426 Hemi Gen II with 48 ida Webers Carbs

[jobenz]

Morning Hemi guys, anyone have any experience with running weber carbs on the 426 hemi street version??? Thinking about doing my car but really need to know the ins and outs of doing it. Any help would be greatly appreciated.
Joe

 

[Photon440]

Do you have the intake for that, or planning on fabricating a custom one? Keith Black used to sell that style long ago, pretty hard to find now.

 

[jobenz]

Do you have the intake for that, or planning on fabricating a custom one? Keith Black used to sell that style long ago, pretty hard to find now.

I have a brand new Keith Black manifold.

 

[Jeff Peterson]

 

[Geoff 2]

I have four 48 IDF Webers on my 455 Pontiac. Been on about 18 years. Back in the 80s, I had the Webers on my 440. Both were home made intakes.

The IDA carb is less street friendly than the IDF because of the idle cct. I would use the IDFs if possible, but the mounting pad is different.

Throttle response is unbelievably good & fuel economy [ if it matters ] is good if you drive with a light foot. Haven't measured exactly but about 12-14 miles per US gal city driving, much more on a trip.

Weber 'tricks':
- no more than 4 psi fuel pressure or they will flood. Use the Carter 4070 elec fuel pump
- they have small needles & seats, steel tipped needle. You will need larger n/s [ 2.5mm ] for a big engine. Redline in Hollywood Calif sell Viton tipped n/seats, much better. I adapted Carter AFB n/seats before I was aware of this!
- float level is critical, all carbs must be the same.
- large engines will require minimal throttle opening at idle/low speed cruise. So it is vital that the t/linkage has no slop in it. I did not like what was commercially available so I made my own linkages using small ball races & Heim joints.
- because of the large intake ports on the Hemi, the IR system will really wake up the engine.

 

[Photon440]

Just for comparison, Shelby raised the 271 hp. 289 up to 306 hp. in the Shelby Mustang. But with four weber carbs, got the power up to 385 hp. for the Cobras.

 

[Geoff 2]

I have an original article on the Keith Black 426 Hemi/Weber combo; it claims it made 150 hp more than 'stock'; stock I presume means the Street hemi.

 

[jobenz]

I have an original article on the Keith Black 426 Hemi/Weber combo; it claims it made 150 hp more than 'stock'; stock I presume means the Street hemi.

Morning, could you send me that article or post it if possible?

 

[Geoff 2]

The book is in too fragile a state. There is not much info on the carbs [ no jetting info ], mainly what was done to the engine.
David Vizards How to Build HP, vol 2 [ SA books #52 ] has a lot of info on Webers.
Gene Berg enterprises used to make 58 IDAs. On a 427 Ford, they made over 700 hp.