BXProject

[Philhod]

After reading this lot I would term it bordering on Demoniacle

[Way2go]

I dunno, I think less so than tuning and balancing carbs with water gauges etc as used to be the case. That was real Black Magic to get them sweet

[Philhod]

Used to use colourtune and a stethescope myself.....simples

[mat_the_cat]

I've never had trouble myself with balancing carbs (mainly on bikes) - maybe I've been lucky? That said I've never tried with more than two!

I like the fact that you could adjust things by tweaking a screw, changing a jet, or moving a needle - i.e. you could actually do something physical and see the effects. Fair enough, trying to jet a carb to give an optimum mixture over the full rev range is a compromise at best, and I think I would get a similar sort of enjoyment/satisfaction with a mappable ECU and laptop.

[Philhod]

One of the best carbs to tune is the SU of course. It reached it's peak on the Montego (bless it)

It had a stepper motor added, that altered the mixture across the rev range. Very succesful and trouble free and took the compromise away.
Strombergs were ok as well, same principle but a pain unless you changed the diaphragm, every time you took the top off.
The only way to tune the fixed jet type was to determine what type of use the car would mainly be put to and then select and fit the manufacturer reccomended jet pattern.

Bikes are generally easier to set up, they have a very short IM, usually one per carb, so doesn't destroy your set up with multi air dynamics.

[docchevron132]

I fucking love SU's, they really are the best carby of EvAh.

[Way2go]

They are good but I had some head scratching one time when the thing had a bent needle! Replaced the needle and it was as good as gold.

[Bx Bandit]

What's this stepper motor stuff then? As in, I know what a stepper motor is but what did it do? Adjust the needle seat? I also didn't know the mixture needed to be tweaked over the rev range!
I'd love to put throttle bodies (is that the right term - like one carb per cylinder?) on the valver! Is that what you meant on the bikes Phil?

[Philhod]

Err.. yes and no Bandit.
First bit, you are right about the stepper, it made automatic adjustments to the jet bridge as you drove.
Coupled with the swinging needle mod, it made the motor very economical in mixed use and also shortened the choke operation fron 7 to 4 mins.

The bike multi's have one carb per cylinder and are easy to set up because with a car, when carbs were used,
very few had a 4 branch IM. When the valves shut air/fuel comes back up interfeering with the flow you were setting up on the other carb (twin set up).

Throttle boddies are away of converting a single point injection system to multi, or with other gear, from carbs, as the boddies contain injectors. They just look like carbs a bit.

[Way2go]

Throttle boddies are away of converting a single point injection system to multi, or with other gear, from carbs, as the boddies contain injectors. They just look like carbs a bit.

They don't have to contain an injector (although that type are available) just the throttle butterflies. The GTi has a throttle body already which doesn't incorporate the injectors which are separately mounted closer to the valves.
If Bandit's idea of conversion were to be carried out, presumably smaller aperture throttles would be needed along with 4 airflow sensors in conjunction with an ECU that accepted the 4 input airflow information for optimum individual mixture control. A remapping game of a suitable ECU would then ensue. Only 1 TPS would be needed though as the throttle linkages would be ganged.

[Philhod]

Yes, I did say you would need other stuff

The throttle diameters are determined by the length of the IM and come with the conversion kits that are available now.

[Bx Bandit]

I've seen it done somewhere on the net to a 16v, but a mate had a courtesy Catheram whilst his was in for service which had the K series engine with the 4 throttle jobbies! Twas the R300, (standing for 300 bhp/tonne) which works out as 150 BHP in a 500kg car!

[Way2go]

Some of the sliding antics that Cateram drivers get up to are a bit wacky.

[Bx Bandit]

yeah but fucking cool! My mate mate let me drive it........I didn't go balmy cos I didn't want to be an inexperienced cock in a powerful car but I did pick up the revs and dump the clutch on a quiet T junction and got the back end out nicely - twas like being in the Dukes of Hazard!

[Philhod]

I helped build a Lotus 7 back in the late 60's and therefore got to drive it.

Absolutely awesome!! He used a 16v Dolomite engine... ( , must have been 1970), that had 2 SU HS4 carbs, breathing through 2 separate IM's. It was...err...very fast and dubbed the 4 wheeled motorbike.

The esuing Caterham/ Westfield's are blessed with even more power to weight, so must be sort of, entertaining??

[Bx Bandit]

ooooh tut tut! Don't mention catheram and westfield in the same sentence! The Catheram at least has ally panels, all pre-drilled ready for pop-rivets if you choose to make it yourself. The Westy has a horrible fibre glass shell with poor fit and needs potchy drilling and fitment...they look a similar beast but quality wise they are very different; the Catheram being better engineered!

I've only driven the one Phil and pretty cautiously, but I have been driven round a track on a few occasions much to my delight! You need not slow down at all for roundabouts!

[Way2go]

much to my delight! You need not slow down at all for roundabouts!

Yeah but, that artic already on the roundabout will be putting another sticker on its side much like they did with Sinclair C5's on Spitting Image!

[Philhod]

It'll go underneath

Well if we are talking kwalite I shouldn't have mentioned either of them in the same thread as Lotus

Caterham, like the lotus, are no longer available and I thought Westfield had bought the licence off caterham, who bought it from Lotus.
But I'm not sure.

The Lotuses (or is it Lotii), were mainly fitted with plates on the chasis, to bolt Fraud 1600 then 1700 crossflows to. I had to modify these to take the Triumph unit, which was far superior.
Unfortunately the g/box wasn't and I think he later managed to graft a Fraud single rail box to it.

[Bx Bandit]

Caterhams are still made Phil! The 80's/early 90's used either a ford x-flow or a Vauxhall unit. The vauxhall was heavier but had more torque. They use K series engines now but the odd nutter puts a motorbike engine in, the Honda Blackbird and Suzuki Hayabusa being the most common.
Ah, just realised, did you mean Lotus don't make the Lotus 7 any more.....Catherham bought the rights to the Lotus 7 when Lotus themselves stopped production

I wouldn't necessarily say that the Catherham is lesser quality than a Lotus, less refined yes, as they are more thoroughbred sports car.

[Way2go]

The best publicity ever for the Lotus 7 must have been the intro to Patrick McGoohans's "The Prisoner".