• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

SU float level changes

Share this page

Nelson

Nelson

Jedi Warrior
Country flag
Offline
I working at getting my carbs setup and I am troubled with a strange problem. Today I set the float level as suggested by Bill M. and the engine ran. Later I went to start it again and it wouldn't. When I pulled the domes I could see that the fuel level was well below where I had it set just minutes earlier. The float needles and seats are new but I'm wondering if they could be the cause of this. If not, what else should I look for?? I'm using a new Facet fuel pump.
 
Sounds like your float shafts may be making the floats stick- might want to see that the floats are moving freely.
BillM
 
I used a little plastic eye dropper to remove some of the gas from the bowls before I ran the level check. The floats moved very freely when pushed down to extract the gas. I wanted the system to fill to its own level rather than starting with a high level. I did this a couple of times because my first level adjustment had the level barely below the bridge and that was a tad higher than you had said.
 
Barely below is acceptable but not necessarily safe, around 1/8" is about ideal.
It sounds like you have some kind of inconsistency that needs to be corrected but then it sounds like you will be good to go-
Possibly the needle is sticking in the seat?
 
My friend who painted the Sprite said he once had a set of needles that would sometimes dump fuel out the overflow and then not dump anything for a while. He changed to another set and has not had the problem again. There are a couple of places in town that work on Brit cars so I just might see about getting replacements locally. Thanks for your thoughts.
 
Nelson said:
My friend who painted the Sprite said he once had a set of needles that would sometimes dump fuel out the overflow and then not dump anything for a while. He changed to another set and has not had the problem again. There are a couple of places in town that work on Brit cars so I just might see about getting replacements locally. Thanks for your thoughts.
Click to expand...

Needle and seat vlave can sometime be quirking, I seen them on the race cars thats sat for awhile in between runnig do that, I normally tap the float bowl lid with with the pastic handle of the a screwdriver, but this should not be a problem on regualryl driven car. I normally use the viton tipped needle and seat valves, and get them form Joe Curto.

I'm sure this is what Bill told you, but for everyone else text book float height on the SU HS carbs is with the float lid remove and turned upside down there should about 1/8" - 3/16" of gap between the leading edge of the float and the bottom of the float lid. With the early and new Burlen floats with the metal tang, you can carefully bend it to adjsut flaot level, with the all plastic flaots, you shim them under the needle and seat valve with samll shim, I also get those from Joe Curto.
 
I'll check on those viton needles and the seats. I'm not familiar with viton but I'm guessing that it must be some form of plastic. I sure can't figure that it would be anything other than the needle setup causing the inconsistency of the level.
 
Sounds good to me. I ordered a set from Joe and he will mail them today. In the mean time I can start installing the carpets and inside panels.
 
Back
Top