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Project 5.7 to 7.4 swap. Help me to finish it!

S

Simonas

Member
Hello all,
I'm in the project to swap my 5.7 to 7.4. Boat is 1987 Sea Ray Sundancer 268.
I had cracked my 5.7 block, and prior to this it had some knocking noise, so I'm not very interested to change block and hear the same sound again. During the winter, I've bought 7.4 as non runner, and partially incomplete. Disassembled, found stuck rings on one piston, assembled it back, fired up with basic wiring and left it in my shed.
Now the time is coming to get my boat going again, and I think to put that 7.4 in. There are couple of issues with it, and I hope, that with Your help I'll be in the water briefly.

I've decided to use 7.4 pulleys, but now find out, that 2 of them are different from 2 others. So disassembled pulleys, and now will go for 5.7 serpentine belt pulleys. There's an issue with circulating pump, as it will be driven counterclockwise with serpentine belt. Should I worry about that?

Also I'm unable to find location where to put oil pressure switch.
One set up like that: https://www.google.lt/search?q=merc...UICigB&biw=1256&bih=655#imgrc=tusAR8-zj6v3tM:
comes above oil filter.
But I have another one like this:
https://www.google.lt/search?q=merc...UICigB&biw=1256&bih=655#imgrc=OoRLS-D4n7sPjM:
And don't know where to put it.


Seems all for now.
As I will work on this project everyday, I will post updates and more questions.

Thanks in advance in Your participation.
 
Where you install it is not really an issue, as long as you have it somewhere. It shuts off fuel pump if oil pressure goes south. Wherever is most convenient.
Unclear about the pulley issue you don't provide enough info to go on. I think big block circulating pumps are bidirectional.
You will also want to change the engine mounts the ones for the 350 are a bit smaller.
 
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Simonas said:
Hello all,
I'm in the project to swap my 5.7 to 7.4. Boat is 1987 Sea Ray Sundancer 268.
NOTE: You will be installing more HP and Torque than what the A drive is normally capable of handling.
While this would not solve the A drive issue, I would have built a SBC in the 6.3L version. Less weight and no issues with the accessories.

I had cracked my 5.7 block, and prior to this it had some knocking noise, so I'm not very interested to change block and hear the same sound again. During the winter, I've bought 7.4 as non runner, and partially incomplete. Disassembled, found stuck rings on one piston, assembled it back, fired up with basic wiring and left it in my shed.
Now the time is coming to get my boat going again, and I think to put that 7.4 in. There are couple of issues with it, and I hope, that with Your help I'll be in the water briefly.

I've decided to use 7.4 pulleys, but now find out, that 2 of them are different from 2 others. So disassembled pulleys, and now will go for 5.7 serpentine belt pulleys. There's an issue with circulating pump, as it will be driven counterclockwise with serpentine belt. Should I worry about that?
Make sure that your engine coolant circulating pump is bi-directional.

Also I'm unable to find location where to put oil pressure switch.
this will be a N/O low oil pressure switch. N/O = normally open.

One set up like that: https://www.google.lt/search?q=merc...UICigB&biw=1256&bih=655#imgrc=tusAR8-zj6v3tM:
comes above oil filter.

But I have another one like this:
https://www.google.lt/search?q=merc...UICigB&biw=1256&bih=655#imgrc=OoRLS-D4n7sPjM:
And don't know where to put it.


Seems all for now.
As I will work on this project everyday, I will post updates and more questions.

Thanks in advance in Your participation.
Click to expand...
 
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Simonas said:
Yes, I know about HP, but I have no other choice for today.
I would budget myself for an eventual stern drive replacement.

How do I make sure it's bi-directional? It has no serial number on the front. If I post picture, would it help?
You would need to remove the rear cover and look at the metal impeller. The bi-directional impeller will have rather straight blades on it.
Click to expand...
 
look along the top of the oil pan mounting surface, on the LH side, and you will find several pipe 1/8"NPT plugs (probably with hex sockets) towards the flywheel....these are fed from the main oil galley....
 
RicardoMarine said:
...............
Click to expand...

I have just reassembled circulating pump, and it was very difficult to determine if blades are straight, so I'm not very eager to put it to pieces again. If I turn it with power tool, it is possible to determine it is bi-directional, or not?

Regarding switch, I have one possible place, at the top of flywheel, it an oil passage, but something whatever was there is broken, so I'm not able to use that location. I could maybe drill it out, but then I have to change the oil.
https://farm2.staticflickr.com/1725/27642162347_35be874f1b_z.jpg
 
Bump what? Your questions have been answered.
To recap: Yes big block water pumps are bidirectional. Install oil switch in a brass T.
 
Because there are so many twin engine installations of the big block, the water circulation pumps ar bidirectional (CW and CCW). If you were buying an automotive type pump they probably are not. Marine yes. They should have bronze impeller and stainless back cover.
Crusader in particular, along with Mercruiser, VP, and a few others have propulsion packages that use this engine. Gazillions in use out there (or probably just sitting....)
 
o2batsea said:
Because there are so many twin engine installations of the big block, the water circulation pumps ar bidirectional (CW and CCW). If you were buying an automotive type pump they probably are not. Marine yes. They should have bronze impeller and stainless back cover.
Crusader in particular, along with Mercruiser, VP, and a few others have propulsion packages that use this engine. Gazillions in use out there (or probably just sitting....)
Click to expand...

Ok, so I will not worry about than, and will go for serpentine belt.
Thank You.
 
...........................
Simonas said:
I have just reassembled circulating pump, and it was very difficult to determine if blades are straight, so I'm not very eager to put it to pieces again. If I turn it with power tool, it is possible to determine it is bi-directional, or not?

You can quickly solve your delima by purchasing a Marine bi-directional Circ Pump.
(some call these "water pumps"..... but they are actually an "engine coolant circulating pump")

Regarding switch, I have one possible place, at the top of flywheel, it an oil passage, but something whatever was there is broken, so I'm not able to use that location. I could maybe drill it out, but then I have to change the oil.
https://farm2.staticflickr.com/1725/27642162347_35be874f1b_z.jpg


On the Port side of the engine, and close to and above the area where you will find the OEM oil filter, there will be a port for this N/O Low Oil Pressure Switch.
This port leads directly into the oil galleys.

Remember..... this will be a N/O low oil pressure switch..... not a sending unit nor a warning light switch.
It will have 2 connectors on it.
Click to expand...
 
RicardoMarine said:
...........................
Click to expand...

It's not a quick solution, because of my location (not updated profile). When I turn it by hand, with hose off, it spits water, no matter witch side I'm turning, so I guess it should work?

I'll try to fix that oil galley and put that switch there.

+
Strange thing happened, while I was running it on water hose. I've put hose straight to thermostat housing (no raw water pump in my application), turned on water, started engine, then shut engine, and left water on. Cylinders filled with water. How does that happen? When repeated (after cleaning) everything, except turned water off first, than shut engine- no problem, whatsoever.
 
OMG!Now you must perform a flooded engine recovery which means several cycles of running the engine up to operating temperature, allow it to cool and change the oil. at minimum twice
 
o2batsea said:
OMG!Now you must perform a flooded engine recovery which means several cycles of running the engine up to operating temperature, allow it to cool and change the oil. at minimum twice
Click to expand...

That's ok, but how did that happened?
Also how does that affect oil? I don't see any water in oil.
 
Hello again,
no answer how it happened, huh?

Anyway, moving forward, trailed engine across the country and now it's in the boat. Now I have to finish wiring. It's pretty straight forward, only couple of questions:
1. Alternator wiring diagram says different colors, than my harness has.
https://farm2.staticflickr.com/1767/29046478898_c0a35b7cc0_m.jpg
Also alternator connected with two relays, and I have one small 2pin connector free. Take a look at the photos.
https://farm2.staticflickr.com/1824/42870073042_378539c257_z.jpg

2. Oh, and it won't crank, not even clicking. Checked ignition- fine, slave solenoid has 12V, if I short it, engine cranks fine, but not with the key.

P.S.: is there any way to post photo in the forum?
 
When you turn the key, + 12 volts is applied to a wire that goes directly to one of the solenoid COIL terminals ( the small one).... if the other lead on the solenoid has a good contact to ground AND the solenoid is good. It should crank when you turn key to start. Simplest possible electrical circuit. You've already proved starter works.

Possible issues..
Bad start switch,
Bad wiring
No ground @ solenoid
bad solenoid
 
Simonas said:
That's ok, but how did that happened?
Also how does that affect oil? I don't see any water in oil.
Click to expand...


re: "Strange thing happened, while I was running it on water hose. I've put hose straight to thermostat housing (no raw water pump in my application), turned on water, started engine, then shut engine, and left water on. Cylinders filled with water. How does that happen?"

When the engine runs, gas escaping from the exhaust ports helps to prevent water from back flowing into the cylinder heads. If engine equipped with shutters in the exhaust running engine keeps the then open... There is back pressure/resistance in the exhaust path that is more than the very slight resistance for the water in the elbows to run uphill into the exhaust path itself and into the engine.

PERSONALLY, I never advise running an engine unless the RAW WATER pump regulates the rate at which the water flows into an engine. I'm not even a fan of muffs. While I have an engine mounted raw water pump and a T valve setup in front of it, I NEVER attach a hose directly to the input of the pump. I have a 5 gal bucket that I keep a water hose refilling, while a separate hose runs from the inlet of the raw water pump into the bucket. Engine only gets the water it needs...no more.


RE: OIL.... it is unlikely that no water got into the oil... The water in the oil won't be visible until you run the engine and it mixes to a milky color. Water in clyinders will run downhill into the crank... Turning the motor over will force water in the cylinders into the crank. Changing the oil is a precaution at a minimum... If the cost/time of an oil change is bothering you... get another hobby.
 
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Well Bob that was a month ago so the engine has probably gotten significant rust damage by now if the OP hasn't done the flood mitigation thing.
 
Guys, I was unable to run it to operating temperature, so didn't changed oil yet, but I hope I will in a couple of days. Got stuck with fuel pump/ alternator wiring issues, as mentioned above.
Any advice is much appreciated.

I've tested slave solenoid and it's dead. Connected two wires temporary.

Engine is in the boat, boat is in the water, so we're getting somewhere. Not ideal situation, but it never is.
 
Ok, now I'm finishing to set up wiring.
Could somebody tell me, what is the point of 2 relays for wiring electric fuel pump? One relay powers up, when ignition turned on, and it sends power to second relay, which turns on fuel pump, when starter solenoid is working. Why the first relay is necessary? Started will never spin without ignition, anyway?
 
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Simonas said:
Guys, I was unable to run it to operating temperature, so didn't changed oil yet, but I hope I will in a couple of days. Got stuck with fuel pump/ alternator wiring issues, as mentioned above.
Any advice is much appreciated.

I've tested slave solenoid and it's dead. Connected two wires temporary.

Engine is in the boat, boat is in the water, so we're getting somewhere. Not ideal situation, but it never is.
Click to expand...

Re: engine up to operating temp.... that is a "nicety" at normal oil change intervals, however when the engine gets water in it, the goal is to get the water contaminated oil out of the engine
ASAP WITHOUT circulating it throughout the engine... likely a moot point by now... see post #26 for more details...
 
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