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Setting up HD8 carburetors
- Thread starter Ralph F.
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Hi Raplh,
It could be a dozen different problems, from not getting enough fuel (float valve or level) to incorrect jet adjustment, to the air pistons sticking. Go here & see if you can get any ideas. It covers nearly everything.
https://www.hazelden.ca/austinhealey/index.html
D
It could be a dozen different problems, from not getting enough fuel (float valve or level) to incorrect jet adjustment, to the air pistons sticking. Go here & see if you can get any ideas. It covers nearly everything.
https://www.hazelden.ca/austinhealey/index.html
D
AndrewMawson
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[ QUOTE ]
I have had both HD8 carburetors off my '67 BJ8 3000 for rebuilding, and now cannot get the car to run. Can someone point me to a monograph on how to set up the pair of HD8 carbs, starting from a not-running situation ?
[/ QUOTE ]
When I set mine up following the guide in the SU book everything was fine EXCEPT the balancing, and it was an absolute pain having to remove the air filters and listen with a pipe for 'the same hiss' and any alteration would be negated by any small difference in the filter charateristics when replaced. As the height of the dashpot is a measure of the relative balance of the carb I did a bit of head scratching.
My solution was very effective and very simple. Remove the oil damper cap fron each carb, cut two exactly equal (hence weigh the same) bits of 1.6mm brazing wire, crinkle one end so it is a friction fit in the oil damper bore and bend a 90 degree so the two bits of wire point at each other horizontally. Adjust with engine stopped so the pointers exactly face each other. Start the engine, and open the throttle. As the pot rises and falls they should exactly track each other if the balance is correct.
... dead simple and cheap and the filters stay put !
AWEM
I have had both HD8 carburetors off my '67 BJ8 3000 for rebuilding, and now cannot get the car to run. Can someone point me to a monograph on how to set up the pair of HD8 carbs, starting from a not-running situation ?
[/ QUOTE ]
When I set mine up following the guide in the SU book everything was fine EXCEPT the balancing, and it was an absolute pain having to remove the air filters and listen with a pipe for 'the same hiss' and any alteration would be negated by any small difference in the filter charateristics when replaced. As the height of the dashpot is a measure of the relative balance of the carb I did a bit of head scratching.
My solution was very effective and very simple. Remove the oil damper cap fron each carb, cut two exactly equal (hence weigh the same) bits of 1.6mm brazing wire, crinkle one end so it is a friction fit in the oil damper bore and bend a 90 degree so the two bits of wire point at each other horizontally. Adjust with engine stopped so the pointers exactly face each other. Start the engine, and open the throttle. As the pot rises and falls they should exactly track each other if the balance is correct.
... dead simple and cheap and the filters stay put !
AWEM
Hello Ralph,
if I have any S.U. problems the first thing I do is to remove the dashpots and pistons, once done I can see where the jet top(s) is. It should be about 1\8" or fractionally less, now with the ignition on (or crank a car with a mechanical fuel pump) I can check for fuel level which should be visible near the top of the jet. If it overflows the float level is too high or the needle valve is passing. Conversely too low or a fuel supply problem\blockage.
After that I check that the needle is correctly fitted in the piston, (shoulder flush with the bottom) and the piston is free in the dashpot. Reassemble and lift the piston which should then fall with a click. If not, then the jet requires centering.
If that is all pretty much OK, look to your ignition. The car will run with quite coarse settings, which then lets you fine tune afterwards.
Reasonable fuel level, jet down in the holder, needle flushish and piston free and it should run.
Alec
if I have any S.U. problems the first thing I do is to remove the dashpots and pistons, once done I can see where the jet top(s) is. It should be about 1\8" or fractionally less, now with the ignition on (or crank a car with a mechanical fuel pump) I can check for fuel level which should be visible near the top of the jet. If it overflows the float level is too high or the needle valve is passing. Conversely too low or a fuel supply problem\blockage.
After that I check that the needle is correctly fitted in the piston, (shoulder flush with the bottom) and the piston is free in the dashpot. Reassemble and lift the piston which should then fall with a click. If not, then the jet requires centering.
If that is all pretty much OK, look to your ignition. The car will run with quite coarse settings, which then lets you fine tune afterwards.
Reasonable fuel level, jet down in the holder, needle flushish and piston free and it should run.
Alec
tahoe healey
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I've had a set like you discribe for nearly 35 years. It works well and can be used on tricarbs. It came with a centering tool and the metal tube can ge used to adjust the floats. You can also lift the damper piston and visably see how much when it is raised to check the mixture. I paid 12 bucks for it then. I still like the Unison glass tube thing too.