Hi all.  Subject vessel is a 1972 Commander '41 with mighty 427's and closed cooling.  I am performing some deferred service to hopefully resolve some cooling and drivability issues.  In a separate thread, I de-Bubba'd my raw water cooling systems and finally have proper flow through both engines, each idling at 165F; which is right in spec with the manual.  Now, once I bring her up to 2000 she creeps up to about 175 (both engines).  If i bring her up to 3000 she'll lay over, almost like in a car when you have a backfire out the carburetor and the engine goes flat.  I back off the sticks and ease her slowly back up to 3000 and she'll go.  In parallel, the port engine stays at 175F and the starboard creeps to 185-190F.  Back her down to 2000 and both engines return to 175F.

I wasn't able to have anyone monitor the engines while underway, so I had only my gauges, eyes and ears to collect this data.  I can't be sure if both engines laid over or just one, but as you can imagine losing power on one side while attempting to get on plane probably feels pretty close to losing both.  The boat just nosed down.  The engines never stalled however.

My first thought is fuel system.  I have holley electric pumps, a Racor dual canister system with vacuum gauges for each engine.  The carburetors are marine Edelbrocks.  No sign of an anti-syphon valve on either tanks.  Choke wide open.  Could the secondaries not be opening?  I believe the late Commander Morland says the original carbs open secondary metering around the 3000 RPM mark, but I'm not sure if that applies to the Edelbrocks.

Second thought is the ignition system.  Mallory electronic ignition conversion, with new pickups, caps, rotors.  New spark plugs.  No miss, hesitation or anything on or off idle, no vibration (which is like a jackhammer through those Paragons)...very smooth through the lower power range.

Now on the way home, basking in my glory of my successful raw water impeller replacement and subsequent cooling benefits, it came to me that could my distributors not be advancing?  Could they be stuck at base timing?  If so, it would explain why the engines run so good at lower RPM, but so crappy at cruise.  Also, I wonder if the excess heating I'm seeing is a result of retarded timing?  At 3000 RPM the distributors should be adding like 10 degrees of advance.  If its adding none or a negligible amount, could this be my problem?

I know the next suggestion is to go check the timing on these engines.  That is my plan, but I can't get back to do so until next Saturday, so I'm trying to harness the brain trust of this forum to formulate a plan of attack.

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Trying this for now.  Probably won't see near full throttle for a while, but it is easy to change things on this boat if needed.

The carb jet in the pickup line was threaded M4x.7, common thread.  I put stainless setscrews in with Threadlocker Red, don't want them falling out.  One setscrew bottomed out without going in deep, the other went in deeper than I'd like, blocking flow a little, but still more flow area than my valves.  I might find short stainless button-head stainless screws instead, if I feel like taking them apart again.  I think the carb jets stuck into the flow a bit anyway.

I think I used a 27mm socket on the pickup, same size hex on the much older pickup from the woody I looked at yesterday.

Best thing was getting a look inside my tanks.  No rust after sitting for decades!

I concur with page 14.  I just find it odd that Racor specifies the (only) filter that works with our housings, is rated for 5.5 psi LESS than the housing itself.  

I also agree that there doesn't seem to be an aftermarket marine fuel system roadmap to follow.  I think each boat is different and had different needs.  

Lastly, I'm also not one to argue with results.  If this solution didn't work than you wouldn't be promoting it.  As previously mentioned, I am reaping the luxury of someone else's trial and error, and I am not looking this gift horse in the mouth.

I am going down to the boat this weekend to put a parts list together.  Right now my distribution panel is as shown earlier in this thread, with my pumps and regulators mounted next to the engines facing center.  My plan is to:

  1. Remove the regulators and install the pumps on the distribution panel. 
  2. Install 100 micron filters at the petcock of each tank outlet. 
  3. Leave factory anti-siphon unrestricted (?). 
  4. Plumb the outlet of the pumps to each inlet of the distribution manifold.
  5. Plumb from the filter outlets directly to the carburetor.   
  6. Plumb the carburetor vapor return directly to the pump. 
  7. Replace the Racor vacuum gauges with the pressure gauges from the pressure regulators no longer being used.
  8. Replace all Racor elements for good measure.

Anything I'm missing?

What 100-micron filters?  I looked for some with threads on inlet and outlet to put between the valve and pump inlet, didn't find any.  Could simply go from valve to rubber hose to filter to pump, but I don't have a ton of room and it is already cluttered.

John Mario said:

I concur with page 14.  I just find it odd that Racor specifies the (only) filter that works with our housings, is rated for 5.5 psi LESS than the housing itself.  

I also agree that there doesn't seem to be an aftermarket marine fuel system roadmap to follow.  I think each boat is different and had different needs.  

Lastly, I'm also not one to argue with results.  If this solution didn't work than you wouldn't be promoting it.  As previously mentioned, I am reaping the luxury of someone else's trial and error, and I am not looking this gift horse in the mouth.

I am going down to the boat this weekend to put a parts list together.  Right now my distribution panel is as shown earlier in this thread, with my pumps and regulators mounted next to the engines facing center.  My plan is to:

  1. Remove the regulators and install the pumps on the distribution panel. 
  2. Install 100 micron filters at the petcock of each tank outlet. 
  3. Leave factory anti-siphon unrestricted (?). 
  4. Plumb the outlet of the pumps to each inlet of the distribution manifold.
  5. Plumb from the filter outlets directly to the carburetor.   
  6. Plumb the carburetor vapor return directly to the pump. 
  7. Replace the Racor vacuum gauges with the pressure gauges from the pressure regulators no longer being used.
  8. Replace all Racor elements for good measure.

Anything I'm missing?

You absolutely could.  Connect it any way that is practical.  The purpose of this filter is to protect the pump from damage by sediment or whatever else might be swimming around in your tanks.  I’m installing these filters at the tank outlets because its accessible and space allows:

John,

is that a 110v outlet in you fuel tank compartment? Could be very dangerous, possible explosion should there ever be a spark.  I’m aware that an outlet in the bilge/engine compartment is not legal. You may want to check this out.

I already disconnected it - its a dead outlet.  That was among the first things I did when bought the boat. 

Joe Marino said:

John,

is that a 110v outlet in you fuel tank compartment? Could be very dangerous, possible explosion should there ever be a spark.  I’m aware that an outlet in the bilge/engine compartment is not legal. You may want to check this out.

I have a 110V outlet in the bilge of my 31', and had a few in the bilges of the 2004 I sold recently.  I plan to use the outlet in my 31' for my battery charger, but could hard-wire it in, if an outlet is not allowed in the bilge.  You sure they aren't legal?

Joe Marino said:

John,

is that a 110v outlet in you fuel tank compartment? Could be very dangerous, possible explosion should there ever be a spark.  I’m aware that an outlet in the bilge/engine compartment is not legal. You may want to check this out.

Here is an article that addresses the dangers of improper bilge wiring/electrical issues:

https://www.westmarine.com/WestAdvisor/Ten-Deadly-Conditions

While I do not profess to know all the legalities of bilge/engine room wiring, I have seen two boat explosions related to use of 110 volt in the bilge where people were seriously burned. I had an ABYC Surveyor write up a boat I was purchasing. It involved a battery charger and a 110 outlet. He recommended it be removed and replaced with hard wiring. The boat was older and I had to replace all Other 110v outlets with GFI outlets. I doubt an Insurance company would pay a claim for a 110v related bilge fire, especially in a gasoline powered boat. Regardless of it being legal, I believe anything that could cause a spark that could cause a fire onboard is dangerous. Let’s all stay safe.

I guess I'll switch my battery charger to hard-wire then.  The outlet originally was to plug in the fridge in the bilge, that's how it was built at the factory.  The fridge looks to be unused, but I don't think I'll use it, so I can hard-wire my battery charger into that circuit.  I plan on switching my outlets or my breaker to GFCI, winter project.

Joe Marino said:

Here is an article that addresses the dangers of improper bilge wiring/electrical issues:

https://www.westmarine.com/WestAdvisor/Ten-Deadly-Conditions

While I do not profess to know all the legalities of bilge/engine room wiring, I have seen two boat explosions related to use of 110 volt in the bilge where people were seriously burned. I had an ABYC Surveyor write up a boat I was purchasing. It involved a battery charger and a 110 outlet. He recommended it be removed and replaced with hard wiring. The boat was older and I had to replace all Other 110v outlets with GFI outlets. I doubt an Insurance company would pay a claim for a 110v related bilge fire, especially in a gasoline powered boat. Regardless of it being legal, I believe anything that could cause a spark that could cause a fire onboard is dangerous. Let’s all stay safe.

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