Andy B.
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What are the pros and cons its an 99 502 mpi? I mainly boat at mead with an occasional trip to Havasu.
Stock heads going to machine shop for some work nothing crazy and not sure on intake the motor has emi thunder exhaust also.Depends on what you want to accomplish really , what heads ? what intake is planned ?
Depends on what you want to accomplish really , what heads ? what intake is planned ? we run 85 0 dfdp Holley/clones on all the 496 strokers , but with upgraded heads, cam , fuel pump etc View attachment 943758
Stock heads going to machine shop for some work nothing crazy and not sure on intake the motor has emi thunder exhaust also.
I don't have a lot of knowledge with carburetors do they need tunning every year? Boat sits in my garage from middle of November until late February.
What are the pros and cons its an 99 502 mpi? I mainly boat at mead with an occasional trip to Havasu.
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Are there no tuning options available for the 502 MPI? Just curious.
Relatively low maintance , actually less to go wrong , tune should stay the same (once done) from on use to the nextStock heads going to machine shop for some work nothing crazy and not sure on intake the motor has emi thunder exhaust also.
I don't have a lot of knowledge with carburetors do they need tunning every year? Boat sits in my garage from middle of November until late February.
exactly but the ones who complain about them the most are usually starting out with problem carbs anywaysNo problems with a PROPERLY tuned carb set-up. I would run one without hesitation
If you want to take on the frustrating and satisfying feeling of a properly tuned carb then go for it. I'm in Vegas and can offer some assistance. I'm no expert mechanic but have researched until pinkies go numb (I'm sure some of you know that reference) and have successfully got mine right twice with different blowers.
View attachment 943829 View attachment 943830
If your going to a 540.
The older EFI found on the 502 and 454 is not failsafe. I've had plenty of friends experience problems from injector issues, to TPS issues and everything in-between. However, when working correctly it's turn-key and safer.
Carbs are simple to work on and shouldn't require any tuning after initial set-up. They are prone to internal and external leaks if they sit a long time, which can be catastrophic if the blower isn't utilized correctly. It would be pretty simple to get over 500hp out of a 502 with a carb, not sure about tuning the older injection.
If you do go carburetor I have a bunch of great parts listed in parts section. Everything you need as I am going opposite way to fuel injected. Aeromotive pump and regulator, Eddlebrock Air gap and holley 4 barrel carb, billet MSD distributor. All in great condition and ready to bolt onto a standard deck block.No blower nothing crazy just want reliable power.. Barry is taking good care of me.
I've seen your boat out by Gator this summer I'm pretty sure it the scarab in your avatar right? Nice boat!
You can actually get the quads to work pretty decent with some minor drilling mods. Still prefer a Holley though.Sounds like a quadrajet is the perfect fit for you.
Andy, just get an electric waverunner
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Carb if you're old school and can turn your own wrenches to fix shit. If you're not mechanically inclined regardless of what system(ie. have to get it worked on by others) then do efi and make the boat more user friendly.
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If all that fails then go plug your E-waverunner while in standing in 3' of water
going from EFI back to a carb is akin to "getting back with an X you already dumped because its easier".
i understand the argument for simplicity.....I really do....and a carb will get you that.
however, EFI will net you better fuel economy, better engine longevity, an overall "happier" running engine and an engine that has many more safeguards and features you simply don't have with a carb.
that being said......IT IS more complicated to setup. The biggest issue i see is people will spend huge sums of $$$ in billet parts....but when it comes to the electronics......they skimp and go with the cheapest junk or factory hacks they can find.
the EFI companies (like Holley) tout "self tuning" and all sorts of other BS trying to dumb down the electronics and installation and only given EFI a bad name.
it is possible to get a good marine EFI system setup. but if you want CHEAP...then stick with a carb.
So what about the original merc efi it did get me to 800 hrs.
this is the equivalent to an electronically controlled carb. another low budget poor excuse compared to modern EFI.So here is a question...... has anyone ran a Holley Sniper EFI system on a boat. I know they are self learning, and have great reviews with mild cars engines. I don’t know how aggressive a cam it can accommodate, and how radical a motor will it support.
this is the equivalent to an electronically controlled carb. another low budget poor excuse compared to modern EFI.
i haven't and while i am sure in the world of the internet there is someone out there doing it......all you have to do is take a look around and you will see it isn't being done for a reason.ok. I get the carb comparison. But ya didn’t answer the question, has anyone ran it on a higher HP boat engine
Funny, sounds like the same thing people like to do with carbs, they never get them set up properly and just blame it on the carb.here is the problems with your old MEFI system.
1. the software to break into this system is a FUCKING NIGHTMARE to work with. it isn't a real-time tuning platform. its also VERY limited in its capabilities.
2. your old wire harness is probably shot. Most people fail to recognize the ECU takes its input information it gets from sensors/wiring and any issue with the sensors and wiring are usually misunderstood as a "tuning issue" instead of recognizing the intermittent nature of wiring issues.
3. the merc MEFI system is CRUDE. you do realize its TWO CHANNEL fuel? it has no logging capability, no internal wideband 02 capability, limited additional sensor inputs and on and on.
4. the cost of high quality aftermarket systems have come WAY down. but that's just the beginning. most don't recognize what it really takes to properly setup up all aspects of an EFI system, and then blame it on tuning or whatever instead of recognizing its design issues from the start. example......people just install a high pressure fuel pump when they convert to EFI, run some new lines and call it good. the problem is boat fuel tanks don't have any baffles and starvation of the pump when low on fuel or in rough water causes fuel pressure (that don't always show up on a gauge) issues that commonly get blamed on the computer. addressing fuel pressure stability in a boat has nothing to do with the computer but always misdiagnosed as a tuning issue.
ok. I get the carb comparison. But ya didn’t answer the question, has anyone ran it on a higher HP boat engine
if this were the case.....merc and the other manufacturers would still be running carbs.Funny, sounds like the same thing peoe like to do with carbs, they never get them set up properly and just blame it on the carb.
I have 1 experience with the sniper efi on a boat. A competitor destroyed a brand new engine in a boat with one (a moderately built big block). He ended up owning the boat, i dont know if the setup was wrong or just a garbage product but I looked at it and didn't like what I saw. I told him to fix it right, we need to take it back to its original configuration with a carburetor. People put too much stock in efi, ot is not the end all be all.
Fwiw I see a lot more high hour carbed engines than I do efi engines. Efi kills marine engine when it goes wrong
Wasn’t that known as poor man’s fuel injection back in the day?Sounds like a quadrajet is the perfect fit for you.
if this were the case.....merc and the other manufacturers would still be running carbs.
efi is complicated and the problems i see are due to poor setup and implementation being done by people that shouldn't be doing it because they fall for the snake oil sales pitch of how simple itis.