Re jetting quadrajet carb
04-25-2019, 12:50 PM
#21
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Bump it to 20* initial (idle) ......but DO NOT drive the boat like that since that will likely be overtimed once the centrifugal advance kicks in....this is simply seeing what it wants for idle timing.
You will likely need to reduce the amount of centrifugal advance so you can run more initial and not overtime the engine while running at higher RPM under load.
What is your total timing now?
You will likely need to reduce the amount of centrifugal advance so you can run more initial and not overtime the engine while running at higher RPM under load.
What is your total timing now?
04-25-2019, 01:21 PM
#23
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Also, as suggested previously...you will want a wide band AFR gauge for tuning.
This manifold adapter may work for you.
https://www.cpperformance.com/p-1043...SABEgKdxfD_BwE
This manifold adapter may work for you.
https://www.cpperformance.com/p-1043...SABEgKdxfD_BwE
04-25-2019, 01:24 PM
#24
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I can’t stress the wideband enough myself. My boat ran great but the wideband showed a lean spot right at peak torque at my cruising speed. You’ll also save days of headache on the lake trying to dial in the carbs.
04-25-2019, 01:35 PM
#25
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widebands almost make me feel like im cheating...lol
Every single IC engine toy I have either has a wideband on it or has a provision for me to hookup one of my handheld widebands.
Since you have changed the configuration of the engines you will need to change the calibration.
I would consider a wideband a requirement since you have modified the engines.
Every single IC engine toy I have either has a wideband on it or has a provision for me to hookup one of my handheld widebands.
Since you have changed the configuration of the engines you will need to change the calibration.
I would consider a wideband a requirement since you have modified the engines.
04-25-2019, 10:00 PM
#27
Bump it to 20* initial (idle) ......but DO NOT drive the boat like that since that will likely be overtimed once the centrifugal advance kicks in....this is simply seeing what it wants for idle timing.
You will likely need to reduce the amount of centrifugal advance so you can run more initial and not overtime the engine while running at higher RPM under load.
What is your total timing now?
You will likely need to reduce the amount of centrifugal advance so you can run more initial and not overtime the engine while running at higher RPM under load.
What is your total timing now?
04-26-2019, 03:30 AM
#29
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Now that you have idle you can keep on figuring it out. See if it will idle with less timing because 35 degrees at full advance is a little on the iffy side. But if you think you will run it that way give it premium fuel to fight off detonation. What ignition is in there? Can it be adjusted for less advance all in?
Also SB alluded to possible reversion. I see you have the low rise exhaust risers. After an idle period remove them and inspect inside the exhaust for water. If you find water you will have to change to a higher riser. And you might want to just do it any way.
And be sure your exhaust has functioning flappers on the ends to reduce the same water incursion. I did not and have been battling reversion with a bigger cam.
Also SB alluded to possible reversion. I see you have the low rise exhaust risers. After an idle period remove them and inspect inside the exhaust for water. If you find water you will have to change to a higher riser. And you might want to just do it any way.
And be sure your exhaust has functioning flappers on the ends to reduce the same water incursion. I did not and have been battling reversion with a bigger cam.
Last edited by NHGuy; 04-26-2019 at 03:39 AM.
04-29-2019, 10:32 AM
#30
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If the heads are the newer style vortec they need a lot less timing. You'll need to limit your mechanical advance to 10 degrees.
