Hi guys, I'm looking for someone with experience of putting 4 Weber 48IDAs on a 401 nailhead. I initially spoke to Jim Inglese when I was buying my carbs from Weber in the UK. He said to put 38mm chokes in them, but after fitting, it looks like it needs way more air. It was running super rich and choking up. I went to 42mm chokes, but it still is very rich. I'm now looking at 46mm, but I wondered has anyone done this before and what did you end up with? My full spec is 401 Nailhead bored 60 over with a TA 25 cam. Running a built TH400 with a Hughes 200orpm stall converter. Gear Vendors overdive behind that. Winters Quick change rear. Webers have the following inside 70 idle jet / 1.00 or .90 idle jet holder, depending on what the engine wants F11 emulsion tube 155 main jet / 200 air corrector Stock .50 pump jets Zero pump bypass valve And it all looks like this
Looks cool. I have a couple of those on my dune buggy, hard to set up but good running when they are. Those air cleaners, do they just pop on top of the velocity stacks?
Might try a Volkswagen forum. Those guys use 48 IDAs all the time. How rare is an IDA intake manifold for a Nailhead?
Nice setup @EvilGus When was I building an off-topic car with Webers, I gathered tuning info from GT40 site. No practical experience to share because I sold my project before completion. Weber 48 IDA setup. | GT40s
My experience with Webers are with VWs, but the same applies to your engine. To begin with have you tried taking of the velocity stack filters? The look VERY restrictive. Most likely that's why it's running so rich. Also most times it's a lot harder to tune with velocity stacks than with regular air filters. I think Jim Englese was spot on with the 38mm choke recommendation. A 60 over 401= 845cc/cylinder. Choke size x 4 = main jet. So 38 x 4 =150 main jet. Air corrector size for a mild engine using IDAs should be about the same size as the main jet. For IDA carbs with 38 chokes you would want F2 or F7 emulsion tubes, F7 would propably be better for a mild engine like yours. Idle jet looks good at 70. Well that should provide a good starting point. A wide band lambda sensor would help with tuning, but it isn't tradional so i won't mention that .
What pistons did you use? It appears that there are composite head gaskets, how much was machined off the deck? When I put a TA-25 cam in mine, I had to advance it 3 degrees.
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