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Discussion Starter #1
Anyone converted one of these to a carb and distributor? Got a dart intake and looking for the rest of the parts. Ignition, cooling and such. Any advice appreciated!
 

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496

I think the trouble you will run into is the intake ports are way different and many other things will come up also, there will be other guys come along that will let you know, thats what came to mind first for me though. Probably could be done but it would take some modifying
 

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Discussion Starter #3
My dart intake is actually made for the 8.1. Trying to figure out the cooling set up mostly and what size carb to run.
 

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You're actually wanting to go BACKWARDS? Are you also going to take the EFI off of the PU, SUV, or sedan you drive daily?
 

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You're actually wanting to go BACKWARDS? Are you also going to take the EFI off of the PU, SUV, or sedan you drive daily?
Here we go again. I dont think hes wanting to put the 496 in the wifes SUV.
I own both and have much more BS from the 502 mpi in my daytona than I will ever have from my C&S carb on the jet.
To each their own man but when I get tired of playing with the jet I'm going to build a twin turbocharged, intercooled engine with a blowthrough carb for the 25' daytona and sh-t can that pos efi . Then the only problem will be trying to come up with a drive that will live.
 

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Name ONE BENEFIT to going backwards from EFI to CARB on a Vortec 8100. Just ONE.
 

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A average old wrench can still work on it. You need to be young and smart to work on F.I. :D

Right Bob?
I have yet to see anyone on the lake WORKING on theirs.
 

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496mag/HO Pros vs. Cons of converting backward from EFI to carb.

PROs:
1. "Anyone" can wrench on a carb.

CONs:
1. No more ECM to tell what sensor has gone bad.
2. No more ECM to save the motor if there is low oil, low oil pressure, low fuel pressure, high water temp, low water pressure.
3. No more knock sensor to keep the motor from detonation.
4. Now have to pump throttle for cold starts.
5. Now have rich warm starts.
6. No more compensation for altitude / density altitude.
7. Lack of precise fuel distribution.
8. Possibility of fuel puddling in the intake.
9. Have to run the blower EVERY time you start.
10. Lack of RPM compensation when in-gear / out-of-gear.
11. Power valve(s) to blow out / leak.
12. Possibility of vapor-lock.
13. Fuel available when key is off (run-on / dieseling / hydro-lock)

I'm sure I left some out.
 

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Discussion Starter #11
Ok. Heres the deal. I got this long block from a local boat shop not being really familliar with the 8.1. So now i have this motor and not sure what is possible to do with it. I cant afford to buy a stand alone efi or come up with all the stocker crap and stuff. I have a carb intake for this motor and thats it. Throttle bodies? I dont know. Keep the suggestions coming! Any help is appreciated. Should I sell this and get a 454 or 502? My ears are open. Thanks guys.
 

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496mag/HO Pros vs. Cons of converting backward from EFI to carb.

PROs:
1. "Anyone" can wrench on a carb.

CONs:
1. No more ECM to tell what sensor has gone bad. No sensors to go bad
2. No more ECM to save the motor if there is low oil, low oil pressure, low fuel pressure, high water temp, low water pressure. Never had any of those problems
3. No more knock sensor to keep the motor from detonation. Never had my stuff that far out of tune, guess i must be good , huh?
4. Now have to pump throttle for cold starts.Lazy
5. Now have rich warm starts. Not with the C&S
6. No more compensation for altitude / density altitude. I dont fly my boat that high
7. Lack of precise fuel distribution. Wrong
8. Possibility of fuel puddling in the intake. Never had a problem with that, must be lucky.
9. Have to run the blower EVERY time you start. should be doing that anyway
10. Lack of RPM compensation when in-gear / out-of-gear.
11. Power valve(s) to blow out / leak. No worse than all the sensor to go bad
12. Possibility of vapor-lock. That can happen with some efi systems too
13. Fuel available when key is off (run-on / dieseling / hydro-lock) Must just be me but you seem to have alot of trouble with something so simple.
I'm sure I left some out.
Yet as great as you think efi is, they still give fits that even some of the guru's cant figure out. On my 502 MPI for instance. If you rev it up in neutral it will stay @ 1100 rpms and if you kill it and refire it idles back down just fine. Have put a new IAC or what ever you call the pos and checked everything they PROS could come up with but still does it.
Another issue, If you run hard for a mile or so then come down off plane and let it idle the temp guage starts dropping and when it gets below 140* the engine thinks its cold and start blubbering from being to rich, if you idle it up a little the temp will stay up and all is fine. Put new sea water pump, thermostat, pulled all the hoses and everything is clean. Doesnt ever run to hot. Seems as though with the 29pitch dual props on the Blackhawk drive that it pulls the motor down low enough at idle that the circulator pump isnt flowing as much water as the seawater pump and the seawater pump is just flowing cold water past the temp sensor and out the exhaust.
I've learned to deal with these issues and dont have any trouble using the boat, but with that being said I wouldnt have to be dealing with that BS with a carbed engine. The boat I had before this one was a carbed BBC in a 23ft Regal, it was an older boat . Had it for yrs and never touched the carb or hell the whole engine except to change the oil. And it NEVER had any of the issues you claim. And it didnt give the BS this new EFI deal does either.
Dont go telling me just how easy it would be to fix the little problems either. I've talked to some of the best in the business on here and tried it all. Still does it. Doesnt cause any problems as long as you dont free rev it , which I seldom ever do, and when coming off plane just keep it above idle for a few seconds , but still no carb.

Sorry to jack your thread OP , but I would stay carbed, JMO.
 

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OK, so the original poster now says he only has a long-block. While carb STILL is going backwards, at least he is not contemplating pulling off a MPFI intake and all of it's efficient hardware. He just looking to COMPLETE a motor. And in that respect, I would suggest you just look at a complete Gen IV, V, or VI motor instead of mess with a Gen VII. Not being familiar with it, you will be hunting for the pieces and parts to make it what you want - and that won't be easy.

Hass, you are going to the wrong people on that hanging-at-1100-deal. If you had a laptop connected, you could watch either the TPS being hung-up just long enough for you to shut it off, or you would be able to see the marker hanging around either a map reading or IAC follower reading that it shouldn't. Someone is missing something, and it's not THAT hard. I tune EFIs all the time and you can watch ANYTHING YOU WANT - you just have to know which screen to watch. Rinda makes laptop software to view all of the tables. There are others too that make software to adjust and follow the MEFI ECMs.

The 140-degree thing is probably as simple as MOVING the CTS to somewhere more stable? REAR water runner of the intake where flow is not as prominent AND cold water is not present? That being said - a carb is blind to temp and CAN'T ADJUST for cold/hot motor/water temps. So, you WILL have an un-correctable in-efficiency at some point in the temp spectrum. Be it rough cold-start or rich hot starts/idling. Jetting is FIXED on carbs, whereas it's constantly variable on EFI. Yes, the motor will PULL what it wants throught the venturies, but what's on the other side is STILL LIMITED and fixed. The EFI will adjust for altitude, heat, loaded boat / empty boat. EFI adjusts HUNDREDS of times per minute / if not per SECOND (some systems), a carb just sits there with a dunce cap on.

I rode on a friend's Magic deck a month ago. 604" BBC, carbureted. It runs nice. Calm cam, 750hp, nothing outrageous. But without a choke, he fires it cold and it idles at about 500, just chugging. Not smooth at all. HAS to let it warm up a bit before going for fwd/rev on the outdrive. THEN, even when warmed up, that 30" prop drops it 300-400 rpm. So it dips and then recovers - with a bit of a brown "puff" from the tips. A bitchen carb just can't do the multitude of adjustments necessary to make in/out of gear transitions NEAR as smooth as even a HALF-ASS EFI tune can. Plus, he complains of a bit of fuel puddling on real cold mornings - where MPFI has the fuel being shot right at the intake valve. DO THAT with a carb.

What SUPER car or SUPER boat COMES WITH A CARB THESE DAYS??? You can't tell me Alexi is really worried about EMISSIONS on his 800ci, 2000hp super motor! I don't see any carbs NEAR that thing. If carbs were ALL THAT, they would have a place there as well.

You're a smart guy, Hass. You can't tell me otherwise. So, I know YOU know that all of the drivability and efficiency you get in your daily driver is JUST AS GOOD for a boat. Do we still play RECORDS and TAPES? Still ride on BIAS tires?? Do we not POWDER COAT more stuff than paint?? I have every bit of belief that you have your blow-through dialed in just as you want it. To be perfectly honest, you probably COULDN'T improve on your particular setup with EFI - aside from a few touches to under-the-curve (cold / high altitude) areas of the fuel curve. BUT, we're not talking specifically about blow-through turbo setups here. We're talking modest HP, ANYONE behind the wheel, turn-key drivability.

So, touching on emissions - we all know that is why all mfgs have gone to EFI for their package engines. So that poises the question to you - - why CAN'T they make just as much HP/TQ and maintain their emissions with carbs??? If carbs are the end-all-be-all of fuel-mixers.......why are they so obsolete in the air - on land - and sea???

Again on the CTS issue - I wholeheartedly believe ALL boats should have closed-cooling! Heat-exchangers are so prominent now, I don't see why someone would want to run WITHOUT one. Mine sits at 150-160 (160 therm) no matter what. WOT, idling, cruise. So, the motor doesn't get shocked with cold water. Every time you fire your 502 up, it gets a shot of cold water through it from the lake. No bueno.
 

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I imagine you got a SMOK'N deal on this thing because anything the marine sealer got over scrap was a blessing.

to my knowledge, you can use a stock standard deck dizzy with the Dart manifold.

As much of a loser this motor is, the single best thing that you could do to the long block you have is drop a carb on it. If cammed correctly, it has the potential to bury a Merc 496 HO without mercy.
It will, and never can be what a MKIV thru Gen 6 is. But your on the right track to making it better than you could ever hope for with the stock Merc/GM EFI without breaking the bank.

I have to laugh at the guys that buy into Raylar's BS, and dump tons of cash into these things when Dart has now come to their rescue for a lot le$$ and alot more potential.

Some good qualified head work and the right camshaft, thing can crush a Merc/GM EFI 8.1 and for alot less ca$h.



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OK, so the original poster now says he only has a long-block. While carb STILL is going backwards, at least he is not contemplating pulling off a MPFI intake and all of it's efficient hardware. He just looking to COMPLETE a motor. And in that respect, I would suggest you just look at a complete Gen IV, V, or VI motor instead of mess with a Gen VII. Not being familiar with it, you will be hunting for the pieces and parts to make it what you want - and that won't be easy.

Hass, you are going to the wrong people on that hanging-at-1100-deal. If you had a laptop connected, you could watch either the TPS being hung-up just long enough for you to shut it off, or you would be able to see the marker hanging around either a map reading or IAC follower reading that it shouldn't. Someone is missing something, and it's not THAT hard. I tune EFIs all the time and you can watch ANYTHING YOU WANT - you just have to know which screen to watch. Rinda makes laptop software to view all of the tables. There are others too that make software to adjust and follow the MEFI ECMs. Cool, so now all I need is a new laptop, software, cables and some geek on the phone to tell me how to use it.
The 140-degree thing is probably as simple as MOVING the CTS to somewhere more stable? REAR water runner of the intake where flow is not as prominent AND cold water is not present? That being said - a carb is blind to temp and CAN'T ADJUST for cold/hot motor/water temps. So, you WILL have an un-correctable in-efficiency at some point in the temp spectrum. Be it rough cold-start or rich hot starts/idling. Jetting is FIXED on carbs, whereas it's constantly variable on EFI. Yes, the motor will PULL what it wants throught the venturies, but what's on the other side is STILL LIMITED and fixed. The EFI will adjust for altitude, heat, loaded boat / empty boat. EFI adjusts HUNDREDS of times per minute / if not per SECOND (some systems), a carb just sits there with a dunce cap on.
I thought about moving the CTS but was told that Merc has an untold amount of $$ in designing this sytem that I'm getting ready to modify. And to leave it factory. Moving that CTS 6" from the path of the incoming water coming from the seawater pump that is heading directly to the thermostat outlet and putting it in the intake, under the thermostat would stop the cold problem but might go the other way and make it read to hot at times and set off the buzzer. What BS. Love my carbs.I rode on a friend's Magic deck a month ago. 604" BBC, carbureted. It runs nice. Calm cam, 750hp, nothing outrageous. But without a choke, he fires it cold and it idles at about 500, just chugging. Not smooth at all. HAS to let it warm up a bit before going for fwd/rev on the outdrive. THEN, even when warmed up, that 30" prop drops it 300-400 rpm. So it dips and then recovers - with a bit of a brown "puff" from the tips. A bitchen carb just can't do the multitude of adjustments necessary to make in/out of gear transitions NEAR as smooth as even a HALF-ASS EFI tune can. Plus, he complains of a bit of fuel puddling on real cold mornings - where MPFI has the fuel being shot right at the intake valve. DO THAT with a carb.

What SUPER car or SUPER boat COMES WITH A CARB THESE DAYS??? You can't tell me Alexi is really worried about EMISSIONS on his 800ci, 2000hp super motor! I don't see any carbs NEAR that thing. If carbs were ALL THAT, they would have a place there as well.
You couldnt get it past Big Brother. That 800" deal is a beatiful engine and powerful, but many are making that much power with half the CID today with turbos.
You're a smart guy, Hass. You can't tell me otherwise. So, I know YOU know that all of the drivability and efficiency you get in your daily driver is JUST AS GOOD for a boat. Do we still play RECORDS and TAPES? Still ride on BIAS tires?? Do we not POWDER COAT more stuff than paint?? I have every bit of belief that you have your blow-through dialed in just as you want it. To be perfectly honest, you probably COULDN'T improve on your particular setup with EFI - aside from a few touches to under-the-curve (cold / high altitude) areas of the fuel curve. BUT, we're not talking specifically about blow-through turbo setups here. We're talking modest HP, ANYONE behind the wheel, turn-key drivability.

So, touching on emissions - we all know that is why all mfgs have gone to EFI for their package engines. So that poises the question to you - - why CAN'T they make just as much HP/TQ and maintain their emissions with carbs??? If carbs are the end-all-be-all of fuel-mixers.......why are they so obsolete in the air - on land - and sea???

Again on the CTS issue - I wholeheartedly believe ALL boats should have closed-cooling! Heat-exchangers are so prominent now, I don't see why someone would want to run WITHOUT one. Mine sits at 150-160 (160 therm) no matter what. WOT, idling, cruise. So, the motor doesn't get shocked with cold water. Every time you fire your 502 up, it gets a shot of cold water through it from the lake. No bueno.
I can see where you would desire this , since you love efi. I personally dont have any problems with the lake cooling, been using it for yrs on many many boats without issues(except the efi BS)
Beer I'm also aware that you are an intelligent fellow , so dont tell me that you believe that your friend with the 600" deal has to live with those problems he's experiencing. You know just as well as I do that with a tiny bit of tinkering that those problems would be gone forever. If you just buy a stock carb, pull it from the box, plop it on there and expect it to operate perfectly in every way, then yes, you will be disappointed.
The Regal I had came with a 454 with a damned old quadrajet . And I'm telling you as you backed it down the ramp you pump the throttle once and hit the key and it would fire and idle @ 600rpms, never missed a beat, never flooded, never had hot start issues. As a matter of fact, the guy that bought it went for a ride in it, bought it , took it home and used it a couple times then called me and wanted to know if it was carbed or efi? I told him to leave the hatch down & use it as it would be trouble free, it was carbed. Hes had it 3 yrs now and hasnt touched it. That carb is now 25yrs old and has never been off the intake and still runs as good as new. Maybe we're just lucky.
The move to efi by the rest of the world is Big Brother and the emmisions police.
 

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I imagine you got a SMOK'N deal on this thing because anything the marine sealer got over scrap was a blessing.

to my knowledge, you can use a stock standard deck dizzy with the Dart manifold.

As much of a loser this motor is, the single best thing that you could do to the long block you have is drop a carb on it. If cammed correctly, it has the potential to bury a Merc 496 HO without mercy.
It will, and never can be what a MKIV thru Gen 6 is. But your on the right track to making it better than you could ever hope for with the stock Merc/GM EFI without breaking the bank.

I have to laugh at the guys that buy into Raylar's BS, and dump tons of cash into these things when Dart has now come to their rescue for a lot le$$ and alot more potential.

Some good qualified head work and the right camshaft, thing can crush a Merc/GM EFI 8.1 and for alot less ca$h.
How much experience do you have with this engine? How much experience do you have with the Raylar cylinder heads for this engine? Just curious.
 

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Discussion Starter #17 (Edited)
Thanks for the responses! Lots of good info from both parties. The engine in question only had a couple hours on it. The shop cammed it and could not get the efi to tune correctly. Don't have alot of info. The customer was impatient and had them replace it. So now it sits in my shop. I think I'm going to go ahead with the build up and see what happens. Suggestions on a carb and cooling system would be appreciated. Also what dizzy and controler? MSD? Thanks! This is my first endeavor with an 8.1. Seen the raylar stuff is all.
 

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How much experience do you have with this engine? How much experience do you have with the Raylar cylinder heads for this engine? Just curious.
Enough to know the engine is a dead end performance wise, or ther block and heads would highly sought after pieces. Performance guys aren't morons. If there was ANYTHING desirable there, they would be getting snatched up right and left. They are infact being ignored. TOTALLY.

As for the Raylar stuff, again, a huge seller in the performance world:)sphss Gigantic HP gains for the cash outlay:)sphss You take your Raylar equiped 496, and I will spend the same cash on a MKIV stroker 496 and we'll meet up and you show me what you got. Bring lots of cash!!!!!!!!
I don't have need to have ANY experience with a 500 inch Caddy to know they are next to worthless. I don't need to eat a shit sandwich to know I don't want one.



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Enough to know the engine is a dead end performance wise, or ther block and heads would highly sought after pieces. Performance guys aren't morons. If there was ANYTHING desirable there, they would be getting snatched up right and left. They are infact being ignored. TOTALLY.

As for the Raylar stuff, again, a huge seller in the performance world:)sphss Gigantic HP gains for the cash outlay:)sphss You take your Raylar equiped 496, and I will spend the same cash on a MKIV stroker 496 and we'll meet up and you show me what you got. Bring lots of cash!!!!!!!!
I don't have need to have ANY experience with a 500 inch Caddy to know they are next to worthless. I don't need to eat a shit sandwich to know I don't want one.
I agree - a 496 with a carb should totally be obsolete and not used at all. Same for a 500 inch carb'd Caddy. I have a restored 75 ElDorado with the 500 in it. Planning on TBI for it to get rid of the obsolete carb. So, I agree that the carbureted motors should be obsolete.
 
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