36' 1973 Trojan Tri-cabin Engine specs needed

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bcritical
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36' 1973 Trojan Tri-cabin Engine specs needed

Post by bcritical »

I am trying to find information on what I should expect from my Trojan

Engine are Ford 351 ie Mercruiser 255.

WOT?
Speed @ WOT?
Cruise Speed and RPM.

I only get at WOT 3300 RPM and 21MPH. I have been cruising at 2800 PRM and 16MPH. To me this seems right but the WOT seems like it should be at 4000-4200. All the normal things have been checked, bottom fresh paint clean props no knicks, little bit of vibration but not to bad. New plugs, wires, electronic ignition. Starts up quick, idles steady pulls rpm steady and easy just doesn't get to higher RPM. Am I wrong to belive that it should get to 4000, if so what should it get to?

Also the boat has quite a wander to it, in rough seas its almost to tough to handle. It will make a 40deg turn even with a full swing in opposite direction of the wheel. Even in light seas it wanders alot. Is this a common issue with these boats.
I noticed the rudders seems small for such a large boat and they also have a angle to them in relationship to the shafts. At first I thought they were bent but both are exactly the same. IS this correct?
I didn't check the toe of the rudders and if I were to what would I set them at?

Bill from Maryland
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prowlersfish
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Re: 36' 1973 Trojan Tri-cabin Engine specs needed

Post by prowlersfish »

You should see 4000-4200 rpm Not sure on the speeds of the tri . Is the bottom clean ? On the steering you could have the trim tabs too far down and or to much weight in the bow . Now if its in a following sea it could be normal .
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Re: 36' 1973 Trojan Tri-cabin Engine specs needed

Post by prowlersfish »

The toe is 2.5 deg. per rudder total of 5 deg. toe in at the front /toe out at the back . this is the rudder it self not the steering arms


do you have pics of the rudders
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Re: 36' 1973 Trojan Tri-cabin Engine specs needed

Post by rickalan35 »

Hi - I agree with Prowlerfish regarding his rudder details and also his explanation for the skittery handling qualities. If you get the throttles opened and then begin easing the tabs down, you'll reach a point where your speed and the readings on your tachometers will increase....... but on my tri, I feel that it's approx at the three quarters point of the trim tabs movement range. If my tabs are too engaged, the bow starts digging and it can be a bit scary and certainly will cut your performance. btw, my advice would be to open up the throttles with a little bit of tab-down already in place because she'll squat down pretty good if you don't. Good luck.
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Re: 36' 1973 Trojan Tri-cabin Engine specs needed

Post by rickalan35 »

In light seas, the tricabin should track relatively straight. Something is probably wrong with yours.

In heavy seas, the bow on my tricabin will be pushed to the side when hitting waves when contacting them on an angle, but every boat will do that.imo

I'm not usually out in the soup unless it's by mistake, but when it does happen I find that the tricabin's bow is easily pushed around. Tricabin's don't love idling along in a following sea either, so try to run along a little faster than the water is moving. imo
Trojan 1994 370 Express, 502 Bluewaters
bcritical
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Re: 36' 1973 Trojan Tri-cabin Engine specs needed

Post by bcritical »

SO I have not been able to find the reason for the rpm to only be at 3300. Again everything runs fine the engine are 351 Fords stock. Does anyone know where I can find the spec sheet for this boat?

I have been running at 3000 at 20knots but that seem like a bad spot to be when WOT is at 3300? How can I get these engines at 4200.

Compression is correct on both and she runs smooth.
Props are what is calle dout for in my documentation that came with the boat.
Bottom was freshly painted and cleaned.

HELP

Thanks all
Bill
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Re: 36' 1973 Trojan Tri-cabin Engine specs needed

Post by WayWeGo »

Have you checked to make sure your carb secondaries are fully open when at full throttle position? I have seen boats where the owner purposefully adjusted the throttles to keep the secondaries closed to save fuel.
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Re: 36' 1973 Trojan Tri-cabin Engine specs needed

Post by bcritical »

When I bought the boat the props on the boat were totally gone. I found what I thought was a spare prop and found another to match local salvage marina. I think this was a wrong course of action.

So if anyone with this type of boat could help me determine what the factory correct Dia and Pitch for my boat and engine. I think the prop might be to much and what the factory WOT should be to make sure i get the right prop on the vessel.

Thanks
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Re: 36' 1973 Trojan Tri-cabin Engine specs needed

Post by bcritical »

WayWeGo wrote:Have you checked to make sure your carb secondaries are fully open when at full throttle position? I have seen boats where the owner purposefully adjusted the throttles to keep the secondaries closed to save fuel.
no problem getting to 6K and secondary opening out of gear. I also can see the secondaries open during WOT underway but make RPM is 3300 at 23mph
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Re: 36' 1973 Trojan Tri-cabin Engine specs needed

Post by Allen Sr »

I am surprised nobody brought this up but is your mechanical advances on your distributors working good? Just my 2cents worth. If your not getting the full advance you will lose rpms that way.
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Re: 36' 1973 Trojan Tri-cabin Engine specs needed

Post by prowlersfish »

You maybe over propped , Not sure what the top speed should be with the 351 mercs most the early tris I have seen have been 400cid (280 hp)


I found my prop list for 1976 Trojans and it calls for 20X21 no cup 3 blade props both for the 351 merc and the 400 Chrysler . In real life factory props tend to be on the large size (over propped) as we load our gear the boat get heavier . the factory was only interested in top speeds with a light boat . This was for sales reasons (speed sells )


What props are you running now ?
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