Carb/Intake questions

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lillbush

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Feb 27, 2007
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Hello everyone how are we doing today? Well I have a few questions here about my carb and intake. I have a 1990 Sunbird Corsair 185 with a GM/OMC 4.3L 262. I got the boat a few weeks ago and have been going through it all making lists and getting things done. The problem I am having is I am in the middle of rebuilding entire motor (new bearings, rings, pistons etc...) When I got the boat the carb was MIA and the original intake has been changed over to an Edelbrock Performer 2111. What do I do? What carb do I need? Can I use this intake or do I need to get a OEM? What Carb will work with my set up? I am still a little wet behind the ears when it comes to carbs and such because I am used to EFI. So please give me your thoughts as to what I should do.

Thanks
Matt
 
Scott Danforth

Scott Danforth

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Re: Carb/Intake questions

if your in fresh water, nothing wrong with running that intake. you need a marine carb, about 600cfm.
 
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lillbush

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Re: Carb/Intake questions

There is nothing else done to the boat/motor other than the intake manifold. Like I said I have it all torn down now and replacing all pieces inside with stock. Ok that carb looks and sounds like what I need. I know this might be a stupid question but...what is the difference between a marine carb and an automotive carb?
 
Lakes84

Lakes84

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Re: Carb/Intake questions

Well sir, I'm going through the same thing. I have an 87 OMC Cobra with the Cobra outdrive, so we have the same setups.

I'm replacing my 4.3 with a new crate GM 4.3 from Michigan Motorz. They specify if you have a pre 91 OMC you MUST use the Holly carb and not the Edelbrock. Unless you go with a Rochester Qjet, although that carburetor, while good I have been told to steer away from them. Why can't we use the Edelbrocks? It has something to do with the linkage on them and how they work with the Cobra shifting. Don't ask me why, I'm not a mechanic, but that is what Loren at Michigan motorz told me, plus it's on their website. I asked this question in another thread and no one answered, so I'm assuming most might not know why. The Holly linkage can work both ways I guess and the Edelbrock only one....not sure why, but it is what it is. If anyone can do a rebuttal as to how we can use an Edelbrock, I/we are all ears.
 
Scott Danforth

Scott Danforth

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Re: Carb/Intake questions

automotive carbs go boom on boats
 
Scott Danforth

Scott Danforth

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Re: Carb/Intake questions

the question from the OP was what is the difference between automotive and marine carbs (last question in post #5). without going into the details of fail-safe accelerator pumps, j-tubes, alternate gasket materials, different power valve ratings, or the myriad of other safety items that differ a marine carb from an automotive carb - it was easier to simply state the outcome.
 
Lakes84

Lakes84

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Re: Carb/Intake questions

Scott Danforth said:
the question from the OP was what is the difference between automotive and marine carbs (last question in post #5). without going into the details of fail-safe accelerator pumps, j-tubes, alternate gasket materials, different power valve ratings, or the myriad of other safety items that differ a marine carb from an automotive carb - it was easier to simply state the outcome.
Click to expand...

Sorry! :facepalm: You're right, I need to read a little closer! Matt, the Holly 4160 marine carb was what was recommended to me. There might be others to choose from, but I think that's what I'll go with.
 
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lillbush

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Re: Carb/Intake questions

hmmm well all this is great. Lakes84 I sent you a message. I guess I will look into a holly carb and even consider going back to a stock intake and carb setup. Does anyone have a carb for sale?
 
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lillbush

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Scott Danforth

Scott Danforth

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Re: Carb/Intake questions

your boat, buy what you want. however remanufactured carbs are a crapshoot

if it was my boat, I would put in a different cam, swap over to vortec heads, change the intake to a vortec and use either a Holley 4150 with a 2" spacer, or an Edelbrock with a 2" spacer. then again, thats me.

if your not inclined to do all of that, the intake you have is a step up in airflow from the stock cast iron piece - I wouldnt replace it with stock.
 
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ericga

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Re: Carb/Intake questions

You can match the performer intake with an Edelbrock 1409 marine carb + calibration kit 1485. I got a re-manufactured 1409 from National Carburetor for about 225$. Kit is about 20$. Carb I received was like new.
 
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ericga

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Re: Carb/Intake questions

... and before changing a carb/intake combo make sure you have enough height clearance.
 
Lakes84

Lakes84

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Re: Carb/Intake questions

As i mentined earlier. The Edelbrock carb will not work with a pre 91 OMC outdrive. My mechanic verified that with me. The OP is stuck with either a Rochester or Holly as explained above. Just trying to keep us all on the same page!;)
 
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ericga

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Re: Carb/Intake questions

True. Merc throttle is pull to open while OMC is push to open.
 
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ericga

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Re: Carb/Intake questions

Check National Carburetor -> All marine carburetor -> All four barrel rochester they tell you which ones fit the OMC linkage. I would call them with my engine model number to confirm it would fit.
 
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Gpayne

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Re: Carb/Intake questions

If I could chime in with my $.02, 600 cfm is way too big for 262 cubic inches. A 390 cfm would be a much better match. I'm not sure if Holley offers one in a marine configuration, but a 600, even a vacuum secondary would drown that V-6. You could jet it down, but if you go too far you risk leaning out the fuel/air mixture and melting a piston. A good rule of thumb is that if you have to go 3 jet sizes in either direction, it's time to consider changing the size of the carb. There's a mathematical formula commonly used by engine builders to figure out what size carb will work best on a given engine size. Unfortunately I can't find it at present, but I've used it in the past, and even a 350 ci. Chevy running at 85% volumetric efficiency only needs around 580 cfm to perform just fine. Of course, higher rpm's will help a smaller engine run better with a larger carb, but with max WOT being somewhere around 4500 rpm, I think a 390 vacuum secondary would be a perfect match to a 262 V-6.
 
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