timing day
Thread Starter
On The Tree
Joined: Nov 2010
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From: carlsbad
timing day ok so today is my first time programming with a computer. i wanna get my timing setup at a good starting point so then i can mess with the carb.
dished piston 5.3
stock cam
brand new stock holley 750 (factory settings)
any pointers?
dished piston 5.3
stock cam
brand new stock holley 750 (factory settings)
any pointers?
So far my 5.3 with a cam likes 33* it seems, so i say you should start at 30 and go up a couple degs at a time till you feel the motor is pretty happy, you wont be able to dial it in till you get track or dyno time, but setting it at 32 and letting it go will do fine if you dont want to spend much time with it.
You have a vac sec or mechanical sec 750?
You have a vac sec or mechanical sec 750?
Thread Starter
On The Tree
Joined: Nov 2010
Posts: 169
Likes: 5
From: carlsbad
So far my 5.3 with a cam likes 33* it seems, so i say you should start at 30 and go up a couple degs at a time till you feel the motor is pretty happy, you wont be able to dial it in till you get track or dyno time, but setting it at 32 and letting it go will do fine if you dont want to spend much time with it.
You have a vac sec or mechanical sec 750?
You have a vac sec or mechanical sec 750?
Thread Starter
On The Tree
Joined: Nov 2010
Posts: 169
Likes: 5
From: carlsbad
Ok so I finally was able to get the computer connected to do my timing but I'm doing something wrong. I got the plot to send to the msd but I need to figure out this map curve so I can set the idle on my carb.
What do these things like to idle at?
And my oil pressure is 30, is that normal? My old abc used to have 60-80 psi oil pressure.
Since I'm essentially gonna be in "first gear" all the time I set my rev limiter on launch up to 6k I think. What's the safe rev limit for these motors? If anyone can chime in on my settings I'd appreciate it. The map sensor I'm using is the stock one so I believe it's a 1 bar.
What do these things like to idle at?
And my oil pressure is 30, is that normal? My old abc used to have 60-80 psi oil pressure.
Since I'm essentially gonna be in "first gear" all the time I set my rev limiter on launch up to 6k I think. What's the safe rev limit for these motors? If anyone can chime in on my settings I'd appreciate it. The map sensor I'm using is the stock one so I believe it's a 1 bar.
A safe operating range is 6500, but for the daring like myself and others 7000, but that is street and race rides that see that RPM and then shift.
No map sensor used on either of mine.
No map sensor used on either of mine.
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I don't think you'll want the MAP on a boat, the engine is under a lot more load than a car. Idle depends on cam, usually around 800, but high enough so it doesn't stall when put in "gear". Also, 30# seems a little low, my LS-1 has 60 cold and 50 hot at idle...
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On The Tree
Joined: Nov 2010
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From: carlsbad
Well I tried the suggested curve and disabled the map. Engine wasn't even able to start and got incredibly flooded. This weekend I ran the boat for the first time just using the #1 then #2 pills. It ran great but I want to do a custom curve now.
Thread Starter
On The Tree
Joined: Nov 2010
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From: carlsbad
Running the boat on pills and seeing the speed I am getting has me wanting to officially time and tune this thing. Does anyone have any 5.3 timing curves they are willing to share?
Map will be disabled.
Map will be disabled.
That's a tough call, a boat engine is under a lot more load than a car, so what works for one may not even be close for the other. I'd say try having all your advance in by 2800 - 3000. Maybe put a slight dip in the curve wherever your torque peak is to lessen any chance of det. I'd think your "planing" speed would be akin to a car's 60ft time in respect to tuning...
Thread Starter
On The Tree
Joined: Nov 2010
Posts: 169
Likes: 5
From: carlsbad
That's a tough call, a boat engine is under a lot more load than a car, so what works for one may not even be close for the other. I'd say try having all your advance in by 2800 - 3000. Maybe put a slight dip in the curve wherever your torque peak is to lessen any chance of det. I'd think your "planing" speed would be akin to a car's 60ft time in respect to tuning...
I'd like to get my timing setup so I can start messing with the carb. I do have the off idle stumble when I punch it. I also have a WOT bog, which I may think is a lean bog.
I am topping out at 5200 RPMS before it will bog.
Launching!
Joined: Aug 2010
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You really don't need the map with a jet boat. Your manifold vacum is directly elated to your rpm. It sounds like you don't have enough timing on top end. Your intial start should be low like 6or 8 deg up to 500 rpm then move it up to 18-20 by 100 rpm. then just ramp it up to 30-34 at 3000 rmp then slowly bring it back down to 29-30 by 4200 rpm. Not real agrressive but it is safe. In a jet boat you cannot get away with as much timing as a car. The ct525 engine will tolerate above 30 in a car but will explode at 29 in a jet boat. Don't ask me how I know.
