This one is for the Doc. I've been tinkering with my alloy head 200 hybrid Ford and got the carbs mounted.

These are two sets of 36mm Mikunis with the end carbs removed and grafted together into a six-pack. Tube stubs and flanges mount them to the engine.

I still need to hook up the fuel lines. So far I've only run it for as long as the fuel bowls have fuel, but it starts easy, idles nice, and has incredible throttle response. I'm looking for 250-260 hp at 5500 with the mild cam I have in it.

Seems like this would be easy to do on a Slant.....Poorboy's Webers!

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Jack Collins
66 Mustang 250 EFI
Lotus Seven Replica (Under Construction)
<img border="2" src="http://fordsix.com/locost/locostsig.jpg" width="275" height="118" >

Now that really looks cool Jack!
Great minds think alike, I picked-up a couple of sets of Mikunis at a swap meet, I'm not sure what size they are but hey, they were cheap.
(old motorcycle carbs)

Where did you get your set?
DD

What engine were the Mikunis on originally? I have a set of Keihn carbs from a KZ-1000 that I thought about trying on the slant. I looked around for another set and found some but I don't have time to fool with it right now. I have to finish the house remodel for the wife before I can play with my toys!

E-bay. I scored the two sets from 1100 GSXR's for $55. These things are dirt simple; rebuild kits are cheap. Needles, jets, and air correction jets. Idle mixture, idle speed. Get them synched and you're in business. Carbs, tubes, flanges, clamps and all, as you see it hooked up are under $100.

Here's a sound file. It starts immediately and the throttle response is phenomenal. I haven't got the cooling system hooked up yet, so I have to shut it off immediately, but it sure sounds good. Nice and lopey, but with a good roar thru the open headers.

http://fordsix.com/locost/locost.wav

According to some calcs and curves I've seen, these carbs will probably only take me to 5500-5800 rpm, but that matches the cam pretty nicely. IR systems require a LOT of carburetion.

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Jack Collins
66 Mustang 250 EFI
Lotus Seven Replica (Under Construction)
<img border="2" src="http://fordsix.com/locost/locostsig.jpg" width="275" height="118" >

Very cool Jack. . Is that the engine in your Lotus 7? Hmmm, some old slant manifolds, a welder, some fabrication....
Marc, a KZ1000.....

I went and measured mine. The KZ-1000 carbs are Mikunis. The Keihns are on the Honda 750. The Mikunis don't look like yours though. They measure 40 mm on the inlet side and 30 mm on the outlet side. How does that compare with yours?

5500 rpm would be more than enough for my taste. All I really want is good performance at freeway speeds. I figured if it ran good up through 4000 rpm it would probably do what I want.

I got a bug to play with an IR system and this looks like a cheap way to do it!

These have 36mm throttle blades. Not sure if that corresponds to a particular model.

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Jack Collins
66 Mustang 250 EFI
Lotus Seven Replica (Under Construction)
<img border="2" src="http://fordsix.com/locost/locostsig.jpg" width="275" height="118" >

How'd you go about shaping the pipe ends and bending them to fit right?

IMHO 30mm throttle way too small. 250" = 683cc per cylinder, could probably use a 44mm vacuum carb or 38mm flat slide.

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I made the tubes with exhaust tubing. I just did a cut and weld on some bends to get the right curve.

38mm flat slides would be just about right, but on a 200 (550cc/cyl) that should only rev to 5500, the 36mm carbs should work fine.

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Jack Collins
66 Mustang 250 EFI
Lotus Seven Replica (Under Construction)
<img border="2" src="http://fordsix.com/locost/locostsig.jpg" width="275" height="118" >

so what size(mikuni) would correspond with a 225 bored .030?

Well, everything I know about IR systems is in David Vizard's book "How to Build Horsepower, Carburetors and Intake Manifolds". He gives a formula to calculate venturi size and of course it also varies with RPM. Using his formula and 5400 RPM you would need a venturi size of 36 mm. Venturi size should be around 80 per cent of bore size or butterfly size. That would make butterfly size about 45 mm.

Again that's what Vizard says. I personally ain't never been there nor done that but I want to try it when I get some time.

A guy could cut the ends off an aluminum slant manifold, to make some stubs with, and weld on some suitable tubes to attach the carbs to.... kinda puts a new light on those junkyard aluminum factory manifolds I've been ignoring...

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It's a Slant thing. Even I don't understand.

1974 Duster, EFI /6 soon to be turbo...

Get that Monkay! Get that nasty thing!!

That's an interesting cross-flow Ford head. Would like to have one like it for the slant six.

I tore down a '80s BMW 7 Series motor in the salvage yard(it was already
mostly apart). The bore center spacing is pretty close to a slant six(close but not that close). It is interesting as it has very short ports which aren't very much larger than a stock slant six, valves were about as large as you could put in a stock slant six head, about 1.74" intake, valves were canted as in a Hemi layout). This particular BMW is two-valve closed chambers with some quench, makes less than 200 hp, but it was only a 3.5 liter, comparing very well to the 225. Intake ports were round, exhaust were squarish, single OHC. If that basic layout could be adapted for pushrods it would work great. Not big valves, but apparently very well flowing, short and smooth ports, valves had some room to grow.

I just got a brainstorm from using bike carbs. This same approach could be taken with individual throttle bodies from a FI bike, and use Megasquirt. Mustangsix, did you try to calc the correct length of the intakes for a specific RPM? How did you handle throttle sync?

Good job! It is really interesting.


Greg