Carb settings

Bougsy

New Member
Hi all, I’ve just done a complete valve train overhaul on my ‘74 ‘S’ fitted with HIF6 carbs (I think) definitely HIF’s. Before the overhaul the engine was running fine but knew the cam was worn. During the overhaul I’ve fitted one of JR Wadhams uprated cams (an extra 25bhp is claimed ) and changed to electronic ignition (Accuspark kit). Now it’s all back and running I’ve got a misfire under acceleration and it feels like a fuel issue. I’ve balanced the carbs with a gauge and so far I’ve richened each carb by about one and a half turns. It has improved things but not cured it. Now, one and a half turns on each carb seems a lot to me. Because of the new cam do I need to look at different carb needles? Any advice welcomed.
 
Hi all, I’ve just done a complete valve train overhaul on my ‘74 ‘S’ fitted with HIF6 carbs (I think) definitely HIF’s. Before the overhaul the engine was running fine but knew the cam was worn. During the overhaul I’ve fitted one of JR Wadhams uprated cams (an extra 25bhp is claimed ) and changed to electronic ignition (Accuspark kit). Now it’s all back and running I’ve got a misfire under acceleration and it feels like a fuel issue. I’ve balanced the carbs with a gauge and so far I’ve richened each carb by about one and a half turns. It has improved things but not cured it. Now, one and a half turns on each carb seems a lot to me. Because of the new cam do I need to look at different carb needles? Any advice welcomed.


You may well need new carb needles. Remember with HIF6 carbs the screw goes the opposite way to every other carb. In enrichens the mixture and out leans the mixture.

Also, check for intake leaks by spraying some carb cleaner around the intake manifold and carbs mounts when idling. If you see a change in idle you have a vacuum leak causing your issue.

Good luck!

Steven
 
Second time around with HIF6s I used the book method - steel rule on edge across the bridge, set the jet level with the bridge, then turn jet screw in 2.5 turns. Further testing and checking with a wide band O2 sensor prompted a further richening of 1/4 turn. No problems at all, satisfactory power and response. ENgine all stock, well worn - suspect 215k kms...or maybe more? Replaced worn rocker shafts and rockers is only serious work.
 
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