TROJAN F 25 (PROP)

MattSC · Post by **MattSC** » Sun Mar 14, 2010 10:49 pm

I have a Michigan Wheel 14 x 10"Nibral Dyna-jet with a full cup. I currently have a 330HP Crusader which replaced my old LM318. After trying several props, I ended up with the same one I ran with my 318, though opposite rotation. I'm still running a Borg Warner Velvet Drive 1:1

You would think I would be running more pitch, but the two engines have different power bands with the new engine having to reach between 4800-5200rpm compared to the 4000rpm with the 318. I cruise the same speed/rpm I did before 15-17kts depending on conditions around 2900rpm. The speed difference comes between 4000-5100rpm which I only try when making sure I'm within specs for the engine. It does jump out of the hole pretty quick and is much better on fuel.

Make sure you keep your trim tabs all the way up in a following sea, that should help.

foofer b · Post by **foofer b** » Mon Mar 15, 2010 9:04 am

My F 26 will give you a workout at the wheel in a following sea.

Paul · Post by **Paul** » Mon Mar 15, 2010 11:03 am

Like Matt stated, tabs up in a following sea but also "shovel the coal to it". In other words give it enough throttle to keep it moving faster than the following seas and it'l handle much better.

MTP · Post by **MTP** » Mon Mar 15, 2010 11:34 am

Paul wrote:Like Matt stated, tabs up in a following sea but also "shovel the coal to it". In other words give it enough throttle to keep it moving faster than the following seas and it'l handle much better.

I am sure that applies to an F32 as well

braymond · Post by **braymond** » Mon Mar 15, 2010 6:55 pm

Thanks, I'll definitely try raising the tabs. I have them set flush with the bottom and usually don't need to mess with them, so I don't, but I give that a try.

I have learned that "shoveling the coal to it" helps a lot, but I'm only seeing about 14knots at 3000rpms and that already burns about 10-11gph. It rides great at about 3300rpms and about 18knots but now I'm burning over 15gph. I'm only getting about 3800rpm max, but I think that's a carb problem.

I just had the carb rebuilt this week. It was really a mess. I should have taken a picture of it - hard to believe it was running. I am hoping that it will run and little better and burn a bit less once I get it back on. This weekend is looking good for a test run.

cclark75006 · Post by **cclark75006** » Tue Mar 16, 2010 4:10 am

Well be went out and ran the boat this past Saturday. (After full tune up)
We were full of fuel (60 gallons) and had a full load of water (30 gallons)
plus 4 big people, so I estimate our weight was as follows:

Boat 5450
Fuel 375
Water 250
People 1000 and gear
Total 7075 pounds

Here is what the GPS recorded:
2000 rpms= 9/10 mph
2500 rpms= 13/14 mph
3000 rpms= 16 mph (this is top rpm @ full throttle)

I think my engine is a bit tired, but it's running smooth and starts easy. (Merc/ford 351) Still dont know for sure if it has the 14 x 10 prop so I will just check it next time I have her out of the water. Bottom is freshly painted and clean.

Curtis

prowlersfish · Post by **prowlersfish** » Tue Mar 16, 2010 6:13 am

Curtis , are you sure the bottom is clean ? maybe the the carb is not opening fully ?your top rpm should be a lot higher

cclark75006 · Post by **cclark75006** » Tue Mar 16, 2010 7:30 am

The bottom is clean for sure, just painted a couple of months ago, on a trailer until three weeks ago. I will investigate the carb to see if it is fully opening. Thanks The engine is original, burning/leaking one quart oil in the last 15 hours of operating!

braymond · Post by **braymond** » Tue Mar 16, 2010 7:29 pm

I agree with PF. You should be seeing at least 4000rpms at WOT.

Ditto on checking the throttle linkage to the carb first. After that, do a compression and leakdown check. You can get a tester cheap or even borrow one from autozone. It's a fairly easy DIY project.

rossjo · Post by **rossjo** » Tue Mar 16, 2010 8:04 pm

MTP wrote:
Paul wrote:Like Matt stated, tabs up in a following sea but also "shovel the coal to it". In other words give it enough throttle to keep it moving faster than the following seas and it'l handle much better.
I am sure that applies to an F32 as well

Yes Sir, it does ... tabs up, throttles down.

cthattars · Post by **cthattars** » Wed Jun 22, 2011 9:09 pm

i own a 1976 f26 i use to get 17 to 18 top untill i found that the tune up they put the right plug in according to ngk but im a mopar guy and the 318 that was in the boat needed 3/4 inch reach plugs and ngk was only 3/8 inch reach the plug was firing in the cylinder head not the cylinder it self now top end is 28 gps at 3500 rpm 14X10 prop slight cup
60 gallons of fuel and water with 4 people and gear this has a full wrap windsheild and hardtop

prowlersfish · Post by **prowlersfish** » Wed Jun 22, 2011 9:26 pm

You should be closer to 4000 rpm ( clean bottom) maybe remove the cup or a little pitch

BTW I find champion the best plug for a mopar , stay away from NGK unless you have a Japanese car .

cthattars · Post by **cthattars** » Thu Jun 30, 2011 11:28 am

champion plugs is what im using the same i use my 67 cuda and 73 duster both run 340's and 4 speeds, 318 in my boat you cant hurt that engine since im here in the great lakes lake erie im taking off the bottom paint and putting on epoxy two part paint that should give me alittle more speed so i'll reprop it later for lower rpms and or more speed

kjpf25 · Post by **kjpf25** » Tue May 14, 2013 10:40 am

Just bought a '79 F-25 but have not had it over 2000 and not sure how to tell mph/knots.

Paul - SW Ontario · Post by **Paul - SW Ontario** » Tue May 14, 2013 2:32 pm

F25, Chrysler 318, 225 hp, 1:1 velvet direct drive, 14RH10 with cup....Approx. 7200lbs usually.

Brand new bottom....2 part polyurethane

On plane - 14 mph @ 2200 rpm
Cruise - 19 mph @ 2600 rpm
On it - 23 mph @ 3500 rpm
WOT - 27 mph @ 4200 rpm

The bottom made all the difference!!!!!!!

Paul

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