thor thorsen

I have a cigarette cafe racer 35 ft 1987 mod.

My engine will not allow more than 4400 rpm when speeding, the engine should be good for 5500.
I can take it all the way up to 6000 when I have it in neutral.
in 4400 I get it up to 44 knots.

My question is if anyone here knows what is right propeller for my boat, or who to ask to find this out.
I think my props are too big so it wil not be able too reach the maximum rpm.

My engine is a mercruiser 7.4 ltr (454) 1996 mod
with some modifications to the cams and weber carburetor

i belive it`s the orginale mercruiser TRS drives on it now.

waycool marine

mine are on bravos 150 ratio 24 pitch 4 blades

PROTOTYPE28

I run 502's with TRS drives,Hydromotives props with a 25 pitch prop. They are 4 blade as well.

seafordguy

I run 4 blade 26 bravos.

I have about 575 HP most likely. 502's with small blowers on them.

What props are you running now and what HP?

PS - might want to put this in the Cigarette section so it gets some better visibility.

thor thorsen

I wil put it in the other forum also thanks

The props i have now is mirage 3 blades, not sure of the pitch or witch mirage prop i have for the moment.

The engines have about 500hp each.

thor thorsen

just checked the props and it says: mirage quicksilver 48 13245 A5 23p
3-blades

PatriYacht

Your engines must be down on power Thor. I'd have everything checked out and, if they check ok, drop down to 21 pitch.

thor thorsen

Yes i`m afraid of that

i wil shortly try to shoot the timing in top speed so i can check if the timing is correct, the vacum on the new trigger system is not hooked up with the top because there was no vacume port on the top.
also remove the water injection to the exhaust to see how the AF ratio is.

I`m not quit sure what the timing should be at top speed, but i`m afraid is to high because of the missing vacum.

Anyone know what the timing should be on this engine?
not sure wich cams it has, just that it wil rev 5500 rpm in top speed and it has a weber carburetor.

fastdonzi

Timing at 30*-32* should be good at wot (or above 3500 rpm) you should be able to spin 23's pretty good. did you just get this boat? how does it idle?