fuel/air flow

[skates]

does any body know the best way to set up my SU carb on my reliant. i.e the mix of fuel and air

[Cabman77]

This may be of help, I haven`t read it all through and it is about twin carb set up but might point you in the right direction.


http://www.classiccarhub.co.uk/articles/guide_to_setting_up_tuning_su_carburettors.html

[one arm bandit]

turn the mixture nut fully closed and mark one flat on the nut so you can identify it then 3 full turns out, start her up and let the thermostat open so its fully warm, then set the idle at 1000rpm or fast idle then turn the nut a flat at a time out untill you get it running at its fastest and smoothest, if you go to far the revs will sound rough so just go back untill you get it again, then set the idle screw when shes good, (mines at 4 full turns from closed but others will differ slightly depending on mods ive a free flow filter modifyed inlett lecky ignition, volcity stack heat wrapped exhaust with boared out std manifold and cherry bomb, and a fully rebuilt engine new pistons)

[digger06]

https://sites.google.com/site/fifersrelianthintsandtips/carb-stuff/carb-maintenance

[morrag]

The way I have always set SU's for a basic set up, is to close the jet holder right up with its bottom nut. Screw down 11/2 turns, start and warm the motor up to op. temperature, you might have to use choke or whatever to get the initial start. Ensure the choke is fully open,set the throttle abutment to a "fast" tick-over, then using the little spring loaded slide lift button, raise the slide a very small amount. If engine speed goes up weaken the mixture a "flat on the jet holder nut,IE. take it up, if the speed of the motor drops, richen the mixture a "flat" until none, or little variation in engine speed occurs when you raise the slide. Some SU's don't have a slide lifting button, if yours is one of those, use a thin bladed screwdriver to lift the slide, from the carb. intake side, the reason for this is that you don't impede air flow.This will give you a reasonable start point for your car burration, and for most purposes will be all you will need. If you are super fussy, find a quiet piece of straightish road, and do a series of "plug chops" to finalise, as you may require a richer or leaner fuel needle/ jet set up. Give it a try, or alternatively, pay for an electronic gizzmo function check!! or whatever Morrag

[one arm bandit]

i havnt got the slide button thing on mine, how much do you need to lift the piston morrag??

[fifer]

Lifting pin info lift at


http://www.gowerlee.dircon.co.uk/Tips.htm


I have found that the SU carb , as fitted to the Reliant 850cc engine , generally is set up correctly between 21 and 24 flats dependent on air filter or lack of one and the condition of the engine .
Therefore that is why I recommend the 18 flats { 3 full turns as each full turn is 6 flats } as a starting point on an unset up carb .
It gives you a base to start from/return to .
 

[morrag]

Terminal type flat bladed screwdriver, and lift the front of the slide around 1or2 mm, just gentle rocking leverage between inlet tract and slide. Remember however to check the general state of repair of your SU, as all too often I have seen peeps trying to set up a carb. with butterfly pivots so worn they are letting by more air than the induction tract. Same for needle/ jet condition, as if heavily worn, and you will never obtain consistency. However, the SU carb. is very "forgiving" and I have seen them soldiering on in a surprisingly reasonable way, when seemingly knackered!!Fifer may well be right for this particular motor, but this method will base set your SU on almost any engine, at least to allow it to run that is,....Morrag