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Author
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Topic: Weber carburetor conversion
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georgeb
Gearhead Posts: 927
From: Solomons, MD, USA
Registered: Jun 99
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posted 10-28-1999 08:45 AM
   
I know Alex will probably think I'm nuts, but I think I'm gonna get a Weber wet up for my planned Shelby motor. Something about opening the hood and seeing four 48 IDAs (like the competition COBRAS) appeals to me almost as much as an 18 year old nymphette at the Dairy Queen on a Saturday night. Anybody had any experience with 48 IDAs on a small block Ford? Or seen a good magazine writeup? If not, I guess I'm gonna feel my way into it. Or maybe someone with a 289 COBRA R model has info on the jetting...
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deke
Gearhead Posts: 1573
From: Silver Spring, MD, USA
Registered: Jun 99
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posted 10-28-1999 08:50 AM
George,Is there a preformance benefit i.e. better throttle response, or is this just an exotic setup for difference's sake.... Sounds like an interesting project. vive' La differance!
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georgeb
Gearhead Posts: 927
From: Solomons, MD, USA
Registered: Jun 99
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posted 10-28-1999 11:00 AM
Deke: There SHOULD be a performance boost - better fuel atomization, equal distrubution to the cylinders, and an accelerator pump for each cylinder. My guess would be a 10 percent improvement over a properly sized/tuned Holley 4V.BUT - Lee Holman (Holman & Moody) says that a properly set up Holley will make more power, in his experience. I also have an acquaintence (can't remember his name...) in Dallas who built some AWESOME Ferrari twelve cylinder engines, and he also claimed that the best HP he'd seen on one of his twelves was with one BIG Holley 4V. Oh, well, it's not the destination, but the journey that's interesting...
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georgeb
Gearhead Posts: 927
From: Solomons, MD, USA
Registered: Jun 99
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posted 10-28-1999 02:15 PM
Well, what I'm gonna do is first put the long tube headers and a decent exhaust system on the 350GT; then do a tune-up; then do a chassis dyno reading. Yeah, I know the rear wheel dynos aren't that accurate, but what we'll be concerned with is a comparison.On with the new manifold and carburetors; tune the carbs for correct venturi size, stochiometric mixture and pump shot; then do another chassis dyno reading. As long as temp/humidity is about the same and tire pressures are the same, should get a reasonable comparison between the Holley 4V (4150, list 3259-1, 715CFM), and four Weber IDAs. I'd like to say this will happen soon, but it'll probably be next spring before I can get around to it. Stay tuned...
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Moneymaker
Administrator Posts: 26813
From: Lyons, IL, USA
Registered: May 99
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posted 10-29-1999 01:27 PM
George, single Holley and good intake will definately make more power with todays camshaft profiles. But nothing beats the "looks" of those 4 Webers under the hood! Have you ever heard of Inglese performance? He is the formost Weber authority that I know of.  Alex------------------
Alex Denysenko Co-Administrator and Moderator
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georgeb
Gearhead Posts: 927
From: Solomons, MD, USA
Registered: Jun 99
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posted 10-29-1999 01:46 PM
Yeah, Alex, I've heard of them; he even advertises ocassionally in the some of the Mustang magazines. It's my understanding that you tell him what you want (engine specs, etc.) and he sends you the setup to match it - BUT - someone told me his company files (or grinds) the numbers off of all the jets they install in their Weber 48IDAs. Don't know if this is true, but if it is, I think I'll get my Weber set-up elsewhere.Sounds like Jon at Pony Carbs - "Yeah, we made some changes to your 4150 Holley internals but we won't tell you what they are.", which means different gallery sizes,
stuff drilled and brass plugged, somewhat different float level settings, and power valve rated 3 sizes lower. I mean, what if I want to make jet or emulsion tube changes? Kinda hard to decide what you may need if you don't know what you've already got.
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Moneymaker
Administrator Posts: 26813
From: Lyons, IL, USA
Registered: May 99
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posted 10-30-1999 12:19 AM
Sounds like it's time for a little trip to Italy for parts George! Alex------------------
Alex Denysenko Co-Administrator and Moderator
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SteveLaRiviere
Administrator Posts: 44935
From: Saco, Maine
Registered: May 99
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posted 10-30-1999 01:47 PM
Those Weber set-ups really look cool.I remember seeing a set-up for a Pantera in an advertisement. I think they were gold plated on the air horns, they wanted about $2800 for it. My heart almost stopped. ------------------
SteveLaRiviere/Administrator Mustangsandmore.com Cherishing the Past,
While Racing into the Future!
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georgeb
Gearhead Posts: 927
From: Solomons, MD, USA
Registered: Jun 99
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posted 12-08-1999 02:44 PM
The deed is done - ordered 4 new 48 IDAs with basic 289 jetting and intake manifold (with thermostat housing) and linkage from Sweden, of all places. "A mere bagatelle" (W. C. Fields) at $3,200 which at least included shipping and insurance. At that price, a Swedish blonde should hand deliver the darn things. Customs will take a nip out of my hide, too.If you see me sitting on the street corner with a cup in my hand, please drop your spare change in the cup... But then, I also took a flyer on a discovery well in Texas on about 400 acres. If it's a dry hole I'm toast for awhile, but if it makes a well I'll probably be more obnoxious than usual and buy a 429 Mustang or a 289 Cobra. Ciao, George
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georgeb
Gearhead Posts: 927
From: Solomons, MD, USA
Registered: Jun 99
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posted 01-17-2000 04:47 PM
Unpacked the four NOS humongous 48IDA's and stared at them for about an hour. These were made about 15 years ago and have been sitting in the boxes.My, my, grandma,what big throats you have.The funny thing is that the four of them don't weigh much more than one Holley 4V, list 3259-1. Now all I have to do is make sure all passages are clean and clear, float levels correct, etc. I've ordered a different manifold and linkage (COBRA); then comes a first blood installation attempt on the Shelby 350GT. Of course, the brakes will go from booster assisted to manual (no vacuum). One way to keep the vacuum boost is to tap into each port from the BOTTOM of the manifold and run eight (or four) S/S lines to a junction block underneath, then a fitting up through the manifold like the standard vacuum fitting. Oh well, no rest for the wicked...
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I65Stang
Gearhead Posts: 6508
From: Folsom, CA
Registered: Jun 99
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posted 01-18-2000 01:25 PM
Wow, cant wait to see picks when you get it installed. I saw on Speedvision a 67-8 (been a while) fastback with the Inglese inducton that was running on the flats in Australia. They didnt even show the car run and I was still impressed when he took the blanket cover off the top of them (he had a problem with the carbs limiting his speeds). I dont care if the car would even run at all, sitting there it would look cool enough :>). Tim
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mustangs68
Moderator Posts: 24577
From: Buckroe Beach Va MCA#39406 M&M #12 Member Mustang Club of Tidewater
Registered: May 99
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posted 01-18-2000 02:32 PM
I can't wait for that Silver Spring Show...be ready by then George?How about VaBeach in May..I want to see that set-up!
sam
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MLariviere
Moderator Posts: 4065
From: Biddeford,Me.USA
Registered: May 99
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posted 01-18-2000 09:08 PM
Hey GeorgeB, how do you begin to calibrate such a complex setup???? Do you run a vacuum guage to each carb???? 
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georgeb
Gearhead Posts: 927
From: Solomons, MD, USA
Registered: Jun 99
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posted 01-19-2000 10:11 AM
Some Webers have vacuum ports for use with gauges or mercury columns, but the 48 IDAs don't. A Unisyn is the easiest way; we used to use a Unisyn to sync Su carburetors on various English cars.The toughest part of this installation will be air cleaners that incorporate the velocity stacks, breathe well, and still clear the hood.
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Moneymaker
Administrator Posts: 26813
From: Lyons, IL, USA
Registered: May 99
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posted 01-19-2000 03:27 PM
I can't wait to see it George.  Alex------------------
Alex Denysenko Co-Administrator and Moderator
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MLariviere
Moderator Posts: 4065
From: Biddeford,Me.USA
Registered: May 99
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posted 01-19-2000 08:43 PM
Not to sound green,George,But what's a unisyn? Rande,keep quiet!
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georgeb
Gearhead Posts: 927
From: Solomons, MD, USA
Registered: Jun 99
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posted 01-21-2000 10:49 AM
A Unisyn is a variable venturi vacuum "gauge" that has a visible cylindrical window with a float in it. You put the guage over the carb inlet (it has a rubber gasket/seal), adjust the gauge venturi until the float is at an index spot in the window, then move it to another carb and see if the float reading is the same. If not, you adjust the offending carb throttle opening until you get the same float reading on the Unisyn.The window is mounted on a pivot so that you can use the gauge with horizonal or vertical carbs.
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MLariviere
Moderator Posts: 4065
From: Biddeford,Me.USA
Registered: May 99
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posted 01-22-2000 02:18 PM
Thanks georgeB. I think I saw one before at a snowmobile/bike shop.
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