2005 460 - 480CE Valve Drop

TJ Nagorsen

New Member
Jun 29, 2020
8
Boat Info
2005 Sea Ray 460 DA
Engines
Cummins 6CTA 8.3 480CE
Hi all! I’m new to the group and relatively new to my 2005 Sea Ray 460 with the 8.3 480CE motors with 650 hours and a fresh water boat. Last week I unfortunately experienced the infamous 480CE valve drop in the #4 cylinder on the starboard engine. Cummins has been out and we are currently waiting on the “new and improved” head, hope it’s not too long, pretty short season in Michigan!

Can any of you 460 experts shed some light on what power settings you are using and fuel burns? I am starting to get the feeling I am way over propped. I had the wheels done last winter and currently running 27 pitch. In cruise I am seeing about 23-24 mph at 2,250 rpm and a fuel burn of about 18 GPH per side. The boat is a bit heavy with a hardtop and hydraulic platform.

Any information / data would be greatly appreciated

- TJ
 
Welcome to CSR. Sorry to hear that TJ. Hopefully they can get you back on the water ASAP.

The nationally-known Cummins expert is Tony Athens - he’ll tell you everything you need to know about your C’s. You can find him on sbmar.
 
Hey TJ

Sorry to hear your troubles, and hope Cummins can get you back up and running soon. I think you will get a lot of good information on here, but let me suggest you head over to sbmar.com and you will find a wealth of information concerning your specific engine and the things you can do to improve your engine longevity. Check out Tony's Tips and the forum.
 
You should be burning in the neighborhood of 15-15.5 gph each at 2250.
Sorry to hear about your troubles. When you get it back together, your FIRST order of business is to get re-propped. Go to the SB Marine web site the others mentioned.
Good luck, and welcome to CSR.
 
Last edited:
Whoever had all the data broken down by rpm l/hr g/hr I accidentally deleted it. First day with my new hands! Very sorry and chance you can repost?
 

Attachments

  • 6CTA 480CE [480,2600,2960,HO,Oct 02,M-90821].pdf
    115.5 KB · Views: 355
TJ,
As mentioned above by Bill and the others, pitch your props to the 6CTA curve. My mechanical motors were over-propped from the factory. WOT on the 6CTA is supposedly 2600 but Tony Athens recommends 2700 minimum. If you do that, your cruise at 2250, even 2275 will provide lots of safety, and hopefully avoid the dreaded 480CE valve drop.
I have two sets of props to play with so the set I am using this year is pitched to 25" instead of the 26" original, H cup. I get close to the recommended 2700 WOT with a total fuel burn of 26-27 gph. My other set comes from a later 460 Sundancer with your motors, the 480CE. From the factory they were set to 27" pitch. Too much! So I had these props pitched down to 25.5", less cup. You also have to consider the cupping and where the cup starts on the blade, more curved or straighter. It seems there's a lot of voodoo magic in the formula but a good prop shop will get you there. Where are you in Michigan? I used Wolverine and Johnny's.
Bottom line is to aim for less pitch/cup and achieve higher WOT, resulting in more relaxed engines at cruise. I still cruise at 20 knots with a 1/2 - 3/4 fuel load. Our 460 boats are slightly sensitive to weight.
Hope that helps and good luck with your repair. It's too nice a summer in the Great Lakes to give up time on the water.
 
TJ,
As mentioned above by Bill and the others, pitch your props to the 6CTA curve. My mechanical motors were over-propped from the factory. WOT on the 6CTA is supposedly 2600 but Tony Athens recommends 2700 minimum. If you do that, your cruise at 2250, even 2275 will provide lots of safety, and hopefully avoid the dreaded 480CE valve drop.
I have two sets of props to play with so the set I am using this year is pitched to 25" instead of the 26" original, H cup. I get close to the recommended 2700 WOT with a total fuel burn of 26-27 gph. My other set comes from a later 460 Sundancer with your motors, the 480CE. From the factory they were set to 27" pitch. Too much! So I had these props pitched down to 25.5", less cup. You also have to consider the cupping and where the cup starts on the blade, more curved or straighter. It seems there's a lot of voodoo magic in the formula but a good prop shop will get you there. Where are you in Michigan? I used Wolverine and Johnny's.
Bottom line is to aim for less pitch/cup and achieve higher WOT, resulting in more relaxed engines at cruise. I still cruise at 20 knots with a 1/2 - 3/4 fuel load. Our 460 boats are slightly sensitive to weight.
Hope that helps and good luck with your repair. It's too nice a summer in the Great Lakes to give up time on the water.
Thanks for all the information! Very much appreciated. After talking with Cummins I guess the new (not repaired) head they are going to put on is the fix for the dropped valve issue. So now the question is do I keep the 27” pitch with the new head or still pitch it down? Again thanks for the feedback. We keep the boat in Grand Haven at Keenan Marina.
 
Okay, we were in Algonac for years, on the other side of the state.
Your decision but I would be re-pitching. If it isn't convenient now, then run the boat easy and have your props scanned and re-pitched over the winter. Better to have a safety margin, in my opinion.
 
There is no easier RPM for those engines. You will be running outside of the Cummins curve at all RPMs if you do not re-pitch. You also have another engine with the original head that can drop a seat anytime unless you are replacing it too.
I bought a boat after being repaired for a dropped seat and spent time to get it dialed in correctly. The re-pitch took a little of the top end but added to the mid range performance at a fuel burn reduction of 2-3 GPH per engine!
 
There is no easier RPM for those engines. You will be running outside of the Cummins curve at all RPMs if you do not re-pitch. You also have another engine with the original head that can drop a seat anytime unless you are replacing it too.
I bought a boat after being repaired for a dropped seat and spent time to get it dialed in correctly. The re-pitch took a little of the top end but added to the mid range performance at a fuel burn reduction of 2-3 GPH per engine!
Thank you for the information. I’m definitely going to have the props done again this winter.
 
Thank you for the information. I’m definitely going to have the props done again this winter.
So did they tell you specifically what the difference is between the old and new head? I've never been able to find that out. Maybe they don't want us to know.
 
So did they tell you specifically what the difference is between the old and new head? I've never been able to find that out. Maybe they don't want us to know.
They haven’t said specifically but I will get an answer before it’s all said and done and will let all know.
 
The issue is not the valve itself but the valve seat. The seat would come off the head. The new part number fixed that. Jaws in an earlier post is spot on about the prop pitch. Factory in 2005 was 23x27. Too much. I went down to 25 inches and was slightly under propped. You should indeed follow the 450 diamond fuel curve. The 480CE is rpm limited to approx. 2680. You should be able to hit the limit when you are at your heaviest expected load. You will likely have to replace the liner, piston, etc. To save that expense on your port motor put on the new head while repairing your stbd.
 
The issue is not the valve itself but the valve seat. The seat would come off the head. The new part number fixed that. Jaws in an earlier post is spot on about the prop pitch. Factory in 2005 was 23x27. Too much. I went down to 25 inches and was slightly under propped. You should indeed follow the 450 diamond fuel curve. The 480CE is rpm limited to approx. 2680. You should be able to hit the limit when you are at your heaviest expected load. You will likely have to replace the liner, piston, etc. To save that expense on your port motor put on the new head while repairing your stbd.
Thanks a bunch. I’m planning on doing both.
 
The issue is not the valve itself but the valve seat. The seat would come off the head. The new part number fixed that. Jaws in an earlier post is spot on about the prop pitch. Factory in 2005 was 23x27. Too much. I went down to 25 inches and was slightly under propped. You should indeed follow the 450 diamond fuel curve. The 480CE is rpm limited to approx. 2680. You should be able to hit the limit when you are at your heaviest expected load. You will likely have to replace the liner, piston, etc. To save that expense on your port motor put on the new head while repairing your stbd.

I wonder why, since this is clearly something Cummings knew about and "fixed" with a new head, isn't taking care of customers with a new/updated head to fix the engineering / design flaw to begin with? Or maybe my expectations are just too high for them to admit there is/was an issue and they are taking care of their customers vs. charging them all over again for a mistake they might have made?
 
I have read where some have had luck with Cummins supplying the replacement parts. Have no first hand knowledge of that though.
 
We are back up and running. Ended up buying new props for the boat, same diameter just less pitch. The fuel burns are down significantly but we are also considerably slower, about 22MPH at 2,300rpm. We are still working with insurance company but I’m not real optimistic they are going to pay. The bill from Cummins was just under 12k. “Buy a boat, it’s fun” they say!!
 

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