Repower

[Seafighter]

I thought I would start a new thread with Cuz's last past... "I have a 1976 '35 and installed 370 Cummins in 2001 . Boat has a cruise of 24 kts at 2600 rpm and 26-27 kts at 2800 rpm and 30 kts at wot 3000 rpm. We did not have to raise the saloon floor . Thanks Randy" Randy, Can you give me some fuel burn figures at those rpms? Was yours a diesel to diesel install? What did you pull out? What else did you replace? Do you have a ball park figure on the cost? Any info would be appreciated.

[JohnD]

Good Thread! The one think I'd like a little more info on is fuel burn at 20-22kt cruise. For my gas B35, a 1972, I've found that I get about .65 or so mpg (miles per gallon). The data based on my trip from Baltimore MD to Atlantic City this summer. Fuel quality issues aside, I really like my gas motors. They run well, we ran 9.5 hours from Atlantic City to Baltimore comming home from the rendezvous with only an hour layover in Cape May for Lunch and fuel. With 3208's I believe the burn is somewhere around 1.0 to 1.2 mpg which is about double mine. I'd think the cummins would be the same or better. John

[Cuz We Can]

We burn about 20 gals an hour at 2600 rpm. Our boat had 454's, when we installed the 370 Cummins we replaced shafts (1 3/4)struts, 21x21 four blade props, new fuel lines, sea water strainers , installed racors, new 6 inch exhaust and a new Next Gen 5 kw genset . Adds up to about 1 mile per gal. Thanks Randy

[Seafighter]

Randy, Can you tell me what gears you are using?

[Cuz We Can]

Seafighter we are running ZF marine IRM 220 1.5 ratio. Thanks

[michael]

Randy I have the same set up 370bs with the same gear as you.I am not sure of the prop size but both engines top out at 3000rpm.I have a 1979 33SF.I do not get the speed you do.At 2400rpm I do 19 knots,2600-21to 22 knots and wide open I do 25 knots.What do you carry for fuel.I put my generator forward of the engines under the cabin floor.I added a 100 gallon fuel tank back where the generator would normally be.I now carry 400 gallons of fuel.I was concerned about the weight but the boat goes up on plane with no problem and if I want I can push the bow way down with the tabs.I am beginning to think I need to get rid of all the bottom paint and start with new. Michael

[dougl33]

Michael, I'm surprised by your numbers. I know Charlie haws has the 300hp 3208's in his 1984 35 and he gets better numbers than that. I think he's cruising around 21-23 knots and topping out around 27-28 knots. Hopefully he'll chime in. Regards, Doug L. 1986 33 Bertram FBC Queen Elizabeth Marblehead, MA [img]http://www.bertram33.com/photogallery/p ... sabeth.jpg[/img]

[CB35]

I do have a 1984 3208 300HP Cat 35B. At last haul she weighed 24,900 pounds. When I am light I do 20-23 kts at 2400RPM's. Add people, fuel, water and gear and she goes over 28,000 pounds. At that weight I get 18-20 kts depending on sea conditions. You should be at least 1000 pounds lighter with Cummins. Then add back in the exter fuel. While you turn up to 3000 with the cummins I think your props mat be to blame. I turn a 20X22 three blade Nibral with a 6 cup on a TD 506 1.5:1 tranny. I have the original owners book and my original 1984 35B still makes the book numbers. I have spoken to a number of guys who turn 4 blade props and none of them come close to the factory numbers. I bet you are running 4 blades? Charlie

[JohnD]

In considering the repower with Cummins 330's I've received the following reccomendation: 6BTA 330's ZF 220A 1.75:1 tranny 1.5" shafts 21x22 4-blad props should be good for a 22-24 kt cruise c'mon MegaMillions or at least MiniMillions John John D "Lady D" Bertram 35 Pasadena MD

[CB35]

John if you want to slow the boat down for stiper trolling you may want 1.5:1 gears. If all I did was run offshore and troll tuna I would want 2:1 gears. If you want to go slow you will need 1.5:1 and run on one motor. I can get my 35B slowed to 2.5-3.5 kts. Into the wind I can get her down to 1.5Kts. Them stripers love those bunker spoons. I hope to have my boat back together by the middle of the week. This weekend is going to get blown out anyway. 3208 Head gasket failure. Charlie Charlie

[JohnD]

You're probably right about the 1.5:1, just have to live with a little less cruise speed. With my gassers I can get down to 1kt on one motor pretty easy. When I first got my boat the idle was set up to 1k rpms and when docking I'd toss people around while shifting in and out of gear, no fun. I thought it was intersting that Wes felt the 1.75:1 was the way to go. He said if he had to do it over again he'd go with the those over the 1.5:1 hands down. Now that's a pretty good reccomendation I have a great deal on some 2:1's but that would be a little too much and not allow the motors to turn up the way they should. Also puts more stress on the running gear and I hope not to go more than 1.5" shafts. Down here in the bay lots of guys drag buckets or what have you to get down to rockfish speed. Good luck on getting your motor back together and up and running. I think the season's probably over for me. Too many barnicles on my running gear and I don't want to spring for a short haul. I'll probably pull mid nov. Tis the season for Birthdays and Holiday's in my family. I'm getting closer to pulling the trigger on some diesels. Then just tonight the upstairs shower decides to leak through into the kitchen... When it Rains it Poors... With any luck maybe I can have the newest cummins repower at AC next year or the year after that or the year after that... br, John John D "Lady D" Bertram 35 Pasadena MD

[CB35]

If all I did was troll for tuna then 2:1. You know you may not have room between the wheels and the hull for a 2:1 on a 370 HP cummins, The original 555 210HP cummins turned 1.97:1 with a 22X22 wheel. My 300HP Cat turns a 20X22 wheel. I did believe a 1.75:1 would be great choice. Charlie