Discussion
I have recently done the final idle tuning to my HP 4150 carb . It is important to get the float levels right first .
1. Car outside with cold engine .
2. Level surface .
3. Plenty of dry towels under the carb .
4. Fire blanket at the ready .
5. Adjust the levels with fuel pump on . Just higher than the correct level fuel pours out but you have to go there to adjust it spot on . It's best to have an assistant to turn the pump off if panic sets in . The wife will do but don't tell her it's anything to do with petrol .
Next I adjusted the 4 idle scews an equal amount to get an even idle then drove round the block testing neutral throttle behaveior between 1000 - 2000 rpm . Then I marked the screws , turned them 1/8 turn and went off round the block again etc etc till was as good as could be . Then I set the idle to 1000 rpm then adjusted all over again because altering the idle mixture alters the idle rpm . In the end my diminishing circles were so small it didn't matter .Then I let it idle for 10 minutes and checked all 8 plugs ; all were exactly the same and very slightly sooty . It's a long frustrating job but it's transformed the low speed driving . Also with air con and cooling fans cutting in together the engine does not now stall .
As an aside I've allways accelerated and braked hard [ that's why I bought it ] but after over 600 miles it hasn't used any oil and there is no sign of bore washing or petrol in the oil so I'm thrilled to bits .
Frank
1. Car outside with cold engine .
2. Level surface .
3. Plenty of dry towels under the carb .
4. Fire blanket at the ready .
5. Adjust the levels with fuel pump on . Just higher than the correct level fuel pours out but you have to go there to adjust it spot on . It's best to have an assistant to turn the pump off if panic sets in . The wife will do but don't tell her it's anything to do with petrol .
Next I adjusted the 4 idle scews an equal amount to get an even idle then drove round the block testing neutral throttle behaveior between 1000 - 2000 rpm . Then I marked the screws , turned them 1/8 turn and went off round the block again etc etc till was as good as could be . Then I set the idle to 1000 rpm then adjusted all over again because altering the idle mixture alters the idle rpm . In the end my diminishing circles were so small it didn't matter .Then I let it idle for 10 minutes and checked all 8 plugs ; all were exactly the same and very slightly sooty . It's a long frustrating job but it's transformed the low speed driving . Also with air con and cooling fans cutting in together the engine does not now stall .
As an aside I've allways accelerated and braked hard [ that's why I bought it ] but after over 600 miles it hasn't used any oil and there is no sign of bore washing or petrol in the oil so I'm thrilled to bits .
Frank
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