Hey Rick,
Cam is comp cam 08-466-8, installed right at 109?ILC, it has a LSA of 113?. I pull 16 inches of vacuum at 750 rpm idle.
https://youtu.be/Fld5DCM9GlQ
Intake valve on #3 "tuliped" twice. The valve got longer overall, so a true tulip. After doing more research mostly at the Offshore Only, too much timing in the Vortec heads will tulip intake valves. As you know, turning the distributor on the MEFI4 system doesn't change timing, it changes a parameter called cam-retard. It was set with a Rinda scan tool (mine) to 45-47?.
AZSM was made well aware of the cam intended to be used, as well as my heads. I just had it with not being able to tune the thing myself without further investing in software. (and not having any confidence in the guy tuning it)
She's now a solid 60 mph boat. It turns a volvo DP with F7 props to about 5100 rpm. I burned about 50 gallons of fuel this weekend at the Chesapeake I romped on her pretty hard. Harassed a 26-28' Donzi with a NA 454 in it and out pulled him by about 2-3 mph on top end. I'm confident my problem is behind me. I can tell I'm pushing the design limits of the hull.
In the previous post, I mentioned I was still chasing perfection with jetting, I did change the secondaries to .113 and she liked it. Did a WOT run for about 40 secs and pulled the plugs, look good. This has moved me 2 "stages" richer in the "power mode staging" and 2 sizes richer in the secondaries. Jetting is real close now, real strong out of the hole, but still a tiny flat spot climbing through 3500.
I think the flat spot is once the accel pump shot is over and right before the secondaries come into full play. I may try one more size up in the power mode staging circuit. I'm thinking a .116 primary jet with a .075 x .042 metering rod. This should yield 1.33% increase in surface area with rods down, and 10.72% increase when the rods up compared to stock jetting of the 1410. (With a .113 jet and .070 x .037 metering rod I'm at 1.82% richer rods down, and 7.95% rods up compared to base)
I'm confident my problem is licked. However realizing how much richer the carb settings are from baseline, the more it makes me think the stock manifold and injectors had no chance to keep up.
I've been using this chart to contemplate jetting changes.
Jet | Primary Jet Area | Rod dia down | Area rod down | Rod dia up | Area rodup | Jet area rod down | % change from stock | Jet area rod up | % change from stock | |
0.113 | 0.01003 | 0.071 | 0.00396 | 0.047 | 0.00173 | 0.00607 | 0 | 0.00829 | 0 | Stock Calibration |
0.113 | 0.01003 | 0.070 | 0.00385 | 0.042 | 0.00139 | 0.00618 | 1.82% | 0.00864 | 4.21% | Option #2 |
0.113 | 0.01003 | 0.070 | 0.00385 | 0.037 | 0.00108 | 0.00618 | 1.82% | 0.00895 | 7.95% | Option #3 |
0.116 | 0.01057 | 0.073 | 0.00419 | 0.042 | 0.00139 | 0.00638 | 5.16% | 0.00918 | 10.72% | Option #4 |
0.116 | 0.01057 | 0.073 | 0.00419 | 0.037 | 0.00108 | 0.00638 | 5.16% | 0.00949 | 14.46% | |
0.116 | 0.01057 | 0.075 | 0.00442 | 0.042 | 0.00139 | 0.00615 | 1.33% | 0.00918 | 10.72% | |
0.116 | 0.01057 | 0.075 | 0.00442 | 0.037 | 0.00108 | 0.00615 | 1.33% | 0.00949 | 14.46% | |
0.116 | 0.01057 | 0.073 | 0.00419 | 0.047 | 0.00173 | 0.00638 | 5.16% | 0.00883 | 6.51% | Option #10 |
0.116 | 0.01057 | 0.075 | 0.00442 | 0.042 | 0.00139 | 0.00615 | 1.33% | 0.00918 | 10.72% | |
0.116 | 0.01057 | 0.075 | 0.00442 | 0.042 | 0.00139 | 0.00615 | 1.33% | 0.00918 | 10.72% | |
Secondary jet change | | | | | | | | | | |