool:
 
M

mrcj001

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Jul 25, 2008
Messages
313
Re: Engine swap advice needed.........

Well, got the engine swap done. Had to modify the lifting plate for the tilt unit. all in all, was pretty stright forward.

I changed the water pump and have a question:

How would I know for sure that the water tube connected properly when I re-installed the lower unit?

Here is why I ask:
I ordered a new t-stat and when I removed the t-stat housing, there was NO t-stat. I installed the new t-stat and hooked up the hose to check my work. There is water coming from the prop exhuast and from just above the lower unit on both sides. Very strong flow. There seems to be a small pee hole in front of the lower unit itself and water flows just fine.

How warm is the t-stat housing and the heads going to get. I can only keep my hand on for about 3-5 seconds before getting burned.

I dont want to overheat the engine.


Here`s some pics of the swap:

006-4.jpg



007-2.jpg



008-3.jpg



009-4.jpg
 
E

ezeke

Supreme Mariner
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Sep 19, 2003
Messages
12,532
Re: Engine swap advice needed.........

The motor should run within 15 degrees of 140 degrees at all operating RPM. You should be able to keep your fingers on the head for a full three count any time the engine is running. Keeping your fingers on 140 degrees longer than a three count risks third degree burns.

You may want to consider 1. installing a temperature gauge, 2. purchasing a laser hand help thermometer like a Raytec MiniTemp, or 3., installing a tell tale.

All of the three cylinder engines have a tendency toward getting air in the cooling system when the tell tale outlet is not located high on the engine, so try to fit it high if you add one.
 
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