Kidnova

What Pure Energy said...

With the engine off and you push the stick all the way forward the choke plate may be wide open. But at speed the plate may not stay open or be able to open fully. Good idea to have someone look at this when your running fast. Your problem might just be a simple and quick fix. Might also want to check the tach. Good luck.

tienken

The head ports are rectangular... Cam was speced by Luniti with compression, intake and carb taken into consideration.. motor was bored 30 thousands over during rebuild.. No head porting at all.. the cam was moderate not to radical but required new valve springs and keepers. I can get the specs if necessary

Throttle is wide open under way.. Choke is fully open after the motor warms up and all the way open underway.. Checked all that... Vacuum is between 6 and 9 pounds at idle and 0, 1 - 2 fully open..

I was thinking I'm running to rich at full throttle + the prop is way off, maybe timing..
Top Speed 60MPH with current in favor, and 58 against according to GPS

Not selling jack jack I'm just getting started and everythings paid for..

blue thunder

What are you running for carbs? At that low of vacuum a 6.5 power valve would be open at idle. That vacuum is way low for a boat engine. Can you describe the needle movement of the vacuum gage at idle?

BT

JimV

p

Griff

What's the gear ratio of the drive?????

60mph at 4000rpms with a 20" prop??????

With a 1.5 ratio drive, it usually take a 23" prop spun close to 5000rpms to get 60mph.

tienken

I'll get all specifics of the out-drive, cam and so fourth.
I have to put the boat back in the water to get the exact reading of the vacuum.. I do remember exactly.. I do remember it fell within the tolerance of the operational Carb spec, as advised by Edelbrock. Edelbrock advised if the vacum was to low at idel it may be causing to much fuel delivery at idel because of the cam, not the case... They also advised me to check the fuel pressure which I haven't done "yet"... Carb is 750 Edelbrock..

When I purchased the boat with the old motor it had the same symptoms of running rich.. When I rebuilt the motor I replaced the holly carb and ignition.. Could it be the prop is not allowing the motor to spin up to the proper RMP and I'm dumping full throttle gas thus making the motor run rich?

Right now the motor pulls realy hard from 2000 RPM - 4000-- Luniti tec support told me the cam should pull like a train from 2000 - 5800?

FWK

what size fuel line?

cstraub69@comcast

As stated the "old motor also turned 4K". Then I would have to suspect:
1 Fuel delivery, less carb since it has been changed
2. Ignition, if you reused the same pieces
3. Drive gearing and prop size.

Don't know who you are talking to at Lunati, but Richard Woods and I have been friends for some years now..he is a good tech.

Hope this helps and good luck.

Chris

JimV

How much spring pressure on the seat? How much open pressure? Where is the cam installed at?

Jersey Tom

Could be a weak fuel pump or blocked hose/filter. Being that the problem is the same as before the engine work, I would check all parts that were not replaced, starting with the fuel system.