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quote:
Originally posted by cabipe:
Any One who runs 351c with 4X48 IDA, who can provide me with a good calibration on those
carb. fore a 351c 10:1 comp. 300 mech. cam.




The most important factor in Weber tuning is sycronization. Use 4 calibrated vacuum meters
so you can monitor the vacuum during operation.

If you use an air cleane, the aircleane MUST
include the air jet cavity between the air horns. NEVER put an air cleaner only on the stacks. If you do you got an emulsion tube barometric pressure missmatch via the venturi channel, and the engine will run terrible rich.
Try this jetting. Emulsion tube F-7, main jet 145, air jet 160, low speed F-10-60.
Venturi 42, long boosters.

It works like this. Low speed up to 2500 rpm.
2000 and up is the main jet area.

If you want the engin richer at only 6000rpm
go down on air jet. Or leaner at 6000 go up on air jet. This leaves the 3000 region undisturbed.

if you want 2000-6000 regiser richer go up on main jet. Or the reverse.

If you want richer 2000-4000, go up on main jet and air jet.

A thinner emulsion tube will richen the mixture from 2000 for the first sec of the acceleration. Tubes with the emulsion holes
low down will lean the mixture out after a few sec. Holes on top makes the main sating to work at once, or we can say leaning out earlier. Emulsion tubes takes experience so I dont recomend fiddling around with extreme tube dimensions.

Remember, if you dont get an IDA to work, dont blame the carburator. Sart thinking what to do, becouse there are no better carb.
You are also wellcome to ask.
Good luck!

Cheers
Goran Malmberg
To Gorans reply, I'll add a few personal experiences with Webers:
the exact jetting on any engine will vary wildly depending on the engine parameters, the area you drive in and what carbs you have. Weber built many variations of each type and by now, most have been thoroughly molested. I once sold a set for a Pantera (off a Cobra) that had one carb with a model # even Weber-Italy couldn't trace! Note 1- all the idle, main, hi-speed and acceleration circuits in a Weber carb interact to an extent, and there are 5 jets and two air-bleeds per cylinder. The cheapest replacement jet is about $5, so fumbling around in there can get very expensive. If you've never done these before, be prepared for a steep, frustrating $$$ learning curve. I'd go to a Weber specialist. Being poor, I did a full-power plug-chop in 3rd gear, uphill, on my way to work each day, then pulled one jet from each carb during lunch hour, soldered it up and re-drilled to a different size using a set of pin-drills I carried with me. Then I'd do another plug-chop on the way home. Once I had a size for that jet that worked well, I'd order a new jet of the size my drilling indicated was OK. It took me 6 months to get the things working right. Typical bolt-on Webers either run great but give 8 mpg, or run lousey & give decent gas mileage. Second note- do NOT let anyone talk you into running foam air cleaners on Weber carbs. Webers are always on I.R intakes & there are severe pulsation effects with IR intakes. The pulses also carry fuel OUT of the carb horns so gas saturates the foam. Webers always pop and backfire at low engine speeds especially when cold. This will often catch the gas-soaked foam on fire. I burned off two sets of foam cleaners before I wised up to using big paper air cleners, and worst or all, the aux venturies are zinc castings and will melt in a carb fire. Molten zinc runs down the intakes and with closed-chamber heads, there's not a lot of room inside if a valve happens to be open. The molten zinc quickly hardens & when I re-started the engine, it cracked a piston.... Third- Always carry a freon-type fire extinguisher when running Webers. A powder extinguisher caused almost as much damage to the car as the 1st fire did. Freon extinguishers are available from Pegasus Racing in WI. They aren't cheap but the powder clean-up & corrosion damage took me 3 days to overcome. Finally, be aware that the commonly-used 48 IDA carbs are undersized for a 351C, even with 4 of them. Each carb barrel flows about 220 cubic ft per minute of air to a single cylinder, while a Holley 4bbl on an open plenum intake flows 600-750 cfm to each cylinder. So typically, a dyno run will show a drop-off of power above 5500 with well-tuned Weber 48IDA-s, just like with a small Holley. Whats actually needed are 55 IDA-s, not very available even when Weber was still making carbs. You will likely need ignition changes too since its almost impossible to run vacuum advance with Weberr carbs- the pulses mess that up. A set of well-tuned Webers look & sound terrific on a V-8, but its like living with an exotic dancer IMHO....
Looking back on my first comment, it looks like an orgy in spelling mistakes and not so well planned descriptions.
Jack added a necessary reply.
I used my 4 48 IDA:s on a 302 motor. It pulled 427 hp at 6700 rpm. I cant tell what Hp could be had with the 48;s, but I am pretty sure 450 would be no problem.

I am a little stubborn, to say the least, and don�t throw the towel in before things are where they are supposed to be, so the 302 recorded 26 mpg at steady 60 mph driving. (No takeovers).

One must be deeply interested in carburettor tuning to get 4 IDA:s to function properly.
Otherwise one change face colour after a month.

If one dosent have "carb tuning" interest, one must be deepley intrested in looking for Weber experts. Otherwise one trashcan the carbs after a month.

Goran Malmberg
If you are planning on IDA's...those are stock at 48mm . I also looked into IDF's that as I recall are a little better for low RPM, I think they have an additional circuit. Depending on what you are doing you might also want to reduce them down to 44's or 42's. I ran 44's & 42's on a vintage McLaren with a 360 Chevy small block that was setup for the track. Although it had the best heads the Chevy racing division could come up with I'm not sure that they flow as much as a 351c port? On a 302 for the Mangusta you are going down roughly 16% in cubic inches you might want to go to 40-42's if they are available. It depends on what kind of driving you are doing.

They are fun to jet, learn as much as you can about the different circuits and have fun if you do it yourself...they are a blast once you get them close. You have to have the vacuum guage to set the individual throttle positions or you will never get them to work right. Buy a Webber drill set and have at it. For the Mangusta, there are quite a few 289's & 302 with that setup so you should have an easy time with them.

Here is a forum thread from a few years back that will probably help also:

http://pantera.infopop.cc/eve/forums?a=tpc&f=5650045562&m=9750043874

Check out this link:
http://www.gt40s.com/forum/gt40-parts-sale/26246-weber-...89-302-manifold.html

Someone is selling what looks like a full setup for a 302 that should work for the Mangusta for 1950 Euro...about $2500 US. Sounds about right and it says it already setup.
Last edited by tomsealbeach
To add to Tom's valid comments, IDF's are preferred for street and more tuner friendly. Specifically 44IDF's for 302's producing less than about 400HP. A complete set up of 44IDF's on a 302 manifold can be had for $1995 NEW. A good vendor will be able to set them up with the correct venturi's, jets etc. for your application.

quote:
Someone is selling what looks like a full setup for a 302 that should work for the Mangusta for 1950 Euro...about $2500 US. Sounds about right and it says it already setup.


Tom, those are 48's and recommended for motors over 400HP. They are also priced in sterling, GBP1950 which is around $3K US and way overpriced, but American performance parts in the UK or Europe fetch a premium.
quote:
Originally posted by Joules5:
To add to Tom's valid comments, IDF's are preferred for street and more tuner friendly. Specifically 44IDF's for 302's producing less than about 400HP. A complete set up of 44IDF's on a 302 manifold can be had for $1995 NEW. A good vendor will be able to set them up with the correct venturi's, jets etc. for your application.

Wow...Julian I'm taking you with me next time I go abroad to handle the money...I thought that was euro...oops....big big woops!
quote:
Someone is selling what looks like a full setup for a 302 that should work for the Mangusta for 1950 Euro...about $2500 US. Sounds about right and it says it already setup.


Tom, those are 48's and recommended for motors over 400HP. They are also priced in sterling, GBP1950 which is around $3K US and way overpriced, but American performance parts in the UK or Europe fetch a premium.
Otherwise one trashcan the carbs after a month.

Goran Malmberg[/QUOTE]

If anyone needs a trash can I'd be happy to play that role if you are heaving a set of 48's from you 351c. Webber's are actually quite a bit of fun to tune if know the basics but can be quite a handful when you get off track with them.

Make a "Carb changes sheet" and make very detailed notes on what you changed and what happened...take lots of plug readings at different rpm's(this is how I did it)...run the motor in gear for a sustained period (30 seconds)then turn off the motor and push the clutch in at the same moment you turn off the ignition. Coast to a stop...take a plug reading. Keep doing that until the plug is tan. Look at the RPM ranges Goran mentioned and that will be where to read the plugs and make changes. Its been many 15+ years since I tuned Webbers but remember it like yesterday. As Goran eluded they are great carbs but you have to have a ton of patients. If you are a tinkerer get them. Also do yourself a favor, take off the rear deck lid for all the tuning...it will give you the room you need and make it a lot easier for tinkering.

Dang it...why does someone(thanks cabipe) always have to bring up Webbers? I always want a set when I start reading the posts.
Not sure if you got a starting point for the Webbers?

I found this in my garage...it's the specs on the 48 IDA's I ran on the McLaren. It was setup with a 360 chevy small block with aggressively ported turbo heads...as I recall 2.02 intakes and 1.60 exhaust. My guess is these might flow close to what a 351c 4v head would flow.

42 chokes, Idle Holder 120, Jet 50F10, emulsion tube F7, top jet 140, bottom jet 185.

I don't recall if this is where I started or ended up...but it's a very good starting point and there wasn't a big mismatch from where I started and finished.
I talked to Tara at Hall a couple of months ago and they have the 351C 4V Weber intakes in stock for around $600 IIRC.

I also talked to Steven at Pierce and their pn K9110 351C 4V Weber set up is $3255.00. He said they use the Hall manifold.

There was a post some time ago about the Aus made IDF manifold for 2v or 4V heads but I don't know what ever happened with that.

I think Joules recently sold a Weber set up.

There are a number of Weber and IR EFI suppliers. Here is a short list of some. I don't know if all of them sell a 351C set up or not.


http://www.verycoolparts.com/weber.htm

http://www.webercarbsdirect.com/.

http://www.webercarburetors.com/

http://www.redlineweber.com/

http://www.piercemanifolds.com/products.htm

http://www.racetep.com/weber/v8webnew.htm

http://www.twminduction.com/

Here are more links where they have been discussed here on the PIBB

http://pantera.infopop.cc/eve/...220026183#2220026183

http://pantera.infopop.cc/eve/...562/m/8300093835/p/1

http://pantera.infopop.cc/eve/...562/m/6450019764/p/1
Last edited by pittcrew
Paul, Brooke,

A relatively new business called AussieSpeed Performance Products, based in Adelaide Australia, purchased the rights to the intake manifolds originally designed by John Cain.

The owner, Mark, being a small businessman has limited time and financial resources, he's going to focus his energy where the biggest demand is. He has made progress on the 351C Weber manifold at my prodding. I have actually seen his first casting. I expect to see this manifold go on sale sometime this year. I have kept quiet about the projects progress simply because if people get their hopes up, and then things don't happen as fast as they expect, they lose their enthusiasm & get pissed off. I don't want that to happen. So I have felt it is best to just lay low and wait for Mark to have them actually ready to sell. Just like in the case of Tod Buttermore's new 351C block, when you are dealing with entrepreneurs and small businessman, patience is a must.

The 351C Weber intake designed by John Cain was designed for 48 IDF carbys, not the usual 48 IDA like the Hall intake manifold. The IDA is a race carby, the IDF is a street carby. It is the better carby for street driven cars. Like the majority of Aussie 351C inlet manifolds this manifold is designed for 2V heads, but has enough metal around the runners to seal up against a 4V head. Mark was also in contact with John at CHI, there was some talk he would design an inlet manifold for the CHI 3V head. I don't know if Mark decided to follow through on that one.

IDF carbys feeding a small port 2V head will produce a far more satisfying level of drivability than IDA carbys feeding 4V heads. I think people will be quite pleased having this inlet manifold as an option for their Panteras.
The manifold in your link is the Redline Weber manifold. Its one of 3 manifolds Redline manufactures for the 351C. They've produced that manifold for many years. Redline's Weber manifold uses adapters that allow it to be used with either 48 IDA OR 48IDF Webers.

If you are considering 48IDA Webers, the Hall Pantera manifold is the better choice, there are fewer bolts & gaskets to worry about, and the carbys will sit lower.

If you are considering 48IDF Webers, be forewarned, the IDF adapters for Redline's Weber manifold are so tall that the IDF carbys will not fit below the engine screen. The Cain Weber manifold that AussieSpeed is working on will not have that problem.

Here's some pictures of the Redline manifold with IDF adapters taken at the office of Pantera International:



Here's some images of a Cain manifold:

quote:
Originally posted by Pittcrew:
... You must have quite a collection of Intakes at the PI HQ ...


I don't know of a die hard 351 Cleveland fan that doesn't have a collection of intake manifolds. Finding an intake manifold can be the hardest part of a 351C engine project.

I've been kicking around a new idea, instead of installing Webers on my Pantera, cutting down a Weiand Tunnel Ram to get the desired spacing of the runners, weld a mounting plate for a pair of Holley 4500 Dominator carbs on top of the runners, and use a pair of Dominators in an independent runner configuration. This is not an original idea, that was the set-up used by the Boss 302 Trans Am teams until the rules changed to make it illegal.

Here's the Boss 302 intake:



And here's what it looks like installed in a 'Stang:



Wouldn't that just make the Ferrari and Lambo guys crap their pants? That's the kinda outlaw, "wanna-race for pink-slips" set-up a cowboy from hell should have in his engine compartment, right? Smiler From my point of view, 2300 cfm of Holley Dominators is the bad-ass, American Muscle way to do independent runner carburetion.

I will of course still purchase the Cain/AussieSpeed manifold when it becomes available, because a fellow can never have enough intake manifolds.
Last edited by George P
Yea the plugs probably do hurt flow, but the light show makes up for it! applause

This is a great education of intakes. The independent runner vs. one carb feeding through a plennum is really interesting comparison. Thanks George.

I like the looks of the Webers much better than the two Holley's but I can tell you it sure would be allot easier keeping the Holley's in sinc. I was constantly futzing with the Webers and often wished I'd had just a single four barrel on that motor for an ease of use. George, have you run both the IDA and the IDF in the past on the 351C??? Whats the drawback on the IDF?
quote:
Originally posted by Tom@Seal Beach:
... Whats the drawback on the IDF ...


The ONLY drawback of the IDF is the linkage required to sync 4 carburetors.

The IDA being a racing carby, has two circuits, idle & main. No intermittent circuit. When racing you are either accelerating or braking, the lack of an intermediate circuit is not a problem. In fact, it was intentionally left out by Weber. Street cars are driven mostly at part throttle! With an IDA, part throttle operation is achieved by the careful blending of the idle & main circuits. The IDF has an intermediate circuit. Their part throttle performance can be tuned to be smoother and consistent day after day. They have been used as original equipment on Porsches (that I know of, perhaps others as well). Another benefit, the IDF is considerably smaller than the IDA, including height, and they will fit under the Pantera engine screen when the Cain manifold is used. The IDF also has standard air filters readily available. These are the carbys mounted on about a million Volkswagen baja bugs. Its also the carburetor used on most of the Chevy Weber carby set-ups.

I have never run either Weber on a personal car. I have installed them on other people's cars and then drove the car to someone else for tuning. Ask Kelly Coffield (Panterror), I am always teasing him about how much torture it is to own independent runner carburetion. But I won't deny it sounds bitchen, improves mid-range engine performance and the throttle response is unreal. I think Webers look "right" in a Pantera engine bay, so I'm tempted to install them on 6018. The only Webers I would consider installing on 6018 are the IDF's, never the IDA's. There's a big difference. Most people who install IDA's on their car eventually take them off. There's a few souls who remain loyal to them, and learn to live with their fussiness. But then, there's a few souls who sleep on beds of nails & beat themselves with chains too.
quote:
Ask Kelly Coffield (Panterror), I am always teasing him about how much torture it is to own independent runner carburetion. But I won't deny it sounds bitchen, improves mid-range engine performance and the throttle response is unreal.


Ah-hah! A concession if not confession from the Cowboy!!! This post has been saved to my favorites George.

Seriously though, tough to beat the practicality and performance of a 4-barrel, street or race. There is a reason they were/are standard equipment for so long before EFI. However, for striking that difficult balance and achieving a high state of streetable tune, I do like IR induction but freely admit, it takes some work to get it right. In fact, I have a link to a set of IR inlines in the parts for sale section. I know, it is a shameless plug, but George left the barn door wide open for me.

Take care,
Kelly
Last edited by panterror
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