• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

Adivce on how to center jets of SU HD6 carbs

Share this page

F

fishyboy

Jedi Hopeful
Country flag
Offline
Hi All,
I have been a owner of a BT7 for the last 24 years. I am based in the UK and this is my first post.
This weekend I decided to rebuild the twin SU HD6's. The rebuild was fairly straight forward (apart from trying to remove the lower rear manifold bolt on the rear carb - how do you do it?).

I have two questions:-

Firstly, what is the best way to center the jet. I have followed the SU/Haynes manual but perhaps someone out there has a better solution. It seems more difficult than on the HS6's.

Secondly, how does the diaphragm type jet work? I have HS carbs on another car and see how the jet works, but I just cant work out what role the diaphragm plays on the HD6's.

Many thanks

Phil
 
fishyboy said:
Hi All,
I have been a owner of a BT7 for the last 24 years. I am based in the UK and this is my first post.
This weekend I decided to rebuild the twin SU HD6's. The rebuild was fairly straight forward (apart from trying to remove the lower rear manifold bolt on the rear carb - how do you do it?).

I have two questions:-

Firstly, what is the best way to center the jet. I have followed the SU/Haynes manual but perhaps someone out there has a better solution. It seems more difficult than on the HS6's.

Secondly, how does the diaphragm type jet work? I have HS carbs on another car and see how the jet works, but I just cant work out what role the diaphragm plays on the HD6's.

Many thanks

Phil
Click to expand...

The diaphragm separates the fuel circuit on the float-bowl side of the carb from the venturi area; the fuel can only get in through the jet in the middle of the diaphragm.
Moss sells a jet-centering tool: see item 386-500; there's info (possibly a video) describing its use.
 
Hi Steve,
Just looked at the Moss tool, which looks like its for centering on the HS type carbs. Not to sure it would work with the D type, but I shall investigate.
Thanks
Phil
 
fishyboy said:
Hi All,
I have been a owner of a BT7 for the last 24 years. I am based in the UK and this is my first post.
This weekend I decided to rebuild the twin SU HD6's. The rebuild was fairly straight forward (apart from trying to remove the lower rear manifold bolt on the rear carb - how do you do it?).

I have two questions:-

Firstly, what is the best way to center the jet. I have followed the SU/Haynes manual but perhaps someone out there has a better solution. It seems more difficult than on the HS6's.

Secondly, how does the diaphragm type jet work? I have HS carbs on another car and see how the jet works, but I just cant work out what role the diaphragm plays on the HD6's.

Many thanks

Phil
Click to expand...

Q 0: I reach my hand under the front carb and can just reach the back nut (should be a nut on a stud, not a bolt).

Q 1: I believe the centering tool works on all carbs (it substitutes for a needle). At least, it worked on my HD8s.

Q 2: Already answered.
 
Back
Top