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View Full Version : PCM 351 Update and Repair Questions


CameronCarey
12-27-2008, 11:00 PM
So i have two items that will absolutely need to be addressed before i hit the water again.

the engine is a 77 Pleasure craft 351...

The ring gear on my flywheel is trashed........and the flywheel isn't in that great of shape either.

Does anyone know if this is a unique part?
skidim sells the ring gear and probably the flywheel....but it seems unreasonably expensive....(i say that as i can buy billet machined race flywheels for less)
what makes the flywheel special.......it appears to be a standard ford 157 tooth flywheel?

the second is the alternator........i have what appears to be an automotive alternator installed on my boat........i would like to convert it to a one wire Delco Marine 100amp unit.......has anyone done this? how is the choke wired with the one wire alternator setup?


Any and all advice or comments are appreciated!

CameronCarey
12-28-2008, 01:12 AM
I found a post discussing the flywheel that i had not seen earlier......what i gathered is that its a standard ford part..........Guess ill hit up NAPA/Orieley/autozone tomorrow and see if they have one...

Bellinghamster
12-28-2008, 10:54 AM
With only a starting battery (i.e. no large "house" battery bank or large loads, like a winch), I see no advantage to upsizing to a 100A alternator. A typical starting battery (~85AH) will only accept 30 or so amps for a short period of time before tapering off (depending on it's state of charge).

The stock wire harness runs the alternator output through the 50A breaker on the back end of the engine on it's way to the battery. If you battery is mostly discharged but in very good condition and manages to fire off the engine, and you have a large alternator capable of pumping out everything the battery will accept, you might get enough charge current to pop the breaker. Suddenly unloading a alternator while it's at full field can/will cause a voltage spike that may take out alternator diodes, electronic ignition and a stereo system (assuming there's not much else in the way of sensitive electronics) - anything that gets it's power from the harness... just something to be aware of.

All that said, you should definitly get a marine alternator on there. The automotive ones don't have spark arrestors fitted and are not legal for use on gasoline engines in enclosed spaces ((i.e inboards). A good alternator shop can retrofit a flame arrestor on any delco for ~$20-30.

The carb choke should get it's power from the "purple" wire (hot when key is in run position), but not after the ballast resistor (which is used to drop the voltage to the coil once the engine is running - not always used with modern coils/electronic ignition).

A one wire alternator connects almost the same as the old one, just leave off the exitation (green wire in the diagram below). Thanks to TRBenj for creating the diagram.

FI skier
12-28-2008, 11:33 AM
Cameron I have a stack of 351w Flywheels with good starter rings.
I can be reached thru Florida Inboards Inc. 850 215 1996
Also please do not install automotive electrical or fuel related non ignition protected products on your inboard boat. I can also quote you on a alternator.
www.floridainboards.com. I am in Panama city Florida.

Jody

CameronCarey
12-28-2008, 11:45 AM
I do not have a breaker in my system currently...If there was one(which i suspect) i do not know where it was mounted...i will look into that today

CameronCarey
12-28-2008, 11:50 AM
Cameron I have a stack of 351w Flywheels with good starter rings.
I can be reached thru Florida Inboards Inc. 850 215 1996
Also please do not install automotive electrical or fuel related non ignition protected products on your inboard boat. I can also quote you on a alternator.
www.floridainboards.com. I am in Panama city Florida.

Jody

I will give you a call on Monday...........I would not install anything without proper spark containment.......right now i am just working through what came on the boat when i bought it.

Cloaked
12-28-2008, 12:42 PM
I will give you a call on Monday...........I would not install anything without proper spark containment.......right now i am just working through what came on the boat when i bought it.

I am enjoying watching you enjoy your project. :cool::)

TMCNo1
12-28-2008, 06:05 PM
With only a starting battery (i.e. no large "house" battery bank or large loads, like a winch), I see no advantage to upsizing to a 100A alternator. A typical starting battery (~85AH) will only accept 30 or so amps for a short period of time before tapering off (depending on it's state of charge).

The stock wire harness runs the alternator output through the 50A breaker on the back end of the engine on it's way to the battery. If you battery is mostly discharged but in very good condition and manages to fire off the engine, and you have a large alternator capable of pumping out everything the battery will accept, you might get enough charge current to pop the breaker. Suddenly unloading a alternator while it's at full field can/will cause a voltage spike that may take out alternator diodes, electronic ignition and a stereo system (assuming there's not much else in the way of sensitive electronics) - anything that gets it's power from the harness... just something to be aware of.

All that said, you should definitly get a marine alternator on there. The automotive ones don't have spark arrestors fitted and are not legal for use on gasoline engines in enclosed spaces ((i.e inboards). A good alternator shop can retrofit a flame arrestor on any delco for ~$20-30.

The carb choke should get it's power from the "purple" wire (hot when key is in run position), but not after the ballast resistor (which is used to drop the voltage to the coil once the engine is running - not always used with modern coils/electronic ignition).

A one wire alternator connects almost the same as the old one, just leave off the exitation (green wire in the diagram below).

Please be aware when posting the wiring diagram shown, as I have been made aware of it's origin and it's use without credit for it's existence.
"A Correct Craft owner went through all the trouble to create the diagram- maybe it would be worthwhile to ask them to share it in its native format so others could benefit from it... or at the very least, give them credit for authoring and posting it here on Teamtalk."
I drew that diagram. I would NOT recommend following it blindly. Follow the instructions included in the EI kit as to whether or not to bypass the resistor. In my experience, the Prestolite/PCM kit usually has you bypass the resistor, while Pertronix kits will vary. It is also important to match the coil to the module. Again, I recommend that anyone installing EI follow the instructions in their specific kit.
How nice. No credit to the author?

CameronCarey
12-28-2008, 06:18 PM
Back to the cinciut breaker thing.........my last project was a 76 arrowglass stingray with a mercruiser outdrive......it had a breaker........but the litrature i have (vintage to 77) for this engine does not show a breaker on this motor...........is there a CFR that requires it on new boats?

the best i can tell the purpose would be to keep a shorted starter from welding itself and super heating the engine compartment.

Comments suggestions insight???

CameronCarey
12-28-2008, 06:26 PM
why wouldn't the breaker be on the starter side of the starter solenoid? most solenoids are rated for 150 amps.......or would the surge pop the breaker when it engages?

not challenging the logic just trying to understand it

Bellinghamster
12-28-2008, 08:40 PM
Sorry for the lack of credit on the wiring diagram. Unfortunately I don't remember where I stumbled on it. Just one of many files in my Mastercraft info folder.

Cameron - the breaker is to protect the engine wiring harness and dash wiring. The starter is unprotected. I recall cranking current can be upwards of 400A, so a breaker for it isn't really practical.

JohnE
12-28-2008, 08:44 PM
Please be aware when posting the wiring diagram shown, as I have been made aware of it's origin and it's use without credit for it's existence.

C'mon Harold. You know that you are subject to more rules than the rest of us.:D

At least it seems that way sometimes.........

CameronCarey
12-28-2008, 09:11 PM
so the hot side of all the dash wiring is fused for the most part in my new harness, the only exceptions are the tach...which uses a hot signal and the voltmeter. The concern about the diodes seems like something i should think about though......the fix would be a big diode .......or a breaker on that line....hummm

CameronCarey
01-04-2009, 07:57 PM
I looked into the breaker problem.......its very feasible.......my alternator came with a spec sheet including output vs RPM at engine idle (800 RPM) the alternator RPM is about 2000 RPM ....the alternator puts out a current of around 68 amps....so if that current crossed the breaker it would always pop it..............if the battery was nearly dead...

interesting problem since any upgraded alternator would require a bigger breaker..

CameronCarey
01-04-2009, 08:11 PM
Walking the dog................ i thought of another solution.....I could use a larger pulley on the alternator...........for me that would mean about a 3" pulley which would get me down around 1500 alternator RPM at idle.......and a peak current of 40A.....

the catch is.......if i know the battery is nearly dead.......i need to idle for a bit before i take off...


so if i want to add a breaker...........i need a bigger pulley

Hollywood
01-13-2009, 06:51 PM
Woah, slow down there. I think you need to think your wiring through a little. I will check in to it later.

CameronCarey
01-13-2009, 09:17 PM
So i thought i would give a project update with some pictures

Here is what I've done so far

The rear main seal was replaced along with the oil pan gasket
New brass freeze plugs installed (with red loctite)
The block and heads cleaned and painted bright red (i did not pull the heads)
The intake is installed with stainless intake bolts and new marine gaskets
The cleaned distributor is re-installed in the original position
the Carburator was cleaned and re installed with an adapter, and spacer wedge with a total of 3 gaskets (two Holley one Edilbrock
The flame arrestor was disassembled, cleaned and re-assembled (i may replace this anyway)
the New Delco 1 wire marine shielded alternator is installed with slightly modified original brackets
Most bolts have been replaced with grade 8 or stainless fasteners depending on the application and required strength
the sporty fully polished vintage Holley cast Aluminum valve covers are installed with new gaskets
the PCM throttle bracket is installed (the base is installed the rest is just finger tight)
the water pump and crankshaft pulleys were bead blasted and painted along with the alternator brackets.....(one of the support plates i dont like the color choice though ........im taking it back off to clean it again and paint it red)
The water pump bracket was cleaned and painted

Whats shown but not complete
The distributor cap and wires were re-installed.........although i will probably replace both before it actually hits the water.
The coil is just sitting there ( a stainless bracket was located.....it just hasn't arrived yet)
the Breather filter is there but, just looks bad to me.........i just haven't bought a replacement yet........the same goes for the PCV valve

The hoses for the crankcase ventilation features are now a bit short........and need to be replaced anyway.

The raw water pump was taken apart and cleaned.....more on that later

CameronCarey
01-13-2009, 09:21 PM
Port side, nasty breather filter to be replaced..............one of the spark plug boots broke on dis assembly.........these wires are also just a bit short. they are on the replacement list.

CameronCarey
01-13-2009, 09:30 PM
on the starboard side you might notice the "Motorcraft" automotive alternator has been replaced my something sliglty more coast guard compliant. Thanks to Mike B (a coworker) who welded the extension on my stock bracket to make everything line up......

The Delco mounting boss is a bit closer to the alternator housing, a bit shorter and has a smaller bolt......the extension welded on is a piece of 3/4" rod which i drilled and tapped for the 3/8x 16 Delco sized alternator bolt.............i could have bought a new bracket ..........but id rather not .......I've got enough things to spend money on here.

The only thing i want to do different on the alternator bracket is the stabilization bracket (sheet metal bracket closest to the viewer) I should have painted it red......this will likely be fixed by the time i post pictures again


The thermostat housing still needs to be sandblasted..........i just mocked it up to check clearance to other things in the area.......new gaskets, and a 160 degree thermostat are already purchased. ...............ironically i have a great bead blast setup.....but ive got to go buy a cheap sand blaster to finish this task (tractor supply here i come)

CameronCarey
01-13-2009, 09:31 PM
One other Note
The studs on the water pulley are just temporary (i ordered some SS allen screws and they have not yet come in yet........5/16x24 is not a common stainless bolt in these parts

CameronCarey
01-13-2009, 09:38 PM
The raw water pump...........
I think this is a topic for a new thread....

http://www.mastercraft.com/teamtalk/showthread.php?p=569273&posted=1#post569273