PCM 351W fresh water cooling (FWC)

I don't see any gazintas

Wilhelm Hertzog wrote:

I’d like to see how the cooling passages line up on those risers. Never seen that style before, though they are handsome. Manifolds look like normal PCM.

Gasket for reference:
https://www.skidim.com/images/RM0002.jpg

KENO wrote: As far as the distributor, it more a matter of spark protection. Where the advance mechanism goes through the distributor there's an opening that gas fumes can pass through and get into the distributor if you have a fuel leak. The fumes meet the spark in the distributor and you have an explosion that is not contained in the distributor because of that open unprotected path. The marine version has no vacuum advance and the opening is blocked off but there are a couple of vent holes in the body of a DUI HEI marine distributor that have brass screens in them which keep the explosion contained inside the distributor. The gas fumes can still get in if you have a leak but like mentioned above the screens prevent the internal explosion from getting outside the distributor so it keeps the fumes in the engine compartment from exploding. The distributor may be damaged internally, but you won't be in an exploding boat. It works on the same principle as an old miners lamp Here's a link down below to a thread by somebody who "converted" his Chinese distributor. In his mind it meets USCG requirements    The typical factory job has 2 layers of screen per vent hole, not 1 like he did. I think there's a reason for that Lots of people have survived for a long time without USCG approved stuff on their boat, but it just takes that one bad day to change all that. link Some later marine certified distrihbutors are well sealed with no openings for fumes to get into the distributor. By the way, is your engine normal automotive rotation or if it's reverse rotation, did you have some machine work done to adapt a reverse rotation gear to that distributor?

Reverse rotation. I can't recall if the PO installed the distributor or if it was done by the guys who rebuilt the motor for me. I suspect there was some machine work involved, yes.

It seems to me that the manifolds and risers are raw water cooled.

Instead of the raw water going in the front of the manifold, it goes in the rear and up through the riser and out the back of the boat.

As far as the distributor, it more a matter of spark protection.

Where the advance mechanism goes through the distributor there's an opening that gas fumes can pass through and get into the distributor if you have a fuel leak.

The fumes meet the spark in the distributor and you have an explosion that is not contained in the distributor because of that open unprotected path.

The marine version has no vacuum advance and the opening is blocked off but there are a couple of vent holes in the body of a DUI HEI marine distributor that have brass screens in them which keep the explosion contained inside the distributor.

The gas fumes can still get in if you have a leak but like mentioned above the screens prevent the internal explosion from getting outside the distributor so it keeps the fumes in the engine compartment from exploding. The distributor may be damaged internally, but you won't be in an exploding boat.

It works on the same principle as an old miners lamp

Here's a link down below to a thread by somebody who "converted" his Chinese distributor.

In his mind it meets USCG requirements   

The typical factory job has 2 layers of screen per vent hole, not 1 like he did. I think there's a reason for that

Lots of people have survived for a long time without USCG approved stuff on their boat, but it just takes that one bad day to change all that.

link

Some later marine certified distrihbutors are well sealed with no openings for fumes to get into the distributor.

By the way, is your engine normal automotive rotation or if it's reverse rotation, did you have some machine work done to adapt a reverse rotation gear to that distributor?

Wilhelm where does is hose that feeds the T come from?

How is the exhaust cooled?

Dry risers?

outerbanked wrote: Pics of your engine would help. I would want to know if they included your exhaust risers (the stock system did not). Have you done the bucket test with the raw water pump to ensure you are getting correct flow? Have you verified the temps with a infrared temp gun? Checked for kinks? Made sure the hoses are not collapsing under load? Coolant is at proper level?

May be wrong, but I believe the GT40 is a double pass. Where as, the 351w would be a single pass.

Here's a link to a thread on the bucket test

It's testing if the RWP is doing it's job.

Wilhelm,
Is the exchanger used or new? If used, has it been cleaned? They will "plate" ( a build up of impurities on the heat transfer surfaces) out over time loosing their efficiency.

Gary S wrote: Do you have the actual instructions or just the parts list? I obviously cannot speak for them but if you follow their instructions they want you to remove the risers from the manifolds to move the water inlets from the front to the back. You then need to change the gaskets. PCV valve hose needs to be longer and I suspect the valve it's self may be one with a 90 degree bend built in. Either way you would think they should be included but who knows.... If you need the instructions I have them but have no scanner,maybe I could take a picture of them and post if you need them.

Gary—if you replaced your iPhone since it took a drink on Deep Lake, there’s a built in scan feature in the camera function. Might be worth a look see. You are really helpful.

8122pbrainard wrote: Wilhelm, How hot is "too hot"? Regarding the size of the heat exchanger, you can't go totally by physical size. It's all about internal surface area and fluid flow rates.

Touching 220 degrees Fahrenheit.

So I eventually got all the parts together except the rear heat exchanger bracket (R090038). Also, the part number that I needed to order for the upper thermostat housing assembly (RB025009) was changed to RA025009. Something to do with the separate seal on the RB025009 (part number R047011) having given problems, so the design changed to incorporate a seal in the housing itself, which negates the need for R047011. Be that as it may, I had a rear bracket fabricated to fit the heat exchanger, and my motor is now FWC.

However, the guys who did the installation work for me commented that the size of the heat exchanger is surprisingly small. They are more used to working on Mercruiser motors, where heat exchangers for smaller capacity motors than mine are apparently typically about 50% larger. And subsequent to the FWC conversion, I am now having issues with the motor getting too hot after running at high RPM for a while and then pulling back to idle.

Has anyone else had similar issues? I'm thinking that I may need a larger heat exchanger...

Is that the upper (RB025009) or lower (R025004) thermostat housing that you have available?