Not able to reach top end on F32

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oil&water
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Not able to reach top end on F32

Post by oil&water » Wed Jun 13, 2018 1:11 pm

My 1980 Trojan F32 with twin Chrysler M360 is not reaching anywhere near top end. The maximum RPMs I have been able to achieve is 3,190 on both engines. Max speed was 20.2 knots with about 200 gallons of fuel onboard and no water. Just painted the bottom and all running gear is in good shape.

Is anyone experiencing similar problems?
1980 Trojan F32 / 323 (sans lower helm - wet bar in its place)
Twin Chrysler M360 / Onan 6.5

mikeandanne
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Re: Not able to reach top end on F32

Post by mikeandanne » Wed Jun 13, 2018 1:16 pm

Did you happen to see the size on your props ? Both engines sound the same ?
78 F 32

oil&water
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Re: Not able to reach top end on F32

Post by oil&water » Wed Jun 13, 2018 1:31 pm

Unfortunately, I didn’t get a chance to pull off the props before I launched it back into the water last week. I will check this weekend to see if my paperwork shows anything.
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1980 Trojan F32 / 323 (sans lower helm - wet bar in its place)
Twin Chrysler M360 / Onan 6.5

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captainmaniac
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Re: Not able to reach top end on F32

Post by captainmaniac » Wed Jun 13, 2018 6:25 pm

The speed is about right for those RPMs (at least what I get with my 16x16 cupped props), so probably not a case of drag and you likely have the right props if you match the normal speed curve.

Start with the easy stuff first... Are throttle detents or cable length keeping you from pushing to true full wide open? Are distributors properly advancing as RPMs climb? Do the engines sound or feel bogged down or do they seem to be running well? Any plugged tank vents?

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prowlersfish
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Re: Not able to reach top end on F32

Post by prowlersfish » Wed Jun 13, 2018 6:27 pm

Would be good to know the prop size . Check you tachs ( I have a photo tach you can use) . make sure the 4 barrels are opening and the carb linkage for full travel . try using the trim tabs too. Knocking off some pitch can help get the engine up in its power band and get more rpm and speed at wot .
TROJAN F36 Conv.
6BTA Cummins diesels
Life is to short for a ugly boat :D
2009 TROJAN RENDEZVOUS
Port Kinsale 2010 & 2011. Solomons get together 2011.

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WayWeGo
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Re: Not able to reach top end on F32

Post by WayWeGo » Wed Jun 13, 2018 10:10 pm

Also might be worth taking compression or doing a leakdown test to see if the basic engine is at or near spec. All the other advice above is spot on.

Our boat did not hit target RPM on the survey. Turned out that the carbs were not opening all the way.
1975 F-36 Convertible
Twin Chrysler 440's

oil&water
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Re: Not able to reach top end on F32

Post by oil&water » Wed Jun 13, 2018 11:18 pm

I spoke with Beacon Bob today and will be taking compression readings this weekend.

I did not realize the Trojan based their cruise figures on 3,000 RPMs even though they would stay on plane in the 2,600 RPM range. That being the case, I am SO looking forward to stomping this problem out so that I can fully enjoy the wider throttle band.
1980 Trojan F32 / 323 (sans lower helm - wet bar in its place)
Twin Chrysler M360 / Onan 6.5

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prowlersfish
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Re: Not able to reach top end on F32

Post by prowlersfish » Thu Jun 14, 2018 6:42 am

Hope the numbers are good and its some thing easier (and cheap ). One reason I said reducing pitch a liltle , it helps engines that are tired and boats that are hevier ( the way we add stuff) hit the needed rpm . Trojan and others propped their boats with fresh engines and light on toys and oh ya real gas :( .
TROJAN F36 Conv.
6BTA Cummins diesels
Life is to short for a ugly boat :D
2009 TROJAN RENDEZVOUS
Port Kinsale 2010 & 2011. Solomons get together 2011.

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WayWeGo
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Re: Not able to reach top end on F32

Post by WayWeGo » Thu Jun 14, 2018 8:12 pm

That may explain those small wheels I have...
1975 F-36 Convertible
Twin Chrysler 440's

oil&water
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Re: Not able to reach top end on F32

Post by oil&water » Sun Jun 17, 2018 11:27 pm

Well I didn’t get a chance to check compression this weekend. Too many other projects, like pulling a stern tank that had a broken weld. That one wasn’t in the works for sure!

I was able to get up to 3280 on port and 3375 on starboard. Going to keep working with her to see where I get.
1980 Trojan F32 / 323 (sans lower helm - wet bar in its place)
Twin Chrysler M360 / Onan 6.5

hammerhead
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Re: Not able to reach top end on F32

Post by hammerhead » Fri Jul 13, 2018 8:13 am

my buddies F30 is having the trouble. i touched on it in another thread. top rpm on both engines is 2100 rpms. it has 225's in it. we checked all throttle linkages but they seemed fine. top speed 22 mph

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prowlersfish
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Re: Not able to reach top end on F32

Post by prowlersfish » Fri Jul 13, 2018 3:24 pm

I beleave I posted this before , 22 mph seems fast at only 2100 rpm so first what props do you have and have you checked the tachs ?
TROJAN F36 Conv.
6BTA Cummins diesels
Life is to short for a ugly boat :D
2009 TROJAN RENDEZVOUS
Port Kinsale 2010 & 2011. Solomons get together 2011.

hammerhead
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Re: Not able to reach top end on F32

Post by hammerhead » Fri Jul 13, 2018 4:12 pm

he is having someone check the tachs but he just bought the boat and has no idea on the props. kinda wondering if the 4 barrels are opening up all the way

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prowlersfish
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Re: Not able to reach top end on F32

Post by prowlersfish » Fri Jul 13, 2018 10:41 pm

hammerhead wrote:
Fri Jul 13, 2018 4:12 pm
he is having someone check the tachs but he just bought the boat and has no idea on the props. kinda wondering if the 4 barrels are opening up all the way
Possible . I assume he did not haul it and get a survey ?
TROJAN F36 Conv.
6BTA Cummins diesels
Life is to short for a ugly boat :D
2009 TROJAN RENDEZVOUS
Port Kinsale 2010 & 2011. Solomons get together 2011.

hammerhead
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Re: Not able to reach top end on F32

Post by hammerhead » Sun Jul 15, 2018 6:48 am

no be bought it from a guy at the same marina he is in now

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