79 trojan 30 express

[antlr-king]

Hi havnt been on the site in a while. I'm wondering how many rpms should I be getting out of twin Chrysler 318"s. these are remans with 54 hours on them. most of that time was spent at the docks. I heard I should get 4000 rpms. but I can only get around 3000. could this be a prop issue? if so, what is the pitch on the props should I be running with this boat? we just spent around 2.5 years on and off getting this project together. shes in the water but not preforming as she should. any help would be appreciated. thanks..

[prowlersfish]

Start with a clean bottom and running gear . 4000 is good number you should shoot for .

[captainmaniac]

Typically top end is about 4200rpm. As Paul says, if you have been sitting in the water for a couple of years you probably have a lot of growth and that can have a huge impact.

I assume you are running twins. Are both engines running the same or is one worse than the other? Do you advance the throttles the same amount to hit your 3000rpm on each engine, or are the throttles way off? Have you tried hooking up a separate tachometer to find out if your gauges are reading correctly and you really are only getting 3000?

[lawyerdave71]

Mine tops out at 3400 - but I suspect there is an issue with gauges.

[antlr-king]

we move the throttles forward about the same time. the bottom and running gear are cleaned. these engines have ran this way since day 1 first launch. we have been in the water since. but have done a short haul to clean the bottom on may 1st since launch. but since we got the boat, added the 2 remans we just cant seem to get the power out of the 2 engines as we should. maybe I will get a separate tach and hook it up to see if the built in tachs are the same. I guess the props wouldn't have anything to do with it? does anyone know what the standard props should be for this boat? thanks

[mikeandanne]

Check to see if you are actually getting wide open throttle--- with the engines off,push the throttles full open then look down the carbs to see if the plates are vertical---- Mike

[prowlersfish]

we move the throttles forward about the same time. the bottom and running gear are cleaned. these engines have ran this way since day 1 first launch. we have been in the water since. but have done a short haul to clean the bottom on may 1st since launch. but since we got the boat, added the 2 remans we just cant seem to get the power out of the 2 engines as we should. maybe I will get a separate tach and hook it up to see if the built in tachs are the same. I guess the props wouldn't have anything to do with it? does anyone know what the standard props should be for this boat? thanks

The props would have a lot to do with it . What size are you running ? I can't remeber what size my F30 was .

[larryeddington]

I had exactly the same 3000 indicated on my f28 with old engines and 20 mph tops. One engine went south so am gettin two new Jasper engines installed, as we speak, may be done this week. When boat pulled the bottom only had small amount of stuff there, virtually clean.

The tech says we should and will get 4000 out of her at WOT. We shall see. Right now my tilt is toward tired used up engines. 2nd opinion is the AFB carbies were only opening on primary venturas and secondary not opening. Again we shall see soon.

[lawyerdave71]

Instead of talking RPMs and such . . . what speeds are you obtaining?

78 Manual says WOT is at 4000 which would be 32 mph and uses 40.5 GPH.

Highest I have ever been was 28 mph (according to GPS) which is fast enough for me plus she burns a ton of fuel at that speed!

[lawyerdave71]

Oh, original prop size for the F-30 is 14x11.

[Paul - SW Ontario]

we move the throttles forward about the same time. the bottom and running gear are cleaned. these engines have ran this way since day 1 first launch. we have been in the water since. but have done a short haul to clean the bottom on may 1st since launch. but since we got the boat, added the 2 remans we just cant seem to get the power out of the 2 engines as we should. maybe I will get a separate tach and hook it up to see if the built in tachs are the same. I guess the props wouldn't have anything to do with it? does anyone know what the standard props should be for this boat? thanks

Any luck with getting to WOT?

[larryeddington]

My F28 has I believe 14/11 cupped props on it now, but not sure as put the ones from my scrapped f28 and I did not record size, but same problem, props on her now are slightly slower at 18mph GPS and 2900 RPM at WOT. The prop shop says they can got 2 inches each way on pitch. I may try that reducing to 14/9 my tech thinks that is the problem. In other words needs to be geared lower.