rebuilt hiF6 carburetors wont run..

ButterFingers

ButterFingers

Active Member
Hi there,
I have just refitted my pair of HIF6 SU carburetors that were rebuilt by Midel in Sydney , Australia.
The car will only start on full choke and dies when it is pushed off.
This makes it impossible to adjust any settings, slow running and fast idle.
It also will not rev and a friend has suggested that it is fuel starvation?
Any ideas on what to do?
There are no local" mechanics" that know about SU's, only fuel injection o_O

Peter
 
they have probably set the floats for level, not the 45 degrees of the rover....I forget if you have the fuel tap or not but make sure it is on reserve and there is at least 2 gallons in the tank
 
The whole point of the HIF carb. is that the jet is centred on the neutral point of the fuel level in the float chamber meaning that it in practise it doesn't matter which angle, (within reason) the carb is at, the jet sees the same fuel level. The old HF carbs had to have the float chambers set level when the carb was tilted and would still change fuel level on inclines . That's why SU's were not used on the Land Rover/ Range Rover products until the HIF came out. Having said that, the adjustment of the jet is very course and only a fraction of a turn on the adjusting screw will make a big difference to the mixture strength.
 
Hi Peter,

Two things that you can do, firstly invert each carburettor, remove the float chamber cover and check that each float is set to 40 thou. Secondly, adjust each jet so that each is flush with the top of the bridge. Then wind each mixture screw in two full turns. If everything else is as it should be, your engine should now start and idle smoothly, assuming the screws for the idle speed are set accordingly.

I am assuming that BBG or BBV needles have been fitted and yellow graded springs?

Ron.
 
def fuel starvation if engine ran before? have we altered anything else ? timing? are we sure we fuel being pumped ? might be worth popping the fuel connection after filter and before carbs..crank into a jar and see if we getting fuel?
assuming thats OK.. most likely scenario is we have either wrong float level and or wrong piston /needlt - bridge position. have we removed needles and refitted? does piston slide easily ? ought to drop onto bridge body with a light clunk with damper removed.
 
SydneyRoverP6B said:
Hi Peter,

Two things that you can do, firstly invert each carburetor, remove the float chamber cover and check that each float is set to 40 thou. Secondly, adjust each jet so that each is flush with the top of the bridge. Then wind each mixture screw in two full turns. If everything else is as it should be, your engine should now start and idle smoothly, assuming the screws for the idle speed are set accordingly.

I am assuming that BBG or BBV needles have been fitted and yellow graded springs?

Ron.
Click to expand...

Yesterday, with the help of a friend, I did the checks, the jets were too high and of course too lean.
Turned the mixture screws clockwise to lower the jets to top of bridge, making it richer, did the 2 turns in and the car started.....wow.
made further adjustments to jets and more richness (small turns to clockwise) and now starting without the choke, ( the car was warm by this time).
Now awaiting a balance device from the USA , the balance on each carb is not right, lot more suction on the left hand side compared to the right.
Not sure how to use and achieve correct balance, anyone know how to do this before making all the other adjustments?

Peter
 
Hi Peter,

I am pleased to hear that my advice proved helpful :)

To achieve the equivalent suction on both carburettors, you adjust the idle speed screws. Start with one carburettor, then proceed to the other. As you continue, you'll likely find that you'll need to go back and forth between both carburettors as you make the adjustments, fine tuning as you go. What you're looking for is the same degree of suction on each of them. It doesn't matter where the needle on the instrument sits, just ensure that they both read the same when you're finished, and that the idle speed is ideally 650rpm, in park, at operating temperature.

You should ideally use an independent dwell tachometer to monitor engine speed, rather than relying on the inbuilt one.

Ron.
 
SydneyRoverP6B said:
Hi Peter,

I am pleased to hear that my advice proved helpful :)

To achieve the equivalent suction on both carburetors, you adjust the idle speed screws. Start with one carburetor, then proceed to the other. As you continue, you'll likely find that you'll need to go back and forth between both carburetors as you make the adjustments, fine tuning as you go. What you're looking for is the same degree of suction on each of them. It doesn't matter where the needle on the instrument sits, just ensure that they both read the same when you're finished, and that the idle speed is ideally 650rpm, in park, at operating temperature.

You should ideally use an independent dwell tachometer to monitor engine speed, rather than relying on the inbuilt one.

Ron.
Click to expand...


I have a tac/dwell meter so that's OK.
If I slacken the nut on the choke assembly spindle, that would isolate both carbies to be independent, then adjusting the idle for suction would be easier? is that the usual way to do it?
Peter
 
ButterFingers said:
I have a tac/dwell meter so that's OK.
If I slacken the nut on the choke assembly spindle, that would isolate both carbies to be independent, then adjusting the idle for suction would be easier? is that the usual way to do it?
Peter
Click to expand...

Yes, you need to do that too.

Ron.
 
SydneyRoverP6B said:
Start with one carburettor, then proceed to the other. As you continue, you'll likely find that you'll need to go back and forth between both carburettors as you make the adjustments, fine tuning as you go. What you're looking for is the same degree of suction on each of them. It doesn't matter where the needle on the instrument sits, just ensure that they both read the same when you're finished, and that the idle speed is ideally 650rpm, in park, at operating temperature.
Click to expand...

The most important thing is to disconnect the throttle link between the carbs before you start, and adjust it to fit back on without altering anything when you put it back on.
 
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