11 replies to this topic

[redfish0]

Hi,

My old carb was knackered on my 998cc mini clubman estate. So, I got a replacement one. I think it is a HS4.
I've got the replacement carb on, everything linked up etc. The car runs but the tick over is rather lumpy but given some throttle it picks up nicely.

Thing is, I have not set it up yet. I went looking for the piston lifting pin as per the haynes manual but its not there! Theres not even a hole there for it so its not a case of it falling off, this carb was built without one.
Help! what do I do?

Thanks in advance.

[Guess-Works.com]

Some have them some do not, it's only used during the tuning process to richen the mixture when idling without changing the jet position.

[redfish0]

Thanks, but how do I set the mixture without the lifting pin?

[Guess-Works.com]

turn the jet screw clockwise on the bottom of the carb.

[redfish0]

Sorry to keep on about this but how do I know if the mixture is right?

Looking at the haynes manual, its easy. Press the piston lifting pin and depending on how the engine responds tells me if its too rich or too lean. But theres no lifting pin to do that.

[dklawson]

The method I was taught to use on carbs that don't have the lifting pin was to reach into the throat of the carb using a thin, flat blade screwdriver and use it to lift the piston. On a Mini this is more difficult since the throat of the carb is hard to see and against/toward the firewall. Practice a little with the engine "off" until you've got a feel for how to use a screwdriver to lift the 1/32" or so that is recommended. Some of the old tuning kits used plastic straws that plugged into the top of the piston when you removed the dashpots. If you have anything like this, you can use it as a visual clue to tell how much you've lifted the piston.

[Guess-Works.com]

HBOL strikes again... If it were that easy then engine tuners would be out of work..

That's ok for getting it roughly right, which you can do with adjusting the Jet aswell... what you realy need is a gas analyser ( expensive ) or a Gunsons Colortune, which are not that expensive and value for money, not only will it enable you to get a decent level of tune at idle, but also at higher RPM's

[redfish0]

Thanks for the speedy replys. :grin:

I'll have a practice on the old carb at lifting the piston and see if I can get it to tick over better. Then get it tuned properly when it goes in for its mot.

Thanks again for the advice.

Whats HBOL?

[redfish0]

I give up with cars

I've just had a tinker to try and get it running better. It was a C**p lumpy tickover wanting to stalling with a slight missfire. I've enriched the mixture but now it ticks over too fast, unevenly, missfires I think (on tick over only) and the idle adjustment wont go any further back.

My brake pedal needs pressing further now too

Not only that but my other car, a honda crx, has new suspension that wont fit on the front and the rear is now bone breakingly hard. Plus its sticking rear calipers and knackered exhaust manifold of which I have a replacement that's missing o2 sensor holes.

[vasi]

Whats HBOL?

Haynes Book of Lies

[Bass Man]

OK, which is better a Gas analyser or a colortune?

How are twin carbs tuned with a gas analyser, I can see how the Colortune would do it. I am in the market for one of these at the moment, I would like to buy the right one, although I don't currently have twin carbs there are future possibilities.

[Guess-Works.com]

A gas analyser measures what comes out the back... to tune twins the first thing you need to do is get them balanced, this means air flow must be equal between both carbs, which given that both are of the same condition, same springs needles and jets, that both are then running the same mixtures...

Then you can begin tuning..

This is why most people veer away from twins because they can be a pig to set up, and keep setup.

As for which is better, a gas analyser is more accurate but you need to be able to interpret the results, a colourtune is easier and more of a home tuner item.

The BEST option is to take the vehicle to a reputable rolling road experienced in the particular aspects of the A series and twins who should be able to get the best results from the engine based on you requirements, whether it be torque or economy.