Classic Mini HIF Carb questions
Created by: Jreall67
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Last post: Feb 16, 2019 Member since:Jul 3, 2018
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Okay, I figured it out. When I rebuilt the carb, I installed the brass jet bearing upside down. This meant the dashpot piston was too high at rest. Fixed and running good.
Jack
Jack
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As has been said, the HIF contains a bimetallic compensator which leans out the mixture as the engine warms up. The difficulty is that, as you try to adjust the mixture, the car is sitting still with the engine running and the carb gets warmer and warmer - more than it would while underway with air flowing around the motor. So, as you adjust, the compensator is also adjusting. You end up trying to make it richer while the compensator makes it leaner. Then when you go for a drive, the air flows around the motor and the carb returns to a better temperature, with the compensator relaxing and leaving you running rich. (Rolling road tuning shops often use huge fans to simulate road-going air movement which would help.)
No matter what instruments you use with the car stationary and the bonnet up, you'll face this problem. One solution is to road test after adjusting, and using a small amount of choke to see if driveability improves. Re-adjust and re-test until the choke application stops improving driveability.
No matter what instruments you use with the car stationary and the bonnet up, you'll face this problem. One solution is to road test after adjusting, and using a small amount of choke to see if driveability improves. Re-adjust and re-test until the choke application stops improving driveability.
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"Hang on a minute lads....I've got a great idea."
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Would tuning mixture with a vacuum gauge work also?
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No, but I will check on both.
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have you got a tach and colortune? Easiest way to get it right.
Total posts: 14
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Thanks, I will check these out. It is definitely too lean.
Jack
Jack
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Make sure you have oil properly in the dashpot and it moves smoothly up and down..
Make sure you are adjusting the mixture screw the way you want = Richen vs Lean
The HIF is slighty Backwards in the mind to making this adjustment.. you have to keep that in mind.
Screw in = Richens mixture
Screw Out = Leans Mixture.
If you richen the mixture + and it revs up = means the Butterfly / Throttle plate is OPEN and its able to consume the additional fuel its being given.
Pull your dashpot and see where the Jet is sitting in relation to the 'bridge' Turn the mixture screw and watch the jet move in relation.
1/16th is equal to one "flat' on a standard HS Carburator..
Dying at hot sounds like its too lean.. (needs more fuel) as there is a temperature compensator in the carb that will lean as it warms up ...
Make sure you are adjusting the mixture screw the way you want = Richen vs Lean
The HIF is slighty Backwards in the mind to making this adjustment.. you have to keep that in mind.
Screw in = Richens mixture
Screw Out = Leans Mixture.
If you richen the mixture + and it revs up = means the Butterfly / Throttle plate is OPEN and its able to consume the additional fuel its being given.
Pull your dashpot and see where the Jet is sitting in relation to the 'bridge' Turn the mixture screw and watch the jet move in relation.
1/16th is equal to one "flat' on a standard HS Carburator..
Dying at hot sounds like its too lean.. (needs more fuel) as there is a temperature compensator in the carb that will lean as it warms up ...
Total posts: 14
Last post: Feb 16, 2019 Member since:Jul 3, 2018
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Cars in Garage: 0
Photos: 0 WorkBench Posts: 0 |
I have a new to me classic mini. I just rebuilt my HIF44 carb and am trying to adjust. Its getting better, but still not great. High RPM at idle. Dies occasionally at stops after a warm up drive, then takes the choke and some cranking to get it to restart. My most recent adjustment has me at 1 1/2 turns out on the mixture screw. I cannot lower the idle screw any more or it goes from about 12-1300 to dying. The needle was a BAW (jag needle) when I took it apart. It now has a new BBC needle in it. Plugs show too lean (white) after last drive.
Engine is: 1380 A+ with 286 cam. distributor and contacts are good. Vacuum leaks have been resolved. Haven't checked fuel pressure or valve lash (it was set at .017" according to records).
I am open to suggestions.
Thanks
Jack
Engine is: 1380 A+ with 286 cam. distributor and contacts are good. Vacuum leaks have been resolved. Haven't checked fuel pressure or valve lash (it was set at .017" according to records).
I am open to suggestions.
Thanks
Jack