Weber 34 ICT/ICH question

[60s Refugee]

So..OK..some of you guys like the Weber 34's. What strikes me as strange about that is that the 34 is a four cylinder carb, rated at around 150 cfm. I'm sure a VW or a MG might do better with one, but a 200 six needs about twice that much. If you have progressive linkage, how can the engine run right when just using the center carb? I have read in previous threads about the various 2bbl Webers, but I have also seen set ups with just the three 1bbl carbs. If the 34's will work, the price is right. If they don't then it ain't!

Harry

 

[Bort62]

If you are talking about tri-power w/ progressive linkage...

It's true that a 150 cfm carb is a little small for the 200 six... at WOT + high rpm.

At part throttle and low rpm operation (driving around down) a small carb will generally give great response as well as fuel economy.


That's the point of a progressive linkage. At part throttle, it acts like a 150 cfm carb... at WOT it acts like a 450 cfm carb.

Make sense?

You could idle one of these engines on a lawnmower carb... airflow is dependant on RPM and load.

 

[ludwig]

You could idle one of these engines on a lawnmower carb... airflow is dependant on RPM and load.

Man! That would be a look at the lawn tractor nationals: tri-power AMF.

 

[HighVolkage]

first of all, that rating is probably on the stock jets. if you go 34 series you will need bigger jets. secondly, like said above, you will mostly be running only center carb when cruising/idling. i check my plugs about every 2 weeks and i'm always in a good range.

good luck

 

[Bort62]

first of all, that rating is probably on the stock jets. if you go 34 series you will need bigger jets. secondly, like said above, you will mostly be running only center carb when cruising/idling. i check my plugs about every 2 weeks and i'm always in a good range.

good luck

Not sure how the jets, regardless of size, affects airflow capability

 

[60s Refugee]

You make sense Bort62. I didn't think about the other two opening up at mid range.
The two Holley 1921's I have are relatively low volume carbs too.

Harry

 

[HighVolkage]

first of all, that rating is probably on the stock jets. if you go 34 series you will need bigger jets. secondly, like said above, you will mostly be running only center carb when cruising/idling. i check my plugs about every 2 weeks and i'm always in a good range.

good luck

Not sure how the jets, regardless of size, affects airflow capability

haha good call. i was only thinking about fuel. derrrrrr its been one of those days

 

[grocery getter]

i'd go two carbs. block the stock hole. get a dual out header with two widebands. you will be able to fine tune it and have a very nice runner.
like addo mentioned in another post, put a separation plate in the stock hole. that's how i'd do it 8)

 

[mugsy]

So..OK..some of you guys like the Weber 34's. What strikes me as strange about that is that the 34 is a four cylinder carb, rated at around 150 cfm. I'm sure a VW or a MG might do better with one, but a 200 six needs about twice that much. If you have progressive linkage, how can the engine run right when just using the center carb? I have read in previous threads about the various 2bbl Webers, but I have also seen set ups with just the three 1bbl carbs. If the 34's will work, the price is right. If they don't then it ain't!

Harry

Remember that the flow rating is at some specified pressure drop. And we are talking about a carb and not a pump. A 34 ICT or ICH can flow more than 150 CFM, but it will be at a higher pressure drop.

The other issue is that our beloved 200s don't have the *best* volumetric efficiency. Assuming the convesion of chemical energy to mechanical energy is roughly the same between these two motors then why does my '98 Neon with a 122 cu in engine make 150 HP net at the fly wheel, while my trusty 200 cu in Ford make about 90 HP net? The Neon breathes a whole lot better (which mean more fuel too). The carb needs to be matched to the HP of the engine, and not just the displacement.