HS2 carburetor question… now with video!

[jehuie]

In the process of rebuilding two of these. One snaps closed quickly as I think it should. The other sinks down more slowly. But is this ok? There is no damper oil yet which should slow both of them down more. All I did was clean them both up with acetone.

 

[DrEntropy]

Check that the needle in the "slower" one isn't rubbing in the jet as it lowers. Sometimes the jet can be a bit off center.

Should both drop with a definite "tunk".... (tech term )

 

[jehuie]

Check that the needle in the "slower" one isn't rubbing in the jet as it lowers. Sometimes the jet can be a bit off center.

Should both drop with a definite "tunk".... (tech term )

Thank you for the fast reply. Unfortunately, it slides down significantly slower that the other even when just sliding it inside the removed damper pot. Or with the needle removed. Not sure why. I think it must have been that way before I disassembled it. Maybe a mismatched dashpot?

 

[DrEntropy]

Maybe a mismatched dashpot?

Quite possible. No knowing how many hands have been into the car in its lifetime. Try swapping the tops? That could have happened at some point. Not all folks know (knew) they were somewhat matched to the pistons.

Still consider the jet centering in the "slow" one as well.

 

[jehuie]

Quite possible. No knowing how many hands have been into the car in its lifetime. Try swapping the tops? That could have happened at some point. Not all folks know (knew) they were somewhat matched to the pistons.

Still consider the jet centering in the "slow" one as well.

What is the technique to be sure it perfectly centered?

 

[jehuie]

Also, I saw a rebuild of a slightly different model that had tiny springs on the jets. This one did not and neither did the kit. Is it supposed to? And how far into the hole should they be when I screw them in? I put them all the way down.

 

[DrEntropy]

They (neeldles) should be in the pistons with the shoulder flush at the surface of the piston. Almost hate to suggest it, but there's a tool that substitutes for the needle to center the jets. A kit I've not been able to find on the 'net now.

Stand by, I'll hunt further.

 

[DrEntropy]

The simplest tool but you may have to hunt for it: > 386-300 / GAC6101X SUrvice Tool Kit for SU Tri Carburetors <

"Old school" but works just fine!

 

[DrEntropy]

Also, I saw a rebuild of a slightly different model that had tiny springs on the jets. This one did not and neither did the kit. Is it supposed to? And how far into the hole should they be when I screw them in? I put them all the way down.

Springs are in the "emissions compliant" SU's. Yours are pre-emission. No springs.

 

[jehuie]

They (neeldles) should be in the pistons with the shoulder flush at the surface of the piston. Almost hate to suggest it, but there's a tool that substitutes for the needle to center the jets. A kit I've not been able to find on the 'net now.

That is how I put the first one in. But when I disassembled the 2nd one it was recessed all the way down so I figured that must be right and changed the other to match. Glad I asked. Even more glad you told me!

 

[DrEntropy]

That link I posted has a really comprehensive explanation for setting up the carbs.

 

[jehuie]

Got it to go clunk! Thanks for the help. It is still slower to talk than the other one. But that happens even with the needle fully removed.

 

[XJtom]

Got it to go clunk! Thanks for the help. It is still slower to talk than the other one. But that happens even with the needle fully removed.

do you have digital verniers, looking at your video the slower piston looks like it has minimal air gap to the other, perhaps just measure the piston and compare diameters, the larger size will drop slower, want to make it drop faster? just use W&D paper fine and hand sand it.

 

[BobHaskell]

do you have digital verniers, looking at your video the slower piston looks like it has minimal air gap to the other, perhaps just measure the piston and compare diameters, the larger size will drop slower, want to make it drop faster? just use W&D paper fine and hand sand it.

With the transfer holes taped closed, the piston should take 3 - 5 seconds to drop. See Burlen's web page on rebuilding carbs.

 

[jehuie]

Thank you again everyone. I was able to get both carbs to close properly with some adjusting and things look good on them.

But now onto the next issue!

When I run the car, the back carb has a lot of flow. I can put my hand up to it and feel strong suction. But the front carb has very little flow whether it's idling or running faster. I checked and the butterfly valves on both are operating together correctly. If I take the carbs off the car and turn it over, there seems to be good suction on both sides. But when the carbs are in place it is still extremely lopsided.

Have I done something wrong or is it just a matter of adjusting them now?

 

[XJtom]

Thank you again everyone. I was able to get both carbs to close properly with some adjusting and things look good on them.

But now onto the next issue!

When I run the car, the back carb has a lot of flow. I can put my hand up to it and feel strong suction. But the front carb has very little flow whether it's idling or running faster. I checked and the butterfly valves on both are operating together correctly. If I take the carbs off the car and turn it over, there seems to be good suction on both sides. But when the carbs are in place it is still extremely lopsided.

Have I done something wrong or is it just a matter of adjusting them now?

what is the reading on a vacuum gauge for each carb, if you don't have the tuning type gauge to fit intake of carb i use a standard vacuum gauge which i attach to the carb in front of the throttle or after it which ever is available.

 

[jehuie]

what is the reading on a vacuum gauge for each carb, if you don't have the tuning type gauge to fit intake of carb i use a standard vacuum gauge which i attach to the carb in front of the throttle or after it which ever is available.

Unfortunately, I have the carbs off still so I can't measure it at the moment. I didn't put them back on yet in case I did something wrong with them and need to fix that before going on. I may just re-install them though and try again.

 

[jehuie]

turned out that I had a vacuum leak along the heat shield. I put some sealant on both sides along with the gasket and things are greatly improved. But I think I still haven’t gotten it quite sealed all the way. What kind of sealant do you recommend in there?

 

[XJtom]

what sealer did you use? not sure if this product is available your way - i use permatex "non hardening" easy way to find the leak is to spray water (mist) on suspect areas, when it changes revs you know you found it.

 

[DrEntropy]

For years we've used Hylomar blue for a sealant, impervious to fuels and remains semi-solid. The water mist is a really reliable way to determine where a vacuum leak is located, too.