Ever had an itch you just want to scratch but can’t?

[AK260]

Thought this may make a good theoretical discussion.
 
While I have far to little time to do the inordinately long list of jobs on my Z (and with school fees ramping up spare cash is drying up fast), I just can’t help think one day I really want to do a triple DU6 conversion!!
 

 
 
Just imagine having the only z in the world with these puppies on!!! How cool would that look when you pop the bonnet!?
 
It will need a LARGE balance tube to even out the pulses (which somewhat negates benefits of individual throttles).
 
My only thought is that the best way to feed the vacuum signal to all carbs but without causing cross carb fuelling is to feed manifold vacuum in at the top of each dome. Just daydream engineering! ;)

[Patcon]

Were they ever used as multiples on any vehicle?

[AK260]

Having researched it a bit more - it seems that they were used mainly for racing and on the Coventry Climax engines (in twin format).

Lotus had also used them (as they used the Coventry engines) but very shortly - they ditched them for DCOEs.

Apparently they work well over 4k rpm and had quite an on/off characteristic. But as DCOEs came into popularity and were more flexible / easier to set up, the twin choke SUs were left on the shelf.

Folklore says around 80 were ever made. A UK based company is reproducing them again at a juicy price.

So, that itch no longer needs scratching, back to school fees. ;)

[Patcon]

I was wondering if they were used in multiples on other cars, did they mess with a balance tube?

[AK260]

I was wondering if they were used in multiples on other cars, did they mess with a balance tube?

That’s a great question on balance tubes - not sure. I know Coventry engines used them in multiples and mainly in racing but I found no tech info on balance tubes etc.

Interestingly, a member on the TR Register recently had them professionally fitted to his TR 4 (in multiple form) and found 8bhp more at the wheels compared to DCOEs. But again no useful info was divulged.

The trouble with most engines these were fitted to (as far as I’ve read) was that they were smaller engines that didn’t produce enough vacuum to lift the pistons sufficiently. Hence why they had a reputation for only operating properly at over 4k rpm - in racing applications.

I think we should all just get ITBs + stand-alone ECU and get on with our lives :p - did I just swear?

[jonbill]

8hp more on a TR4? Thats what, 50% more horsepower?