Random musings on carb sizes, bike vs car

[Craig380]

I recently had the enormous pleasure of driving a Jensen Interceptor for a weekend. While poking around the engine bay, I lifted the air cleaner and had a look at the Carter 4-barrel carb.

It struck me that the two primary throats seemed to be smaller in diameter than the 24mm carbs on my 380, and the secondaries only just larger. And that's for a 440 cui mill.

[Alan H]

Remember revs different and 2 stroke will need more air and fuel than similar capacity 4 stroke.
Do the maths and work out actual air/fuel requirements.
I have a 500cfm 4 bbl Weber on my 4.6 litre Rover V8 and it ran very well.
I love V8s as much as 2 strokes!!

[Craig380]

The Jensen used a LOT of fuel, I can tell you that much: 20 gallons for 275 miles = 13.5mpg (Imperial).

Mind you, the 380 does maybe 45mpg, has an engine capacity 20 times smaller, weighs 10 times less and only has to drive one wheel

[Alan H]

Both lovely though aren't they?

My V8 was in a 1969 Landrover which used to upset lots of the local GTi brigade, a proper 'sleeper'.
0-60 in about 8.5, 3 speed auto so, 65, 105 and off clock!
Best fuel was 20.5/imperial gallon, worst was about 8mpg.
I loved it to bits and still have the engine in the garage.

[Craig380]

Bit of a beast of a motor, that 4.6 job. Was it from a Range Rover originally?

The Jensen has been my dream car ever since I saw my first one, aged 8. I did wonder if actually driving one would be disappointing compared with the dream: but it was everything I hoped and more.

It was as docile as a guide dog when pootling around town, but poke that throttle and it was like being launched from a giant catapult, it's the only way I can describe it. And that exhaust note. The mid-70s Chrysler 440 engine was probably only putting out 250-odd bhp with all the emissions-related detuning but they're shire horses, not pit ponies

[Alan H]

Yes, originally a RR. I only bought the bottom end and had a lot of work done on it.
Stage 1 heads, Piper hi torque cam, Weber 4bbl carb, duplex timing chain, hiflo pumps, twin point diz, block crack tested, crank balanced, rings and mains. T'was my baby!!