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post #1 of (permalink) Old 11-13-2002, 01:26 PM Thread Starter
 
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Aluminum 2bbl intake modification question

I recently switched to the MC 2100 and put an aluminum 2bbl stock intake on. As most of you know the MC2100 has larger "holes" (technical term escapes me) at the baseplate than the carter. I was thinking of milling the manifold to fit the larger "holes" of the MC2100. Also eliminating the 2 separate chambers and making one oval shaped chamber.

any thoughts ?
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post #2 of (permalink) Old 11-13-2002, 01:46 PM
 
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Re: Aluminum 2bbl intake modification question

Blending the openings is in my plans as well. I have a spare manifold and plan to do it with a die grinder. Not sure that removing the metal between the two bores would make much positive difference. After all, the air flow is limited to the bores. Continuing those bores further down should't hurt (??).I'll have to do a "mock up" and see if there is any interference. I'm working on a megasquirt efi computer and plan to try out either a motorcraft tbi (which bolts right in place of the mc2100) or a chevy tbi (will have to make an adapter as the howell adapter is kinda overpriced).
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post #3 of (permalink) Old 11-13-2002, 05:31 PM
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Re: Aluminum 2bbl intake modification question

I wouldn't remove the divider without knowing why. The engine designers probably didn't put it there on a whim. If you don't know why it's there, you can't predict what will happen without it.

You might screw up the idle, or make the engine run rich, or lean. You might make it a little stronger at the top end, at the expense of torque lower down. Or vice versa.
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post #4 of (permalink) Old 11-13-2002, 05:48 PM
 
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Re: Aluminum 2bbl intake modification question

I sure would like to know where you got a factory 2bbl ALUMINUM intake?

My race car buddys regularly grind that divider out of the chevy intakes, since they have to run stock intakes they are pretty limited, they all hog them out as far as they can reach, and cut that divider down to just a slight ridge above the bottom runner.

they want different results than us in an offroad engine (they goto 7000+ RPM)

I wouldnt get carried away or expect too much tho, I dont think youll spin the RPMS enough to really utilize any more CFM, but I dont really think itll hurt anything either.

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post #5 of (permalink) Old 11-13-2002, 06:24 PM
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Re: Aluminum 2bbl intake modification question

I don't know what it's out of, but there's an AMC 6 with an aluminum 2-barrel manifold in a junkyard near me. At least it LOOKED like aluminum - everything else was rusty.
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post #6 of (permalink) Old 11-13-2002, 06:47 PM
 
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Re: Aluminum 2bbl intake modification question

oh yeah DUH, silly me

he is talking abotu an inline 6.

I was thinking V8, IM not dumb, just a really SLOW learner! hehe

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post #7 of (permalink) Old 11-13-2002, 06:59 PM
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Re: Aluminum 2bbl intake modification question

Better watch out! You won't have any stars left either [img]images/graemlins/tongue.gif[/img]
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post #8 of (permalink) Old 11-13-2002, 08:27 PM Thread Starter
 
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Re: Aluminum 2bbl intake modification question

What would you think about just opening the holes to 1.08" and leaving the dividers to match the bore of the carb?
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post #9 of (permalink) Old 11-14-2002, 01:13 AM
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Re: Aluminum 2bbl intake modification question

4, 6 or 8 - samo samo.
It's divided to get better idle and low speed responce,
"snap" if you will. Improves torque a bit too.
It keeps the mixture flowing faster at the lower speeds,
keeping it atomized better.
Remember, it's pulsing.

If you are only concerned with top end - grind it out -
it helps there.
Notice really high performance manifolds - high speed stuff,
use just a huge plenum chamber, log type.
When you are making 1000 HP @ 8000, who cares about idle?

But, in any case, keep it smooth, no sharp edges or rough
stuff to cause eddy currents that restrict the flow.
Match the holes to the carb base. Enlarging the holes is fine.
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post #10 of (permalink) Old 11-29-2002, 07:52 AM
 
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Re: Aluminum 2bbl intake modification question

Ok, dug out the old aluminum manifold and gasket for the gm tbi to compare them, so that I can make an adapter. The jeep manifold has 1.5" holes that extend about an inch down into the manifold. The GM tbi has 1 11/16 bores, spaced much wider. I have thick enough material to make an adapter 2" thick to blend the two. If I keep the manifold divider in place, it's going to be a lot harder to blend the two bores. I notice the howell adapters are an open plenum type. What happens when the fuel mixture hits the divided plenum that has a flat top? Can't be good for smooth flow. I'm considering removing the divider from the stock manifold, and having the adapter create the two bores instead, matching the larger tbi's bores. I notice all the tbi spacers out there use two bores to match the tbi unit itself. Must serve some purpose. Well, I guess it does for the spacers, it avoids a gross mismatch by creating a plenum between the tbi and the manifold bores. Just that the two bores in the manifold are creating a mismatch between these two, unless I oval them outward and blend the ports thru the adapter. Was hoping to get away with less die grinder work and use more hole saw to keep the two ports symetrical! Any further thoughts on this subject?
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