Can't get starboard engine to run after a bunch of work.

[achris]

Coils are not marine specific. All it needs to be is one that is specified as 'use with external resistor', and have the correct primary resistance. Distributors are very much 'marine specific'...

The standard coil setup on your 165 Mercruiser engine is:- from the key the power goes to a resistance wire (this would take the place of a ballast resistor), then into the positive terminal of the coil (the coil DOES NOT have an internal resistor)... You also have a wire from a terminal on either the starter solenoid or the starter motor itself, straight to the coil positive. That is so when the engine is being cranked, the coil gets full battery voltage (which will have dropped to about 10 volts because of the starter motor load). If the power only went through the ballast wire/resistor during cranking, the voltage at the coil may be too low to produce a healthy enough spark to start the engine.

The resistance wire is about 1.8 to 2Ω, and the coil primary resistance is between 1.1 and 1.5Ω. It does sound like the resistance wire has failed (engine runs while the key is held at START but dies when released to the RUN position), but you can still buy a new one from Merc. The part number is 84-94227A2... That would keep the engine as 'original' as possible. If you wanted to just replace the resistance wire with a ballast resistor, you could do that instead. Just get a normal wire and replace the resistance wire, and run that into the ballast resistor, then the coil positive. Same result. Swapping coils and distributors isn't going to help.

Chris...........

 

[ttownthomas]

Coils are not marine specific. All it needs to be is one that is specified as 'use with external resistor', and have the correct primary resistance. Distributors are very much 'marine specific'...

The standard coil setup on your 165 Mercruiser engine is:- from the key the power goes to a resistance wire (this would take the place of a ballast resistor), then into the positive terminal of the coil (the coil DOES NOT have an internal resistor)... You also have a wire from a terminal on either the starter solenoid or the starter motor itself, straight to the coil positive. That is so when the engine is being cranked, the coil gets full battery voltage (which will have dropped to about 10 volts because of the starter motor load). If the power only went through the ballast wire/resistor during cranking, the voltage at the coil may be too low to produce a healthy enough spark to start the engine.

The resistance wire is about 1.8 to 2Ω, and the coil primary resistance is between 1.1 and 1.5Ω. It does sound like the resistance wire has failed (engine runs while the key is held at START but dies when released to the RUN position), but you can still buy a new one from Merc. The part number is 84-94227A2... That would keep the engine as 'original' as possible. If you wanted to just replace the resistance wire with a ballast resistor, you could do that instead. Just get a normal wire and replace the resistance wire, and run that into the ballast resistor, then the coil positive. Same result. Swapping coils and distributors isn't going to help.

Chris...........

I need to give an update. Apparently I have been slacking on my communicating.

There was a problem with power in the resistance wire. After fiddling power was restored from the run side of the ignition switch. Testing both the + and - terminals on the coil have shown me that I tested the resistance circuit voltage with closed points. When the points are open I get 8v on the better running motor and only 5 on this one. It ran like crap so I am running through the tune up sequence.

I bought new plugs. I will gap them and install them tomorrow. Then onto the points.

 

[tank1949]

Yes. I intend to re-wire everything. By connectors you mean the ring terminals? Or a harness connector? I assume people replace all the harness wiring with new also right? If I replace the harness wiring is there a problem running the wires to a terminal block on the transom? Oh wait. I should make a new thread with this. Back to the tune up.

What do you mean about the coils? Make sure they are marine grade? What about the distributors, are they marine specific?

Marine grade for your specific motor. But, I believe automotive will work too, if your boat requires internal resistant coil. Any terminal., ring, spade, etc. make sure marine grade. You boat must have a marine grade or suitable distributor at that age. No space age computer stuff, unless someone before you retro-fitted it, but I doubt it. There should be a number on it or take photos and provided to these guys. They are more than knowledgeable to help.

 

[ttownthomas]

Uh. I cross referenced the original plugs (AC-CR44N) and thought the correct NGK plug was the BR6ES but these plugs are longer. Which one is correct?

 

[Scott Danforth]

I need to give an update. Apparently I have been slacking on my communicating.

There was a problem with power in the resistance wire. After fiddling power was restored from the run side of the ignition switch. Testing both the + and - terminals on the coil have shown me that I tested the resistance circuit voltage with closed points. When the points are open I get 8v on the better running motor and only 5 on this one. It ran like crap so I am running through the tune up sequence.

I bought new plugs. I will gap them and install them tomorrow. Then onto the points.

Napa has resistance wire in stock on a spool. you need about 2 feet of it. its about $3 a foot. you have to ask the old guy behind the register as anyone under 50 wont have a clue unless the guy is into hotrods and old cars.

they also have it pre-wired with terminals (about 1000% higher than simply buying from the bulk spool) https://www.napaonline.com/en/p/ECHICR22

or replace the resistance wire with a standard wire and a balast resistor for under $6 https://www.napaonline.com/en/p/BK_S43243

 

[ttownthomas]

Napa has resistance wire in stock on a spool. you need about 2 feet of it. its about $3 a foot. you have to ask the old guy behind the register as anyone under 50 wont have a clue unless the guy is into hotrods and old cars.

they also have it pre-wired with terminals (about 1000% higher than simply buying from the bulk spool) https://www.napaonline.com/en/p/ECHICR22

or replace the resistance wire with a standard wire and a balast resistor for under $6 https://www.napaonline.com/en/p/BK_S43243

So i run the resistance wire from the harness plug to the coil. I assume it is regular wire on the boat side of the harness?

 

[Scott Danforth]

its a short section of resistor wire from the factory. follow the manual schematic

Here is the service manual section on the wiring diagrams specific to your 6-banger http://boatinfo.no/lib/mercruiser/manuals/mercruiser1.html#/286. the white wire is the resistor wire shown in a dashed line
Here is the service manual section on the ignition http://boatinfo.no/lib/mercruiser/manuals/mercruiser1.html#/212
Here is the service manual section on electrical http://boatinfo.no/lib/mercruiser/manuals/mercruiser1.html#/178
Here is the service manual section on adjusting the points http://boatinfo.no/lib/mercruiser/manuals/mercruiser1.html#/38 and http://boatinfo.no/lib/mercruiser/manuals/mercruiser1.html#/230

If you do not want to run resistor wire and would like to run regular wire and a balast resistor. use 16 gauge wire (preferably purple for today's standard color scheme and a ballast resistor where the white dashed wire is shown in the schematic.

 

[ttownthomas]

Sorry to bump. Anybody have any advice on if I have the right spark plugs? See post #44

 

[ttownthomas]

NGK's website also shows a BR5FS depending on serial number of engine. The BR5FS is a tapered seat plug like the champions that came out. The other engine has the same champion plugs. My blocks have been replaced with 292 blocks so I can't tell which is correct by serial number. Does this picture of the plug hole help?

 

[tank1949]

I hate to be the deliverer of bad news, but are those motors high compression motors (for today's fuels) and do they have harden valves? Some of those older motors need lead in gas for valves. Your compression values indicate 9 to 1 ratio or lower, which is good for todays crapy fuel. A 72 boat may require lead additive in fuel or you will be having more problems later on. While you are at it, disconnect fuel line at carb (bad motor) and have a friend spin motor over. Watch and see if gas comes out freely into bucket. You may have mud dobbers nesting in gas tank air vents. Has fuel set for long? Run it several times through filter or dispose of it. Alcohol destroys rubber in fuel lines ands that rubber may be in carbs. Good luck!

 

[Scott Danforth]

I hate to be the deliverer of bad news, but are those motors high compression motors (for today's fuels) and do they have harden valves? Some of those older motors need lead in gas for valves. Your compression values indicate 9 to 1 ratio or lower, which is good for todays crapy fuel. A 72 boat may require lead additive in fuel or you will be having more problems later on. While you are at it, disconnect fuel line at carb (bad motor) and have a friend spin motor over. Watch and see if gas comes out freely into bucket. You may have mud dobbers nesting in gas tank air vents. Has fuel set for long? Run it several times through filter or dispose of it. Alcohol destroys rubber in fuel lines ands that rubber may be in carbs. Good luck!

I want what you are smoking..... the in-liner 250's are low compression, low RPM motors (8.5:1 compression and 4200 RPM max) . you sir, should really learn what you are talking about.

the motor was born with a 8.5:1 ratio, and in the mid 70's dropped to 7.7:1 in cars, yet the marine motors (GM Industrial engines) maintained the 8.5:1 ratio

it is much higher then the 216 and 235 cubic inch motor it replaced which was 6.5:1

you are now trying to argue with an Inliners.org and stovebolt.com member

 

[tank1949]

I want what you are smoking..... the in-liner 250's are low compression, low RPM motors (8.5:1 compression and 4200 RPM max) . you sir, should really learn what you are talking about.

the motor was born with a 8.5:1 ratio, and in the mid 70's dropped to 7.7:1 in cars, yet the marine motors (GM Industrial engines) maintained the 8.5:1 ratio

it is much higher then the 216 and 235 cubic inch motor it replaced which was 6.5:1

you are now trying to argue with an Inliners.org and stovebolt.com member

Don't get your panties in a wad. I am not ARGUING WITH ANYONE! I ASKED "are," since I wasn't sure and perhaps owner is not sure either. Learn how to READ! He said that he is restoring!!!! Motors look pristine and as far as I know, new ones haven't been made in some time. I started to buy an older (1973) I think year, that HAD Chevy inline 6s. It also had warnings ON VALVE COVERS that required leaded gas. If these are saltwater motors, I doubt that they are original. Perhaps rebuilds from junk yards with case hard valves? That's how I'd repower the boat. LOL

 

[achris]

The plugs you pulled were Champion RV15YC4. The 'C4' at the end just means Copper and a 40thou gap (you should always check the gap anyway)..

For engines with serial number above 2771483 (mid 1970 and later), and the correct plug is an AC-MR43-T or NGK BR5FS.

If you can find a serial number on the engines, that would helps us (and you) a lot...

Chris........

Serial number could be on this label.

 

[ttownthomas]

Boat had 250's when new. They were replaced with Jasper rebuilt 292's at some point Not sure if the heads are 292 heads or 250 heads. I took a picture of the head label but the serial number does not come out in the photo. Heads say use only leaded fuel. They are freshwater motors from lake Erie. It has non-ethanol fuel in it and there is no "old" rubber left in the fuel system. The carbs are a mess and need to be rebuilt. New A1 hose tank to pump and Copper tube pump to carb. I have to assume at this point that only 5v at the coil is contributing to the rich running problem. Can't find resistance wire locally so I'm ordering some.

 

[achris]

.. I have to assume at this point that only 5v at the coil is contributing to the rich running problem. Can't find resistance wire locally so I'm ordering some.

Same head for 250 and 292.

The low voltage at the coil + will make for a very weak spark. That's what's making the plugs look like it's rich. Likely the carb idle mixture has been fattened up to try to get the thing to fire with a weak spark, also making it look rich.

Chris.......

 

[ttownthomas]

Same head for 250 and 292.

I meant that I didn't know if the head was from the 250 or if the 292's came as long blocks so I could not trust the block number to tell me the age of the heads. Nonetheless I feel fairly confident that the tapered plug was the right one. Here are all three. Installed the AC delco plugs. Runs better but still not well. Going to pause the work until I find resistance wire online. No luck finding any yet

 

[tank1949]

Spec is 140 psi per the fsm. I thought an average of around 130 was pretty good

What you have is a labor of love and a FINE boat once bugs are gone. If not case hard valves, there are additives that you can add to fuel (if you become concerned). Be sure that you test transom for rot. I've been "burnt" before by incompetent marine surveyors. In addition, you will know your boat. You might consider retrofitting to Thunderbolt 4 or 5 ignition system, if compression is to standards and you feel are worth saving. Fresh water motors seem to last a lot longer than saltwater motors. I owned a points type distributor motor on a OMC POS stern drive back in the early 70s. MC TB 4-5 ARE DEFINATELY SUPERIOR and less headaches. I'd Google used ones on Ebay. I knew MC made them for V6s but maybe not for straight 6s. Keep asking questions! Good luck!

 

[Scott Danforth]

Boat had 250's when new. They were replaced with Jasper rebuilt 292's at some point Not sure if the heads are 292 heads or 250 heads. I took a picture of the head label but the serial number does not come out in the photo. Heads say use only leaded fuel. They are freshwater motors from lake Erie. It has non-ethanol fuel in it and there is no "old" rubber left in the fuel system. The carbs are a mess and need to be rebuilt. New A1 hose tank to pump and Copper tube pump to carb. I have to assume at this point that only 5v at the coil is contributing to the rich running problem. Can't find resistance wire locally so I'm ordering some.

Head gasket sticker says use leaded fuel because of the soft valve guides and the valve seats that were in-use in 1972. in 74, that stuff came hardened from GM.

However if you have a Jasper rebuild 292 in there, it would have come with hardened seats and guides as part of the rebuild, so the sticker on the valve cover is from the original 250

292's have a lower compression ratio than the 250, and about the same amount of torque as a 327 V8 up to about 2500 RPM

do not use copper tube in the fuel system. there are about a dozen reasons the USCG says no to copper. those lines should be either steel or A1. the primary reason is it doesnt like vibration and will crack.... then there is the whole dezincification issue

at 5V at the coil, you have a few bad electrical connections and its amazing its running at all. yes, with only 5v at the coil, you are not getting anywhere near a hot enough spark.

 

[ttownthomas]

do not use copper tube in the fuel system. there are about a dozen reasons the USCG says no to copper. those lines should be either steel or A1. the primary reason is it doesnt like vibration and will crack.... then there is the whole dezincification issue

I read the boatbuilders handbook prior to running the line and found thick wall (.032) seamless annealed tubing per the regulations. Plus it is only the fairly short run from the fuel pump to the carb. Is this not kosher?

 

[alldodge]

My opinion from reading the USCG spec, copper is ok to use between fuel tank and connection which goes to A1 line to engine (fuel filter). Boats have used copper from tank to shut off valve and all is attached to stringers and supports. Once fuel leaves stringer/valve connection it goes to flex line to motor (fuel filter). From filter it uses steel line onward.

Brake line works great for this