HIF6 Carbs Flooding
Posted: Wed May 18, 2022 8:09 pm
Ahoy !
Encountered flooding probs. with pair of HIF6s in old SD1 V8 in a neglected kit car.
Assumed it was needle valves so replaced and adjusted to 2mm above the base of float chamber rather than 1mm below to give wiggle room. (had a bit of experience with another kit car) No flooding. Having solved other ignition problems but still not starting, have returned setting to 1mm below. Flooding returned !
Being that sort of bloke I have calculated the pressure available to locate needle valve against seat. ( Specific gravity of fuel, volume of float, length of float arm, diameter of needle valve, blah, blah ! ) My conclusion is that the available force is only equal to 5psi. So ! Fitted a Malpassi regulator which is screwed right down ? My final conclusion is that the whole system is suspect and bearing in mind that the float 'bottoms' (actually tops) before the spring in the needle valve fully compresses, that the volume of fuel is small compared to the float volume and that the angle of the carbs must work against any accuracy I am, to put it mildly, not impressed ! Anyone care to add anything before I set light to it ?
Encountered flooding probs. with pair of HIF6s in old SD1 V8 in a neglected kit car.
Assumed it was needle valves so replaced and adjusted to 2mm above the base of float chamber rather than 1mm below to give wiggle room. (had a bit of experience with another kit car) No flooding. Having solved other ignition problems but still not starting, have returned setting to 1mm below. Flooding returned !
Being that sort of bloke I have calculated the pressure available to locate needle valve against seat. ( Specific gravity of fuel, volume of float, length of float arm, diameter of needle valve, blah, blah ! ) My conclusion is that the available force is only equal to 5psi. So ! Fitted a Malpassi regulator which is screwed right down ? My final conclusion is that the whole system is suspect and bearing in mind that the float 'bottoms' (actually tops) before the spring in the needle valve fully compresses, that the volume of fuel is small compared to the float volume and that the angle of the carbs must work against any accuracy I am, to put it mildly, not impressed ! Anyone care to add anything before I set light to it ?