Track warrior 650cfm tuning

[twb119]

This is on a airboat LS1 346 with 241 casting heads 10-1 compression i think, I don’t remember the cam specs the motor is 12 years old with a little over 800 hours with single plane intake.
Did have 700cfm 4778-5 on it, it was getting a little tired and replaced it with Holley Track warrior 650cfm #67199 and very happy with so far very good throttle response and picked up 200rpm at WOT over the 4778.
It is rich between 2500rpm and 3500rpm, most running is 3500-5500 rpm unless on dry ground or pushing through thick stuff and then it maybe WOT for 15-30 min sometimes, but when frog gigging will stay 1500-3000rpm for hours.
My first question is at what rpm does it go from using idle and transition slot to mostly using prim jets.
Second question is how to fix rich between 2500-3500rpm.
Attached is a carb sheet with RPMS AFRs and Vacuum readings any help would be greatly appreciated

[Right hand drive]

Suggestions:

1) Ensure ignition and it’s curve is well sorted

2) That’s a very rich calibrated 650 (as results show). As a new baseline look at:

.028” mab
Remove & plug bottom e-bleeds
Drop to .031” IFR. Eenlarge or reduce .001” if too rich or lean in rpm area of concern. Fine tune with +/- iab.
Drop MJ 3 sizes each end
Up pvcr for WOT if needed but don’t be surprised if more jet comes out.

[Right hand drive]

You can delve even deeper and tap for low IFR and install and play with transfer slot restrictions. It’s how precise you want the overall AFR curve.

[1109RWHP]

What does eliminating the lower e bleeds do?

[Right hand drive]

[RFSPHPbb]

>>>My first question is at what rpm does it go from using idle and transition slot to mostly using prim jets.

really easy to see on a boat. pull the air filter or whatever it has on top the carb. with a good flashlight look down the primary venturiis while gradually increasing the throttle/RPM. Best to have an assistant. Try not to open the throttle too much, getting into the power valve. look for the boosters to start emitting a white fog in the center. Depending on the overall combination in place this might be 2000-3500 RPM. if it's a big engine with a small carb, it'll be sooner. larger carb on smaller engine will start the mains later. below the RPM where the boosters swamp out the idle transition circuits changing the main jets will have little or no effect on cruise AFR.

Clear as mud? Good.

you can do this on the water too, but the assistant becomes more critical due to traffic.

[twb119]

Right hand drive, tying to understand what you want to do to the carb with your changes, going to smaller MAB .032 down to .028 and plugging bottom emulsion bleed will decrease the air in the emulsion, lowering the MJ -3 will then balance the emulsion causing the fuel curve to flatten out, leaning the 2500rpm 4000rpm and not as much 4000rpm to when the power valve opens around 5300-5400rpm.
Will double check ignition/timing curve, when installed new carb i checked it and used a IR on headers to check temps and they are very close i don't remember the temps just that they are close. The spark plugs 3,4,5,6 looked a tad leaner than 1,2,7,8 over all they looked good after a 1-2 minute wot pull, i didn't check them after a 3500rpm max pull, but probably rich looking just going by AFR.

RFSPHPbb looking at AFR curve and thinking about it looks like MJ are coming in to play a little after 2000rpm, but will double check.
One nice thing about this being on airboat is the prop is like a dyno to a certain extent,and all you need to do is strap the boat to something solid while on land and tinker with it.

What I am shooting for is AFR 13.5-14.3 between 2000-5300rpm and AFR 12.5-13.5 when power valve opens around 5300-5400rpm to WOT, after i get the carb tuned will increase the prop pitch so WOT is 5600-5800rpm to get the cruse rpm down lower.

My plan was tinkering with it this weekend but work has reared its ugly head and will be leaving for a two month job out of state a week early, i leave tomorrow just got the call this morning, so i will have to get back to y'all on the changes and how they turned out when i get back in September.

Thanks for everyone replying.

[Right hand drive]

Yep, pretty much what I was getting at.

Reducing mab will have a delay and leaning effect when the mains begin compared to larger mab and then when mains are operating in earnest have an enriching effect adding less air to the mix. Conversely larger mains encourage earlier and richer start of the mains due to the available air to the top emulsion that lifts fuel to the booster. As cfm through the carb increase too much mab can add too much air and trend lean, even worse combined with too much emulsion. Because of the lean trend MJ is usually sized to cover the lean top end exacerbating the earlier and richer start. It’s a see-saw proposition. .025” mab you’ll be holding back start of mains but really help enrichment of WOT (think what that would do to MJ requirements). With .039” mab the mains supplying fuel in the midrange won’t be a problem but will displace fuel in the main well leaning out.

This all has to work with IFR and IAB combination for transition to the mains that does not overlap too much or not at all. Then there is size and amount of emulsion that influences the curve.

With changes suggested do one only at a time. Plug bottom emulsion first. You have the ability to collect data so start with changing the IFR and see what that does to AFR and how far into revs the change is observed, you might find something you like. When thats done don’t change MJ yet and experiment with mab size and it’s effect through the full range. If say a .026” mab has a leaning effect on that 2500-3500rpm range from where it was and becoming richer in the 5500rpm area then drop MJ to regain 5500rpm area AFR and see effect on 2.5-3.5k area. Gone too lean in the lower regions go up to .028” mab and run through the experiment again. I think you will see what I am getting at. When you get close to what you are looking for AFR wise then the IFR may need revisiting but before doing that do a few jumps either way with iab to gauge effect, .065”s and .075”s if starting point is .070”. Going through all that you will be getting a feel of what changes what and how much for more educated guesses of next move. All this might get you to an outcome you are happy with but most guys with an AFR gauge that like tuning will seek finer tuning. This is where emulsion can get you there. Put the bottom e-bleeds back in and observe effect of AFR and how it’s response feels, change top e-bleed size and do same. Always note how the AFR change affects how it feels to drive.

I think I have filled your head with enough now and I look forward to your results when reporting back. Seek advice and information from as many varied sources as you can and align that with what your findings are when experimenting.

Good luck.

[Right hand drive]

Forgot to mention if your tuning with an AFR gauge, using AFR scale and the fuel used is not 14.7 stoichiometric then it will be telling lies. Default the gauges use lambda and multiply by 14.7 for AFR scale. Check your fuels stoichiometric and if 14.7 all good but if getting too far from 14.7 adjust to using lambda scale.