• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Float & needle adjustment on SU HS6 - slightly OT

Share this page

T

tdskip

Yoda
Country flag
Offline
Hi guys - this is my first time rebuild a set of HS6 carbs and I have two questions I could use some help on.

1) I'm wondering what float bowl height adjustment, if any, is correct or necessary.

2) I'm also concerned that the needle assembly is incorrect. The needle that came with the carbs is on the left, and it the "pin" in the bottom of it moves and appears to allow for better articulation of the gas intake. The new Viton needle from APT Fast has a mushroom bottom to it and is fixed, and does not have any articulation.

BUT (and here is the slightly OT bit) these HS6 are going on the Volvo 122s, and the intake is an upward cast. When the float is held at the same angle as when mounted on the car it appears to correctly. So as long as the needle moves freely in the as-mounted angle I should be OK - right?

Any coaching on either #1 or #2 for me?

DSCN3647.jpg
 
You own a 122S? I'm envious. I keep watching for an 1800 (any model 1800) to become available near me. Hen's teeth.

I have used both types of needles in HS2s and HS4s. The one on the left should have a bit of "spring action" with that small button. I have not had problems with either type. With plastic floats you have to set the level using fiber washers while earlier floats allowed you to bend the tabs to get the right level.

Regardless, the HS carb installations I've seen always use mounting blocks for the float bowl to keep the bowl more or less level. The carbs typically aren't installed with the bowl angled off vertical. So that begs the question, did your HS6 originally fit a Volvo manifold or did it come from elsewhere? You can change the bowl mounting block to get it vertical.
 
Hi Doug - thanks for the note.

I have a stock Volvo manifold, and they are tilted upwards. I believe this is correct, and the reference pictures I took on stock cars seems to confirm this. So it sounds like either I'm missing the mounting blocks, which would have an angle in them to offset the lean, or they are supposed to be at an angle.

When I hold the float flat I don't think I'll get enough fuel flow, but at the angle it looks (hardly scientific) OK. I'll call and double check that the needles are cool for how they'll be mounted. I did double check at the time I bought the needles, in person, with APT Fast that they were meant for the Volvo.

Here are the reference pic for what it is worth

122referencepics25.jpg


122referencepics5.jpg


FYI - here she is. Trying to get her back on the road after 5+ years and a fair amount of neglect.

IMG00118-20090204-1543-1.jpg


The rally I posted about had this 122s on it - fast fast fast. Darn thing had no lean in corners.

2009SoCalTT27.jpg


IMG_0668.jpg


Last thing Doug - there were two wicked fast Mini's on the run.

IMG_0628.jpg
 
Do you have any pictures of how the bowls are sitting. It looks like they may be sitting level but can't tell for sure.

I am not sure but isn't the bowls that need to sit flat?
 
Duh - well that seems obvious now. Tom, you are spot on. Between you and Doug it just clicked.

I just did a test fitting and while the carb main body is in fact angled up, the float bowl mounting points are angled in a way where they are in fact flat. I missed that - sorry for the brain fade on my part.

So - back to the float height. Should be fully closed when the float is level with the top of it's travel. Even with the float at a +/- 15 degree angle so it is open there isn't much needle travel. The needle comes down, but only slightly. Is that normal?

DSCN3648.jpg
 
Looks fine to me, Skip.

ISTR you are supposed to check and adjust float height if it's way off; the adjustment is either bending the arm or adding washers under the valve body. But I can't lay my hands on my Haynes at the moment to tell you what the measurement should be.
 
I don't have the SU manual here but for my spit I want to say the float distance it 1\8 inch between the float and the top ring.

Here is a link that may help. This isn't specific for your car but this may help.
https://www.gowerlee.dircon.co.uk/Tips.htm
 
Will will find all kinds of stuff for tuning the SU if you do a google search on setting float level on SU carbs or Turning SU carbs and so on.
 
From that picture I would say it is set to high. Only a guess but float normally angles more to the lid. and would sit at an angle not straight across. But your Volvo manual should tell you the right height.
 
Thanks Tom - I agree and digging into this confirms guys guys are right. When upside down the float should angle down towards the outside of the lid (moving away from the needle).

I think the way they were set when I disassembled them - they were actually point up! - threw me off. My goodness, how the bloody car ran with this things as originally set up is beyond me. Then again, maybe it didn't and that is why it ended up parked.

Thanks guys!
 
That looks better.
 
PERFECT!!!

And if ya need another manifold, I have one here.
 
?? I can't see any pictures? Any Ideas why?

Also since we're in the Triumph forum and I am preparing to put SUs on my TR6... What do you do with all the extra pollution control hoses? Mine is a 1975. It has loads of hoses, carbon canister.... The only things I think it needs are the brake booster line and the vent line from the valve cover.
Should the line from the valve cover go directly to the manifold? Currently it splits and goes into a port on each Stomberg.

Thanks,
Bob

BTW. I still cannot seem to post pictures. If anyone wants to explain the proceedure please do.
 
bobh said:
?? I can't see any pictures? Any Ideas why?

Also since we're in the Triumph forum and I am preparing to put SUs on my TR6... What do you do with all the extra pollution control hoses? Mine is a 1975. It has loads of hoses, carbon canister.... The only things I think it needs are the brake booster line and the vent line from the valve cover.
Should the line from the valve cover go directly to the manifold? Currently it splits and goes into a port on each Stomberg.

Thanks,
Bob

BTW. I still cannot seem to post pictures. If anyone wants to explain the proceedure please do.
Click to expand...
No, Bob, don't do that ! The best way to vent your valve cover is by running the hose from the valve cover nipple to the back of your air filter housing. I'd bet that there is a hole in the housing already; you'll just have to rig up a brass or plastic nipple fitting to accept the hose. You can eliminate all the other lines to the Carbon Canister and the one to the diverter/relief valve as well.
You will have a fuel tank vent line to the Carbon Canister that must remain open, however.
I've seen different ways of dealing with that. Some just leave it open to the atmosphere if they remove the CC, some leave it as the sole connection on the CC, and some place a "T" fitting in the Valve Cover hose and connect it there, so that it's vented to the carb's air filter along with the valve cover vapors.
The latter would be the way I'd choose to do it.
 
The pictures are on my computer. I don't have any kind of photo sharing site.

The odd thing is that I can see th pictures in another posting about identifying a TR6 head.

Thanks for the input on the crank case vent. What I plan is to use 3 SUs instead of 3 Strombergs on a Richard Good manifold. I will either run a Good Parts cool air box or individual aftermarket air cleaners. This is a new project so there are numerous things to be done. A friend modified the throttle shafts to avoid interference with the float chamber. Basically he offset a short portion of the shaft to clear the float chamber. It looks like a crank shaft. If the money holds out I also want to modify a head with higher compression, Clean up the ports according to Kastner's suggestions, and install a performance cam. Nothing radical other than the attempt to use 3 SUs.

I hope to post some pictures of the project as it progresses.

Thanks again,
Bob
 
Back
Top