1.2 Tuning - Realisticly, sensible thread!!

[meritlover]

and dont seem to appreicate how/why it works like it does.

[pyromaniac_yeti]

Motorcycle CV carbs have a butterfly and a slide, the butterfly opens as a throttle. The slide position depends entirely on engine vaccum thus doing away with any need for an accelerator pump. The carb slide position depends entirely on load, so as such the carb will only ever open up as much as the engine needs nomatter how hamfisted the operator is. Poor explanation, but more or less to the point.

Webers and the like have an accelerator pump system instead, hence ****e fuel economy when you run a 45 DCOE on a mini instead of twin SU's

Now - carb wise

Nova SR pierburg 2e twinchoke & matching manifold VS mk1 Astra 1.6 manifold & GM varajet twinchoke

Which & why?

[meritlover]

Motorcycle CV carbs have a butterfly and a slide, the butterfly opens as a throttle. The slide position depends entirely on engine vaccum thus doing away with any need for an accelerator pump. The carb slide position depends entirely on load, so as such the carb will only ever open up as much as the engine needs nomatter how hamfisted the operator is. Poor explanation, but more or less to the point.

Webers and the like have an accelerator pump system instead, hence ****e fuel economy when you run a 45 DCOE on a mini instead of twin SU's

thank you for restoring my confidence in man kind. A correct answer at last. well written, technically accurate and informative. there was too much false data in the previous posts and a meritlover response woult have resulted in personal attacks, abuse and tears which must always be avoided.

i can tell we are already feeling each other.
xxx

[mowgli]

if you can find a varajet with a 1.3 manifold, you will be very lucky. the performance is better than the pierburg, the economy is about the same, but they are rarer than a bacon sandwich in tel aviv...

i never understood why gm stopped using their own carb & bought in..

[Stuart]

if you can find a varajet with a 1.3 manifold, you will be very lucky. the performance is better than the pierburg, the economy is about the same, but they are rarer than a bacon sandwich in tel aviv...

i never understood why gm stopped using their own carb & bought in..

Costly, and in that era carbs main stream death was on the cards. Just buy in what is mass produced, cheap, reliable enough and isnt going to leave a factory of your own guys out of work when superior injection comes along.

You can still run a slide only carb, it is possible. Ok so I got the SU butterfly bit wrong, meh I can deal with that, I wont cry

[mowgli]

they lasted another 6 odd years, and they were still fitting them to astras at the same time as putting pierburgs on novas...

[Stuart]

6 years is 'only' one maybe two model revisions, while injection planning and testing would have been well under way (took 5 years to upgrade Transit to a proper PCM and that was in the time of really fast development)