Official 390 E.C. Thread

Hey guys...I have lightly searched for information on oil changes, but cannot find anything for our boat specifically. My boat has 7.4 gassers. What is the oil capacity? What oil are you guys running? Any particular brand of oil filter or fuel/water seperator that is preferred? I thank you in advance for any information.
 
You're oil capacity should be 6 quarts with filter. To be safe put in 5, run the engine for a minute, shut down and check level. Add another quart if needed. You're old flat tappet engines require oil with ZDDP additive to protect the camshaft and lifters. I use Valvoline VR1 racing oil it is available in different "weights". I use K&N oil filters because they have a heavy duty shell and quality internal components. I installed Racor fuel filters when I got my boat 9 years ago. Make sure you get the "inboard" engine Racors with the metal fuel bowl.
 
Your best cruise rpm will depend on whether or not your boat has had the typical 390EC trim tab modification that has been discussed many time in this thread. The purpose of the modification is to get the bow of the boat "over the hump" to obtain good visibility and have the boat run at the best "attitude" which results in the best ride and efficiency. I have made the extensive modifications to my trim tab system and my 390 will come up on plane with full fuel and up to 10 adults on board at 2800 rpm and about 20 mph.

As far as mpg don't expect anything spectacular. Once you pass hull speed "aprox. 8mph" you will get aprox. .6mpg. It doesn't matter if you are going 12mph or 25mph those 454s will net you about .6mpg. I know this because I have Garmin GFS10 flow meters. At 6-7 mph that will improve to aprox. 1-1.1 mpg. Stop judging your boat and usage based on mpg. The cost of fuel is one of the cheapest parts of your boat ownership.
 
I just purchased a 1989 Sea Ray 39 EC with Twin Caterpillar 3208 TA’s. It’s been sitting on a lift and I need info before I proceed. I need to re-pack the prop shaft stuffing box. What size is the packing? I also need to replace the cutlass bearings and need to know there size. I have not been able to find this info. Since I can’t get to the boat daily, I have to get my supplies and drive to her to work. It’s a long ride!
 
I seem to recall that it takes 1/4" packing. As for the cutlass bearings, mine are 1-1/2" ID (shaft size) X 1-3/4" OD X 6" long. There are 10 flutes in the bearing.
I have a 1988 390EC with the 3208 Cats. Running 20 X 25 NiBrAl props.
Awesome boat. Welcome to the party!
 
Thanks! I finally found this online! The 390 I purchased has been sitting in a sling on the intracoastal for a while. She only has 512 hours on her engine. I'm going to fix a lot of regular maintenance items on her before I drive her back up the TennTom waterway to the Tennessee River. Cosmetically she is beautiful, and barely used. I want to change the Cutlass Bearings, oil, etc.
Can you possibly give me any guidance on the transmissions? The port transmission spins slowly when in neutral! Could this be a low fluid problem? If so, what type fluid do these transmissions use?
I sure hope anyone here doesn't mind me asking a lot over the next few months! My last large boat was a Chris Craft 320 Amerosport and I did all my on work. This is much different because of the diesel engines and size. I'm adjusting well so far! Thanks to you!!!!
 
My last 2 boats have had Borg Warner Velvet Drive transmissions. On each boat one of the transmissions has had the prop shaft spin slowly when cold in neutral. The spinning stops when it warms up a little. The problem is the forward clutch pack is shimmed a little too tight and drags just slightly when cold. It is a minor problem that really doesn't bother me so I left them alone. If it continued after warm up I would have removed a rebuilt the transmission.
 
hottoddie said:
My last 2 boats have had Borg Warner Velvet Drive transmissions. On each boat one of the transmissions has had the prop shaft spin slowly when cold in neutral. The spinning stops when it warms up a little. The problem is the forward clutch pack is shimmed a little too tight and drags just slightly when cold. It is a minor problem that really doesn't bother me so I left them alone. If it continued after warm up I would have removed a rebuilt the transmission.
Click to expand...
Thanks.....Still learning on this boat. I'll check fluid levels and then run her and check after I get them warmed up.
 
Greetings!

This is a lonnnng overdue thank you to all of the members here who shared their knowledge over the years with the group. I fell in love with the 390 a few years ago, for the classic styling, the roominess (I'm tall), and the sheer value. I painstakingly read EVERY post in this forum - and took many sidetrips to other sites after learning of them here - and the wealth of information was instrumental in finding the right boat for me and for my family. I purchased ours in the Spring of 2019 and have been enjoying her ever since. I cannot tell you how often I returned to bookmarked posts to re-read content that I KNEW would come in handy one day.

Finally, it seems to me that the apparent exodus to facebook was a turn for the worse, content-wise, and hold out hope that this forum will someday return to it's former level of activity. I'll be around.

Thank you all again.
 
hottoddie said:
My last 2 boats have had Borg Warner Velvet Drive transmissions. On each boat one of the transmissions has had the prop shaft spin slowly when cold in neutral. The spinning stops when it warms up a little. The problem is the forward clutch pack is shimmed a little too tight and drags just slightly when cold. It is a minor problem that really doesn't bother me so I left them alone. If it continued after warm up I would have removed a rebuilt the transmission.
Click to expand...
 
I noticed that it stops when the temperature is warmer. Even after just idling for 5 minutes when cold it stops. Going to do all impellers next.
 
Mer-Sea Monster said:
I seem to recall that it takes 1/4" packing. As for the cutlass bearings, mine are 1-1/2" ID (shaft size) X 1-3/4" OD X 6" long. There are 10 flutes in the bearing.
I have a 1988 390EC with the 3208 Cats. Running 20 X 25 NiBrAl props.
Awesome boat. Welcome to the party!
Click to expand...
 
Thanks for the info! It was perfect. Used the new Golo packing. No drips at all now! Do you know where the air compressor for the air horn is located? Keeps tripping the breaker!
 
Yes on the air compressor suggestion , pull the hose off and let some oil run down into the pump area and sit for a while, then give it a try.
 
MOzarkian said:
Greetings!



Finally, it seems to me that the apparent exodus to facebook was a turn for the worse, content-wise, and hold out hope that this forum will someday return to it's former level of activity. I'll be around.

Thank you all again.
Click to expand...
This was a very good forum until everyone went to Facebook like you said I hope it returns to what it was previous.
 
Anyone know what size shaft packing I need and what length per side?
 
You must log in or register to reply here.

Forum statistics

Threads
113,163
Messages
1,427,604
Members
61,073
Latest member
kolak3
Back
Top