webers

windsor · 12-05-2003

I am wanting to change my quad 44 idf's to 48 ida's
Will I notice any difference in hp or torque?

GTRaptor · 12-09-2003

Tell us more about your setup and mods.

windsor · 12-09-2003

the engine is a 347,10.1comp,comp cams 294s,alloy windsor snrs,
1 3/4 headers,tremec,4.1 rear

it made 369rwhp, in a 68 mustang
and some head flow figures......
Intake cfm Exhaust cfm
67.2@0.100 57.8@0.100
139.4@0.200 117.2@0.200
197.9@0.300 151.9@0.300
243.4@0.400 185.6@0.400
275.1@0.500 193.7@0.500
298.1@0.600 203.2@0.600
309.2@0.700 209.2@0.700

TobyBall · 12-18-2003

Which heads, valves, and combustion chambers?

What are you using as your redline?

Man, that pic of those webers in that other thread looked trick.

Will ask my carb expert...

windsor · 12-18-2003

Which heads, valves, and combustion chambers?

alloy windsor snrs, 64cc chamber.valves 2.02 inlet 1.6 exhaust(manely stainless)

Rev limiter set at 6700rpm but it lays over around 6000 and bit

Caprimaniac · 01-01-2004

At last!

Another person running webers! I've been looking in all(?) Ford SMBF- forums without any luck.

I run 48 IDF's on my 302. It has a 306 deg cam, and will soon have new bottom end withe 10,5- 11 :1. I now run on something like 9:1, and the setup works good.

It was interesting to see your rwhp- numbers etc. At what RPM was max hp? I'm really curious how my engine will run when it's finished.

My setup will pull til 7 k,according to Comp cams, and the revlimit will be around 7300.

I'm not sure, but I think you'll have to change manifold to switch from IDF's to IDA's- different bolt- pattern?

The IDA's should have some advantages over the IDF's, but it's marginal. On the other side, they have no cold- start system (choke).
May be better flow pattern because of better shaped inner walls in the barrels. They have better main axles and accelerator pump mechanism.

Also, a change from 44 to 48 mm barrels might give some more in the upper region. But: According to Mr. Passini's weber- book, the main venturi diameter (carb size) for an engine with 700 ccm/ cylinder (approx. 5.7 litres enginevol.) and power peak at 6300 rpm should be 43- 45 mm.

Maybe you'll experience less driveability in city traffic with the 48's?
(I have no means of comparing with my setup. My car have been used very little- it got the plates on just before the snow started falling...)

I think there will be very small gains in HP with the IDA's, maybe noticeable.

RS

Caprimaniac · 01-04-2004

For the sake of being honest- I've read the Weber- table wrong, again.

The table shows the OPTIMUM MAIN VENTURI SiZE, not carb size, for a given displacement and RPM.

Which means: Yes, you will gain some torque and hp by dhanging from 44 to 48 carbs. I can guess about 20 hp.

You probably have something like 36 or 38 main venturis now, and will move up to 40 or maybe 42 or 44 whrn moving up to 48's.

That will give you better readings at the top end. For sure. (you will also keep the driveability.)

RS