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GT40 conversion to carb

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macey View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote macey Quote  Post ReplyReply Direct Link To This Post Posted: June-03-2023 at 9:31am
Many thanks for all the input so far. Fresh water use and never left for long periods in the water.
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Gary S View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gary S Quote  Post ReplyReply Direct Link To This Post Posted: June-02-2023 at 7:55pm
Better find out what kind of water he's running in over there as well some of your mods won't live long in some instances 
69 Mustang HM SS
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KENO View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: June-02-2023 at 4:12pm
Well, I suppose you could both use the original gt40 low pressure fuel pump since PCM used that same pump on the carbureted Pro Tec engines, both Ford and Chevy.

It puts out a carburetor friendly 5 to 7 psi

For fire reasons you'll need to have a low oil pressure safety switch like what's in the link  below from one outfit or another since the circuitry that does it on a gt40 will be gone 

Fuel leak, engine off but key still in Run, the pump would just keep on pumping and pumping without the safety switch

It seems to me that only a really strange individual would want to keep his FCC though. Wink

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Jonny Quest View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jonny Quest Quote  Post ReplyReply Direct Link To This Post Posted: June-02-2023 at 3:16pm
Since you asked...

My little Ski Nautique with the GT40 engine is running very well.  No complaints.  As long as the EFI and ECM continue to perform reasonably, then everything remains in the OEM configuration.  HOWEVER, if the EFI and ECM start giving me problems, then I'm just itching for a Winter Project.  If that day ever comes, this is what I would likely do:

- Block is "roller ready" so a roller camshaft is likely
- New roller valve train with roller lifters/rockers, etc.
- Aluminum heads (increase flow, compression ratio and drop weight)
- Aluminum intake manifold (Edelbrock Performer RPM)
- QuickFuel M-650 carb
- Carter electric fuel pump (keep the FCC?)
- DUI distributor with new plugs and wires
- K&N fancy-schmancy air cleaner/flame arrestor
- Audible horn with light for low oil pressure / high temp

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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: June-02-2023 at 9:29am
Well spit those thoughts out Wink
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Jonny Quest View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jonny Quest Quote  Post ReplyReply Direct Link To This Post Posted: June-02-2023 at 9:16am
Damn, KENO!  You know me too well.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: June-02-2023 at 9:03am
You should also be asking for advice on the best distributor, since the gt40 distributor has no mechanical advance and works in conjunction with the ECM to vary timing..

An electric fuel pump should be on the shopping list too.

Jonny Quest, who is pretty much a walking, talking advertisement for Quick Fuel carburetors and DUI distributors (and also dreams of "retroverting" his gt40) will be along to give you his thoughts Wink
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macey View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote macey Quote  Post ReplyReply Direct Link To This Post Posted: June-02-2023 at 7:43am
Hello from sunny Ireland. I have a 2001 196 GT40 EFI. I have been tinkering with this for a while and had various idling issues over my ownership period. My mechanic is a carb lover and is steering me towards removing the fuel injection system and fitting a carb. I understand the carb will not be as efficient as the EFI system and perhaps not as "nice" but my boat is now 22 years old and in great shape so I intend to keep it for some time. Carb stuff is much easier to get over here and mechanics who have the appetite or knowledge to work on my boat are few and far between. Carb set up is significantly more straightforwad. 
I have a few questions:-
Will there be any significant electrical implications with EFI removed (keypad start for example)?
What are the options for getting back to the equivalent horsepower of the EFI system?
Any advice on the best carb and intake to use.
Any other relevant advice would be greatly appreciated.

I understand this is quite a wide ranging question but any advice, especially from someone who has gone this route, would be greatly appreciated.
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