Air fuel ratio for direct drive

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One Eyed Gator
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Re: Air fuel ratio for direct drive

Postby One Eyed Gator » Thu Apr 18, 2019 7:15 am

Can't you tune it for WOT and use a piece of Wire in the IFR ( old school trick) to lean it out at idle but will be a little fat at cruise.

Depending on the metering plate you can also drill and tap IFR and emulsion circuit for 6/32 brass blanks and drill them to the size you need.

Just some thoughts

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keys2pines
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Re: Air fuel ratio for direct drive

Postby keys2pines » Thu Apr 18, 2019 7:30 am

One Eyed Gator wrote:Can't you tune it for WOT and use a piece of Wire in the IFR ( old school trick) to lean it out at idle but will be a little fat at cruise.

Depending on the metering plate you can also drill and tap IFR and emulsion circuit for 6/32 brass blanks and drill them to the size you need.

Just some thoughts

I was just looking around online about drilling the metering plate and I came across Holley secondary metering block conversion kit 34-6, which says it's for 4160 style carbs with side-hung floats, which is what this carb is. I just emailed the guy at Holley again, asking why this can't be used. He told me there was no conversion kit, or a different metering plate available. I was looking into EFI and it's going to cost an honest $1100 after you add the new fuel pump, lines, etc.
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John Fenner
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Re: Air fuel ratio for direct drive

Postby John Fenner » Thu Apr 18, 2019 9:03 am

I have put those kits on many of those carbs.
I never finish anyth,,,.

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keys2pines
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Re: Air fuel ratio for direct drive

Postby keys2pines » Thu Apr 18, 2019 9:24 pm

John Fenner wrote:I have put those kits on many of those carbs.

Yea, I don't think this guy knows what he's talking about. I ended up finding a quick fuel metering plate that has provisions for jets and comes with a modified float to clear the jets. It was on the Holley website. I emailed the tech back and he said "The 34-6 that you asked about will not work because it is a metering block conversion kit not a metering plate. However the quickfuel 34-2QFT will work on the carb, My mistake." I still think he's wrong because the point of a conversion kit is to get rid of the plate, but anyways I ordered the plate and I'll get more tuning done next week. Thanks again for all the help!
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Rich Andrews
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Re: Air fuel ratio for direct drive

Postby Rich Andrews » Thu Apr 18, 2019 10:33 pm

Or... get with Ed MAck or another carb expert do it right and preserve the motor!
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Re: Air fuel ratio for direct drive

Postby Krahammer » Fri Apr 19, 2019 9:36 am

You can't go wrong with Mr.Mack. He is the best carb guy there is.

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keys2pines
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Re: Air fuel ratio for direct drive

Postby keys2pines » Fri Apr 19, 2019 8:46 pm

Rich Andrews wrote:Or... get with Ed MAck or another carb expert do it right and preserve the motor!

I hear you, but I put my own engine together at 18 years old. I'm not a newbie by any means, I've just never messed with carbs or the rpms a direct drive airboat runs. I have a wideband and a dyno (prop rpm), I'll get it right, if not, it's going EFI :D
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Rich Andrews
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Re: Air fuel ratio for direct drive

Postby Rich Andrews » Tue Apr 23, 2019 9:00 pm

Yup, and my buddy has been racing cars since he was 18 and thought he knew it all.... go ahead w that efi let us know how that works out
I'll have my Manatee burger medium please...just say NObama

14x8 deckover FELBER 397ci.. HP ???..just stay back!!

LOHA is AHOL backwards

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keys2pines
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Re: Air fuel ratio for direct drive

Postby keys2pines » Wed Apr 24, 2019 7:40 am

Rich Andrews wrote:Yup, and my buddy has been racing cars since he was 18 and thought he knew it all.... go ahead w that efi let us know how that works out

No offense, but if I thought I "knew it all" I wouldn't be here asking questions. As for the EFI, there is a reason new cars don't come with carbs. I'm positive it would make more power and be more efficient with EFI and a coil-per cylinder system than the carb and distributor. Even the aircrafts are rated for more HP with fuel injection. :salute:
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Re: Air fuel ratio for direct drive

Postby SWAMPHUNTER45 » Wed Apr 24, 2019 8:42 am

I would agree that EFI is going to be more efficient, the reason that I personally have not crossed over is two fold. First the system is only as good as the system, if that makes sense. It's sensor or sensors ability to read gasses and then transmit data to the ECU to read and adjust is the key. With this being a somewhat new product line to the after market and so many different variations, personally I am waiting for them to work through the process. The other concern is with the technology comes glitches or defects and a EFI failure in the field can not be quickly overcome. If my fuel pump or HEI fails we have a micro pump or module to limp us home. If that ECU or high pressure pump would fail then I don't think I could get home without assistance. Cost is prohibitive on carrying a spare ECU at this point and the systems are auto not marine. When you seal them and encase then heat becomes a concern. At least at this point in the development these are concerns.

I have heard that one of the higher dollar systems is now using 2 pumps and if the primary fails the smaller pump can limp you back. This is an example of the type of advancements that time and market demand will help with the products evolution. With Aircraft almost everything is redundant and that is a hard to beat concept. Until then I am going to run a slightly rich mixture and stay on a carburetor. I would recommend that until you cross over you work to accomplish the same and rely more on reading your plugs and tailpipes. A dark ashen slate grey in the pipes and golden brown on the plugs is a happy and safe engine.

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Re: Air fuel ratio for direct drive

Postby hdsadey » Wed Apr 24, 2019 10:07 am

Swamp they do make a "marine grade" system from FAST EFI. More geared towards a Mercruiser setup.
Screenshot_2019-04-24-09-58-13.png

I been running a Fitech for 2 years with little problem. I now carry a spare pump since finding aluminum shavings in the fuel filter causing the engine to starve for fuel. Thought I had a dying pump. So now I have a spare. Airboats are more auto than marine IMO. They are sealed against the elements in an engine compartment. They surely don't get the heat of being under a hood in an airboat. I don't think I will ever go back. :D
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SWAMPHUNTER45
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Re: Air fuel ratio for direct drive

Postby SWAMPHUNTER45 » Wed Apr 24, 2019 11:15 am

I have read about guys who put ECU and ECM in sealed boxes and the self generated heat bakes them. That was my concern. Some will adapt a PC fan but often times it will fail in the marine environment as it was made to be in a controlled climate.
Glad your finding success with it. I'm still old school for now but Mr Branch has put an EFI 520 inch Caddy out on the street. He likes them but I'm not convinced they are built well enough for my application at this time.

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Re: Air fuel ratio for direct drive

Postby hdsadey » Wed Apr 24, 2019 12:58 pm

The ecu is built into the throttle body on the Fitech. The hand held controller is clamped in like a cell phone holder. Don't have to have it plugged in for it to operate.

I've had alot of experience with them. In the hotrod world everyone has seen to forgotten how to treat carbs in this day of fuel injected everything driving. Garbage ethanol fuel is not kind to toys that sit for extended periods. It was easier to sell them the stand alone systems so they could enjoy themselves instead of calling me complaining their hotrod won't run right lol. :lol:
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keys2pines
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Re: Air fuel ratio for direct drive

Postby keys2pines » Wed Apr 24, 2019 3:57 pm

Welp, I changed the jets that were in there (62 mains and secondary metering plate 64) all the way up to 70 mains and 74 secondary, 74 was the highest I had. No change in AFR, or max prop speed. The power valve went bad while I was testing and my AFR went straight to 10.0. I verified the power valve went bad by turning the idle mixture screws all the way in and the engine was still running. I went and got a new power valve, and I'm back to 13.6. Seems like there is a fuel restriction somewhere in the carb, right?
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One Eyed Gator
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Re: Air fuel ratio for direct drive

Postby One Eyed Gator » Thu Apr 25, 2019 2:04 pm

Have you checked the float drop not float level? If the needle and seat are to far down then the float will never drop far enough to allow the correct amount fuel in. I had it happen when my fuel pressure regulator went bad and spiked the pressure to my carb.

Just a possibility

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keys2pines
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Re: Air fuel ratio for direct drive

Postby keys2pines » Thu Apr 25, 2019 7:41 pm

One Eyed Gator wrote:Have you checked the float drop not float level? If the needle and seat are to far down then the float will never drop far enough to allow the correct amount fuel in. I had it happen when my fuel pressure regulator went bad and spiked the pressure to my carb.

Just a possibility

I didn't check that, but in all honesty I just ordered the efi kit. I'll report back when I have new numbers :old_glory:
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hdsadey
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Re: Air fuel ratio for direct drive

Postby hdsadey » Thu Apr 25, 2019 10:17 pm

Which brand did you order?
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keys2pines
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Re: Air fuel ratio for direct drive

Postby keys2pines » Fri Apr 26, 2019 6:54 am

hdsadey wrote:Which brand did you order?

Same as yours, Fitech. I bought the 180 thermostat and in-tank pump also.
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GeeLeDouche
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Re: Air fuel ratio for direct drive

Postby GeeLeDouche » Fri Apr 26, 2019 7:15 am

I think I'm going to order the Fitech kit for my LS2 soon. Just debating which kit to order. Do you guys run the "Go EFI" kit or the "Ultimate" kit with a new intake manifold?
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keys2pines
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Re: Air fuel ratio for direct drive

Postby keys2pines » Fri Apr 26, 2019 7:20 am

GeeLeDouche wrote:I think I'm going to order the Fitech kit for my LS2 soon. Just debating which kit to order. Do you guys run the "Go EFI" kit or the "Ultimate" kit with a new intake manifold?

I got the go-efi, just the throttle body kit.
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hdsadey
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Re: Air fuel ratio for direct drive

Postby hdsadey » Fri Apr 26, 2019 8:19 am

Awesome. They come with an adapter plate to clamp on the 02 sensor for people that don't have the provisions to weld. I highly recommend a true weld on bung.

Have not done a LS setup yet. The throttle body will work with a carbureted manifold, but I'm not aware of electronic support for the ignition system. If your running a carb already and have a separate system for the coils to fire I believe it will work just fine. You might need a tach signal converter for the unit to properly read RPMS since there a are 8 individual coils.

The Ultimate system has everything incorporated to run the engine without outside support. We've been thinking of purchasing one of these to dyno LS engines without a factory harness and computer.

The nice thing about the LS is the dry manifold. I have this idea of using a World Products Motown LSll block that is SBC bottom end with LS cylinder heads. Best of both worlds, LS breathing but still have a distributor eliminating the electronics also priority main bearing oiling. I think it would make an excellent gearbox engine. Motown blocks can go 4 inch stroke for 427 inches! If anybody's interested let me know we might be able to work with the priving on the first build!
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ryansmoneypit
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Re: Air fuel ratio for direct drive

Postby ryansmoneypit » Mon Apr 29, 2019 9:22 am

new to airboats but not tuning engines. I have one serious question for you guys.

Why are people disregarding the O2 sensor in favor of the plug read method? If I chose to read plugs vs WB o2, my turbo engines might not make it past the first boosted run. Not to mention making the whole tuning process take a lot longer.

Just wondering.

SWAMPHUNTER45
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Re: Air fuel ratio for direct drive

Postby SWAMPHUNTER45 » Mon Apr 29, 2019 12:28 pm

Because I'm old and prefer nitrous, that and it has worked without fail since the advent of the internal combustion gasoline engine.

It can not be out of calibration like a gauge.

Primarily because I'm old!

CarMotorBarge
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Re: Air fuel ratio for direct drive

Postby CarMotorBarge » Mon Apr 29, 2019 9:24 pm

ryansmoneypit wrote:new to airboats but not tuning engines. I have one serious question for you guys.

Why are people disregarding the O2 sensor in favor of the plug read method? If I chose to read plugs vs WB o2, my turbo engines might not make it past the first boosted run. Not to mention making the whole tuning process take a lot longer.

Just wondering.


You should use an O2 sensor and check the plugs. An O2 sensor is a very useful tool assuming it is giving you an accurate reading. You should also double check it by reading the plugs especially for detonation. This is one of the best ways to determine what is happening inside the cylinders.
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Re: Air fuel ratio for direct drive

Postby ryansmoneypit » Tue Apr 30, 2019 8:10 am

Reading through this thread has been interesting. There is a lot of old tech and info about EFI in here. worry about computers overheating, not being waterproof, failing components. Like we all forgot that we daily drive on efi in our cars for the last 30 years..Standalone computers arent much different.

anyway, It has come a long way in just the last couple years. some will never embrace it, others will just enter a new fuel value in a matter of seconds, instead of changing jets around.


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