Crank driven vs block mounted raw water pump pros/cons

[Scott Danforth]

must have done a few hundred heat exchanger setups in my prior life. you need to make sure the expansion tank is about 20% of the total system capacity. you need about 10% for draw-down and 6% for expansion.

is this a full system or a half system?

 

[IslandExplorer]

Don't have a pic but my friends is mounted to the bulkhead away from the motor

Haven't decided where to mount it yet but good to know that on the wall is a good option. I do prefer keeping the motor as uncluttered as possible so mounting coolant res on the bulkhead would be sweet.

 

[IslandExplorer]

must have done a few hundred heat exchanger setups in my prior life. you need to make sure the expansion tank is about 20% of the total system capacity. you need about 10% for draw-down and 6% for expansion.

is this a full system or a half system?

Experience is definitely a big plus. That capacity ratio is just what I needed to know, thanks! Definitely don't want an udersized exp tank.. Imagine it would boil over and/or blow a line or something pretty quick. Slightly oversized a bad thing? I have plenty of room.

I am planning to run a full system. This is part of why I want to be sure to run a big enough raw water pump that it should keep up with the cooling flow needed. Read that some surprisingly will overheat while idling bc of pump being too small/low idling pump output. Planning to run a Johnson F6B9. Do you think that might be sufficient? Believe it is used on much higher HP and bigger block V8 motors than mine so I was thinking it would be a good match but I don't really know.
Any thoughts on these points would be much appreciated.

 

[Scott Danforth]

The F6 is more than enough. It's for big blocks

The F5 pump is more than enough

A full system will require a 5" diameter heat exchangers or larger

For plumbing a full system it may be easier to run two in-house thermostats.

Water flow on raw water side..... from seacock and sea strainer would go to the raw water pump. From raw water pump to HX inlet. Raw water outlet to exhaust elbows

Water flow on glycol side. HX discharge to bottom circulating pump inlet. With a 3/4 line running to bottom of surge tank. This is the fill line. A spacer under the thermostat that runs 2 3/4" lines to the manifold supply the manifold discharge goes directly to the heat exchangers after the engine thermostat. The thermostat is sitting on top the spacer. The outlet of the thermostat ties in the two manifolds and runs to the heat exchanger.

Run orificed vent lines from the heads and manifolds to the deareation section of the surge tank.

You still need to run the inleg pump to keep the drive cool. Suck it in and discharge as a drive shower

 

[ROY WILLIAMS]

MERCRUISER ENGINE 302CU. DISTILLED WATER 50% ANTIFREEZE 50% ENGINE COOLANT heat exchanger. THE WATER OF THE DRIVE SHAFT PUMP PARTS. IMPELLER WATER PUMP, DRIVE SHAFT.

 

[IslandExplorer]

The F6 is more than enough. It's for big blocks

The F5 pump is more than enough

A full system will require a 5" diameter heat exchangers or larger

For plumbing a full system it may be easier to run two in-house thermostats.

Water flow on raw water side..... from seacock and sea strainer would go to the raw water pump. From raw water pump to HX inlet. Raw water outlet to exhaust elbows

Water flow on glycol side. HX discharge to bottom circulating pump inlet. With a 3/4 line running to bottom of surge tank. This is the fill line. A spacer under the thermostat that runs 2 3/4" lines to the manifold supply the manifold discharge goes directly to the heat exchangers after the engine thermostat. The thermostat is sitting on top the spacer. The outlet of the thermostat ties in the two manifolds and runs to the heat exchanger.

Run orificed vent lines from the heads and manifolds to the deareation section of the surge tank.

You still need to run the inleg pump to keep the drive cool. Suck it in and discharge as a drive shower

Wow, thanks for the awesome detailed writeup on how to set this up, I really appreciate it. I can picture what your saying here. I am going to draw up a rough sketch of the proposed plan before I build it so I don't screw up the flow design and waste expensive hoses. Just got the F6 pump in this AM.

 

[IslandExplorer]

New crank driven F6B9 raw water pump just arrived.

 

[IslandExplorer]

Now I'll need to figure out my harmonic balancer and pulley combination that will work with this pump and my v belt marine alternator and circulator pump. The newer engine has a different imbalance so I can't run the Merc 188 part as is. Newer engine has a serpentine drive pulley on the blanacer that I need to swap over to a V.

Newer engine has 4 bolts holding serpentine pulley on.

The 70's 302 had this one with 3 bolts.
Wonder if it is hub centric and I can just drill it to match..

 

[Scott Danforth]

I made a delrin ring to make my F6 hub-centric to the new SFI rated damper.

I would seriously get a new damper as the rubber is coming out of that one.

 

[IslandExplorer]

I made a delrin ring to make my F6 hub-centric to the new SFI rated damper.

I would seriously get a new damper as the rubber is coming out of that one.

Oh I'm not using that damper, it was from the old engine that was left to the weather for 15-20 yrs and looks terrible like you said..
Plan to use the one that is on the engine already and hoping to fit the old v belt pulley onto it, replacing the serpentine pulley. I like the idea of the delrin ring, I really need to get a lathe.

 

[IslandExplorer]

Bad news on the heat exchanger I have...
It's only 4" diameter by 27" long so it must've been a half system HX. I'll need to source a good deal on a larger used HX for this full system.

 

[IslandExplorer]

I saw this one at the consignment that says it's for a 454. Looks like a seakamp maybe? Has the built in surge tank and plumbing that I believe splits the raw water outlet into 2 for the risers. Thinking if this measures in at ~ 5 x 21 it just might be the ticket.

 

[IslandExplorer]

HX acquired. It was supposed to be from a big block Crusader. Stark differences from the other one I sourced. This thing weighs in at a beefy 44 lbs! Hoping this with the F6B9 feeding it will be more than enough to keep my 302 nice and cool.

 

[ROY WILLIAMS]

50% distilled water/antifreeze 50%. heat exchanger engine coolant.